Fluid Mechanics Flashcards
The fluid property, due to which, mercury does not wet the glass is
- surface tension
- viscosity
- cohesion
- adhesion
surface tension
Laminar flow of a Newtonion fluid ceases to exist, when the Reynolds number exceeds
- 4000
- 2100
- 1500
- 3000
2100
When the momentum of one fluid is used for moving another fluid, such a device is called a/an
- jet pump
- blower
- acid egg
- none of these
jet pump
The normal stress is the same in all directions at a point in a fluid, when the fluid is
- non-viscous.
- incompressible.
- both (a) and (b).
- having no motion of one fluid layer relative to the other.
having no motion of one fluid layer relative to the other.
Hydraulic mean depth (Dm) for a circular pipe of diameter ‘D’ flowing full is 0.25 D. For a circular channel, at Dm = 0.3 D, gives the condition for the maximum
- flow rate
- mean velocity
- both ‘a’ & ‘b’
- neither ‘a’ nor ‘b’
mean velocity
The head loss in turbulent flow in a pipe varies
- as velocity
- as (velocity)²
- inversely as the square of diameter
- inversely as the velocity
as (velocity)²
Most commonly used joint in the underground pipe lines is the
- sleevejoint
- coupling
- flange
- expansion joint
sleevejoint
Schedule number of a pipe, which is a measure of its wall thickness, is given by
- 1000 P’/S
- 100 P’/S
- 1000 S/P’
- 10000 P’/S
1000 P’/S
The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the
- discharge.
- suction.
- suction minus vapor pressure of the liquid at suction temperature.
- discharge minus vapor pressure of the liquid at the discharge temperature.
suction minus vapor pressure of the liquid at suction temperature.
With increasing flow rate, the hydraulic efficiency of a centrifugal pump
- monotonically decreases.
- decreases and then increases.
- remains constant.
- increases and then decreases.
monotonically decreases.
The velocity profile for turbulent flow through a closed conduit is
- logarithmic
- parabolic
- hyperbolic
- linear
logarithmic
In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of
- relative roughness.
- absolute roughness.
- friction co-efficient for flows at equal Reynold number.
- all (a), (b) & (c).
friction co-efficient for flows at equal Reynold number.
Water hammer in a pipeline results from the
- bursting of pipelines due to closure by a valve.
- rapid pressure change due to a rapid change in the rate of flow.
- pressure increase due to closure of a valve resulting in decrease in rate of flow.
- none of these.
rapid pressure change due to a rapid change in the rate of flow.
Molten soap mass is transported by a __________ pump.
- diaphragm
- reciprocating
- gear
- centrifugal
centrifugal
Which of the following denotes the effect of compressibility in fluid flow ?
- Weber number
- Mach number
- Euler number
- Reynolds number
Mach number
Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe.
- smaller than
- larger than
- same as
- twice
smaller than
The terminal velocity of a small sphere settling in a viscous fluid varies as the
- first power of its dimeter.
- inverse of the fluid viscosity.
- inverse square of the diameter.
- square of the difference in specific weights of solid & fluid.
inverse of the fluid viscosity.
If the discharge of a centrifugal pump is throttled, then its suction lift
- increases
- decreases
- remains unchanged
- data insufficient to predict
increases
Foot valves provided in pumps are __________ valves.
- relief
- three/four way
- pressure reducing
- directional control
directional control
At high Reynolds number
- inertial forces control and viscous forces are unimportant.
- viscous forces predominate.
- inertial forces are unimportant and viscous forces control.
- none of these.
inertial forces control and viscous forces are unimportant.
Power loss in an orificemeter is __________ that in a venturimeter.
- less than
- same as
- more than
- data insufficient, cannot be predicted
more than
The terminal velocity of a particle moving through a fluid varies as dpn. What is the value of n’ for Newton’s law regime ?
- 0.5
- 1
- 1.5
- 3
0.5
What is the normal range of exit cone angle of a venturimeter ?
- 2 to 5
- 7 to 15
- 15 to 25
- > 25
7 to 15
The dimension of dynamic viscosity is
- ML⁻¹T⁻¹
- L²T⁻¹
- LT⁻²
- ML⁻¹T⁻²
ML⁻¹T⁻¹
A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke’s law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity
- same as that of A.
- one fourth as that of A.
- twice as that of A.
- four times as that of A.
one fourth as that of A.
true ans: four times as that of A.
The pitot static tube does not measure the __________ pressure.
- static
- total
- difference in static & dynamic
- all (a), (b) and (c)
all (a), (b) and (c)
The fluid in which the shearing stress within it is proportional to the velocity gradient across the sheared section, is called a __________ fluid.
- Bingham
- Newtonion
- perfect
- none of these
Newtonion
In fluid flow, cavitation is caused, if the
- fluid velocity decreases to zero.
- total energy decreases.
- both (a) and (b).
- flow pressure approaches its vapor pressure at the prevailing temperature.
flow pressure approaches its vapor pressure at the prevailing temperature.
The ratio of the depth of flow to the hydraulic radius for the most economical trapezoidal section, in open channel flow is
- 0.5
- 1
- 1.5
- 2
2
The drag co-efficient for a bacterium moving in water at 1 mm/s, will be of the following order of magnitude (assume size of the bacterium to be 1 micron and kinematic viscosity of water to be 10⁻⁶m²/s).
- 24000
- 24
- 0.24
- 0.44
0.44
true ans: 24000
For Laminar flow through a packed bed, the pressure drop is proportional to (Vs is the superficial liquid velocity and Dp is the particle diameter)
- Vₛ/Dp²
- Vₛ²/Dp²
- Vₛ²/Dp³
- Vₛ/Dp³
Vₛ/Dp²
The maximum delivery pressure of compressors can be upto __________ atmospheres.
- 10
- 100
- 250
- 1000
1000
Dimension of surface tension is(where, F = force, L = length)
- F · L⁻¹
- F⁻¹ · L
- F · L⁻²
- F⁻² · L
FL⁻¹
Which of the following is not a dimensionless parameter ?
- Euler number
- Specific gravity
- Fanning friction factor
- None of these
None of these
Co-efficient of velocity is __________ the coefficient of discharge.
- less than
- more than
- equal to
- not related to
more than
All pipes of a particular nominal size have the same
- inside diameter
- outside diameter
- thickness
- none of these
outside diameter
For the transfer of solution of thick slurry, the pump used is a __________ pump.
- reciprocating
- gear
- diaphragm
- centrifugal
diaphragm
Which of the following is not concerned with the fluid-particle interaction ?
- Drag co-efficient
- Froude number
- Galileo number
- Weber number
Weber number
Maximum theoretical suction lift for water at 15°C by a centrifugal pump is 34 ft. The same for water at 90°C will be __________ ft.
- 40
- 34
- 8
- 37
8
Pressure drag does not depend upon the
- roughness of surface of the body.
- pressure of main flow only.
- length of the body in flow direction.
- all (a), (b) and (c)
all (a), (b) and (c)
Dimension of absolute viscosity is
- ML⁻¹T⁻¹
- MLT⁻¹
- ML⁻¹T
- MLT
ML⁻¹T⁻¹
__________ pumps are axial flow pumps.
- Turbine
- Propeller
- Diffuser
- none of these
Propeller
Brownian movement is prominent in the particle size range of __________ microns in case of settling of a particle in a fluid.
- 2 to 3
- 0.01 to 0.10
- 200 to 300
- 100 to 1000
2 to 3
For a particle settling in water at its terminal settling velocity, which of the following is true ?
- Buoyancy = weight + drag
- Weight = buoyancy + drag
- Drag = buoyancy + weight
- Drag = weight
Weight = buoyancy + drag
A Bingham fluid of viscosity μ = 10 Pa.s and yield stress, τ₀ = 10 KPa, is shared between flat parallel plates separated by a distance of 10⁻³ m. The top plate is moving with a velocity of 1 m/s. The shear stress on the plate is
- 10 KPa
- 20 KPa
- 30 KPa
- 40 KPa
20 KPa
Pick out the correct statement.
- A forced vortex occurs when fluid rotates as a solid about an axis.
- In laminar flow, Newton’s law of viscosity does not apply.
- A free vortex occurs, when fluidrotates as a solid.
- In turbulent flow, there are neither cross-currents nor eddies.
A forced vortex occurs when fluid rotates as a solid about an axis.
Shear stress in a fluid flowing in a round pipe
- varies parabolically across the cross-section.
- remains constant over the cross-section.
- is zero at the centre and varies linearly with the radius.
- is zero at the wall and increases linearly to the centre.
is zero at the centre and varies linearly with the radius.
The resistance wire used in a hot wire anemometer for conducting electrical current is made of
- copper
- tungsten
- chromium
- aluminium
tungsten
Two dimensional stream function
- relates velocity and pressure.
- is constant along a stream line.
- is constant along an equipotential surface.
- none of these.
is constant along a stream line.
What causes cavitation in centrifugal pump ?
- High suction pressure
- Low barometric pressure
- Low suction pressure
- High suction velocity
Low suction pressure
Draining of shallow pits or sump is done by a sump pump, which is a __________ pump.
- single stage vertical
- centrifugal
- plunger
- diffuser
single stage vertical
A hydraulic ram acts as a/an __________ pump.
- centrifugal
- reciprocating
- impulse
- parallel cylinder
impulse
The ratio of average fluid velocity to the maximum velocity in case of laminar flow of a Newtonion fluid in a circular pipe is
- 0.5
- 1
- 2
- 0.66
0.5
Choose the correct set of dimensions of viscosity that are equivalent (where, F, M, L, T are dimensions for force, mass, length and time respectively).
- FL⁻²T, ML⁻¹T⁻¹
- FLT, ML⁻¹T⁻¹
- ML⁻¹T⁻³, F⁻¹L²T
- F⁻¹L²T⁻¹, MLT⁻³
FL⁻²T, ML⁻¹T⁻¹
The line of action of the buoyant force passes through the centre of gravity of the
- submerged body.
- displaced volume of the fluid.
- volume of fluid vertically above the body.
- horizontal projection of the body.
displaced volume of the fluid.
Pick out the wrong statement.
- The shear stress at the pipe (dia = D, length = L) wall in case of laminar flow of Newtonion fluids is D/4L · Δp
- In the equation, τ · g꜀ = k · (du/dy)ⁿ the value of ‘n’ for pseudoplastic and dilatant fluids are < 1 and >1 respectively.
- Shear stress for Newtonion fluid is proportional to the rate of shear in the direction perpendicular to motion.
- With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids.
With increase in the Mach number >0.6, the drag co-efficient decreases in case of compressible fluids.
The friction factor for turbulent flow in a hydraulically smooth pipe
- depends only on Reynolds number.
- does not depend on Reynolds number.
- depends on the roughness.
- none of these.
depends only on Reynolds number.
The pressure at a point in a fluid is not the same in all directions, when the fluid is viscous and
- moving
- static
- cold
- hot
moving
What causes convective acceleration in fluid flow ?
- Steep slope in flow
- Unsteady nature of flow
- Non-uniformity of flow
- Turbulence in flow
Non-uniformity of flow
The Stoke’s stream function applies to the
- irrotational flow only.
- ideal/non-viscous fluids only.
- cases of axial symmetry.
- none of these.
cases of axial symmetry.
Slugging in a fluidised bed can be avoided by using
- tall narrow vessel.
- deep bed of solids.
- shallow beds of solids and proper choice of particle size.
- very large particles.
shallow beds of solids and proper choice of particle size.
The ratio of width to depth for the most economical rectangular section in open channel flow is
- 0.5
- 1
- 1.5
- 2
2
The simple pitot tube measures the __________ pressure.
- static
- dynamic
- total
- none of these
total
Capacity of a hydraulic accumulator is defined in terms of maximum
- amount of energy stored.
- flow rate through accumulator.
- rate of falling of ram.
- volume available in the cylinder.
amount of energy stored.
Three piping networks as shown in the figure are placed horizontally. They are made using identical pipe segments and are subjected to the same pressure drop across them. Assuming no pressure losses at junctions, the flow rates across the three networks are related as Q1 : Q2 : Q3.
- 1:√3: 2
- 1:2:3
- 1:2:2
- 1:√2:√2
1:2:2
Boundary layer separation is characterised by one of the conditions given below, where ‘Re’ is the Reynolds number for the flow. Select the appropriate conditions.
- Re «_space;1, accelerating flow
- Re»_space; 1, accelerating flow
- Re «_space;1, decelerating flow
- Re»_space;1, decelerating flow
Re»_space;1, decelerating flow
Manometers measure the __________ pressure.
- vacuum as well as the atmospheric
- difference in
- absolute
- gage
difference in
Which of the following fluid forces are not considered in the Navier-Stoke’s equation?
- Gravity forces
- Viscous forces
- Pressure forces
- Turbulent forces
Turbulent forces
Which of the following may be termed as a variable orifice flowmeter ?
- Rotameter
- Pitot tube
- V-notch
- All (a), (b) and (c)
Rotameter
In turbulent flow, a rough pipe has the same friction factor as a smooth pipe
- in the zone of complete turbulence.
- when the roughness projections are much smaller than the thickness of the laminar film.
- everywhere in the transition zone.
- when the friction factor is independent of the Reynold’s number.
when the roughness projections are much smaller than the thickness of the laminar film.
Air vessel provided in a reciprocating pump
- smoothens the flow by avoiding pulsations.
- increases the volumetric efficiency of the pump.
- saves the pump from the danger of cavitation.
- none of these.
none of these.
true ans: smoothens the flow by avoiding pulsations.
Bernoulli’s equation is dependent on the
- first law of thermodynamics.
- third law of thermodynamics.
- law of conservation of momentum.
- none of these.
none of these.
true ans: first law of thermodynamics.
The capacity of an accumulator is the maximum
- energy which it can store.
- discharge which it can deliver.
- liquid which it can store.
- none of these.
energy which it can store.
With increase in the temperature, viscosity of a liquid
- increases
- decreases
- remains constant
- may increase or decrease; depends on the liquid
decreases
Vena-contracta pressure tapping is at a distance __________ from the position of an orificemeter fitted in a pipe of internal diameter ‘d’
- d
- 0.5 d
- 2d
- 4d
0.5 d
The pump impeller and the turbine runner in a hydraulic torque converter
- have the same diameter.
- have different diameters.
- are directly coupled.
- none of these.
have different diameters.
true ans: have the same diameter.
Reciprocating pumps compared to centrifugal pumps
- deliver liquid at uniform pressure.
- can handle slurries more efficiently.
- are not subject to air binding.
- can be operated with delivery valve closed.
are not subject to air binding.
The fluid property which matters for falling rain drops to acquire spherical shape is its
- pressure
- height of descend
- viscosity
- surface tension
surface tension
The simple pitot tube does not measure the
- static pressure.
- dynamic pressure.
- velocity at the stagnation point.
- all (a), (b) and (c).
all (a), (b) and (c).
Boundary layer separation occurs when the
- pressure reaches a minimum.
- cross-section of the channel is reduced.
- valve is closed in a pipeline.
- velocity of sound is reached.
cross-section of the channel is reduced.
The head loss in turbulent flow in a pipe varies
- directly as the velocity.
- inversely as the square of the velocity.
- approximately as the square of the velocity.
- inversely as the square of the diameter.
approximately as the square of the velocity.
For flow through an orifice from a reservoir, the actual velocity at the vena con-tracta is given by
- √(2gh)
- C · V · √(2gh)
- Cd √(2gh)
- Cc √(2gh)
C · V · √(2gh)
The ratio of the hydraulic radius to the diameter of the channel, for maximum mean velocity of flow in a circular channel, in open channel flow is
- 0.3
- 0.9
- 0.03
- 0.66
0.3
For the free settling of a spherical particle through a fluid, the slope of, CD-log NRe , plot is
- 1
- -1
- 0.5
- -0.5
-1
A centrifugal pump loses prime after starting. The reason of this trouble may be
- incomplete priming.
- too high a suction lift.
- low available NPSH and air leaks in the suction pipe.
- all (a), (b), and (c).
all (a), (b), and (c).
Venturimeter and orificemeter measures the __________ of the fluid.
- pressure
- maximum velocity
- average velocity
- point velocity
average velocity
Surge tanks are provided in high pressure water pipelines to
- store a definte quantity ofwater all the time,
- reduce the water hammer.
- facilitate easy dismantling of pipeline for cleaning and maintenance.
- none of these.
reduce the water hammer.
Working principle of manometer comprises of balancing a coloumn of liquid against the pressure to be measured. Inclined tube manometer is especially used for the measurement of __________ pressure.
- small differential
- atmospheric
- absolute
- gage
small differential
Isotropic turbulence occurs
- where there is no velocity gradient.
- at higher temperatures.
- only in Newtonion fluids.
- none of these.
where there is no velocity gradient.
The co-efficient of drag and lift for an incompressible fluid depends on the
- Reynolds number
- Froude number
- Mach number
- all (a), (b) and (c)
Reynolds number
Euler’s equation of motion states, that at every point, the
- fluid momentum is constant.
- force per unit mass equals acceleration.
- rate of mass outflow is equal to the rate of mass inflow.
- none of these.
force per unit mass equals acceleration.
The Navier-Stokes equation deals with the law of conservation of
- mass
- energy
- both (a) & (b)
- momentum
momentum
Hydraulic intensifier is used for increasing the
- rate of velocity of liquid supply.
- rate of flow through delivery pipeline of a pump.
- intensity of pressure of the liquid.
- momentum rate through delivery pipe.
intensity of pressure of the liquid.
Which of the following is the ‘Blaussius equation’, relating friction factor to the Reynolds number ?
f = 0.079·(NRe)^-0.25
Hydrometer measures the specific gravity of liquids based on the principles of buoyancy. Pycnometer is used to measure the specific gravity of
- powder & grannular solids
- liquids
- low melting point semi-solids
- all ‘a’, ‘b’ & ‘c’
all ‘a’, ‘b’ & ‘c’
Euler’s equation of motion is a statement expressing
- conservation of mass.
- conservation of energy.
- Newton’s first law of motion.
- Newton’s second law of motion.
conservation of mass.
true ans: Newton’s second law of motion.
During ageing of fluid carrying pipes, the
- pipe becomes smoother with use.
- friction factor increases linearly with time.
- absolute roughness decreases with time.
- absolute roughness increases linearly with time.
absolute roughness increases linearly with time.
Pick out the wrong statement.
- The form drag is dependent upon the occurrence of a wake.
- The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance.
- An ideal fluid is the one, which has negligible surface tension and obeys the Newton’s law of viscosity.
- Existence of the boundary layer in fluid flow is because of viscosity of the fluid.
An ideal fluid is the one, which has negligible surface tension and obeys the Newton’s law of viscosity.
Mass velocity is independent of temperature & pressure, when the flow is
- unsteady through unchanged cross-section.
- steady through changing cross-section.
- steady and the cross-section is unchanged.
- unsteady and the cross-section is changed.
steady and the cross-section is unchanged.
Very small pressure difference (< 5 mm water coloumn) can be most conveniently measured by a/an __________ manometer.
- U-tube water.
- U-tube mercury.
- inclined tube mercury.
- inclined tube water.
inclined tube water.
For pipe flows, head is proportional to __________ at constant capacity(where, D = pipe diameter).
- 1/D
- 1/D²
- 1/D⁵
- D²
1/D⁵
For a given Reynold number as d/D for an orifice increases, Cd will (where, d & D are orifice & pipe diameters respectively).
- increase
- decrease
- remain constant
- either (a) or (b); depends on other factors
increase
The energy equation, E + (P/ρ) + (v²/2g) + gZ = constant (E = internal energy/mass), is applicable to
- perfect gases only.
- isothermal flow of gases.
- adiabatic unsteady flow of gases.
- all compressible fluids.
all compressible fluids.
What is the ratio of fluid carrying capacity of two pipes having diameters d1 and d2 respectively ?
- (d1/d2) ^0.8
- (d1/d2)^0.5
- (d1/d2)
- (d1/d2)^2
(d1/d2)^0.5
true ans: (d1/d2)^2
A differential pressure cell is used for
- measuring small pressure difference in gases.
- measuring small pressure difference in liquids.
- remote recording of pressure difference.
- measuring the difference of the impact & the static pressure.
remote recording of pressure difference.
If more than two branches of pipes are to be connected at the same point, then use a/an
- elbow
- union
- tee
- none of these.
tee
In case of a centrifugal pump, the ratio of total delivered pressure to pressure developed with the impeller is called the __________ efficiency.
- manometric
- mechanical
- volumetric
- overall
manometric
Acceleration head in a reciprocating pump
- increases the work done during delivery stroke.
- decreases the work done during suction stroke.
- does not change the work requirement of the pump.
- increases the work done during suction stroke.
does not change the work requirement of the pump.
The ratio of inertial forces to elastic forces is called the __________ number.
- Reynolds
- Mach
- Euler
- Weber
Mach
The equivalent diameter for flow through a rectangular duct of width B and height H is
2HB/(H+B)
Fluid flow at increasing rate through a diverging pipe is an example of __________ flow.
- steady uniform
- non-steady uniform
- steady non-uniform
- non-steady non-uniform
non-steady non-uniform
The temperature in isentropic flow
- does not depend on Mach number.
- depends on Mach number only.
- cannot drop and then increase again downstream.
- none of these.
depends on Mach number only.
A fluid element has a velocity V = -y^2 . xi + 2yx^2 . j. The motion at (x, y) = (l/√2, 1) is
- rotational and incompressible
- rotational and compressible
- irrotational and compressible
- irrotational and incompressible
rotational and compressible
Check in a centrifugal pump is
- provided in the discharge line.
- generally a globe valve.
- provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running.
- all (a), (b) and (c).
all (a), (b) and (c).
Drag force acting on a body does not depend upon the
- density of the fluid.
- density of the body.
- velocity of the body.
- projected area of the body.
density of the body.
Centrifugal pump is normally classified on the basis of the
- rpm.
- type of casing.
- impeller blade angle.
- number of blades in impeller.
type of casing.
Where does the maximum stress occur in case of laminar flow of incompressible fluid in a closed conduit of diameter ‘d’?
- At the centre
- At d/4 from the wall
- At the wall
- At d/8 from the wall
At the wall
In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where, T = absolute temperature )
- 1/√T
- 1/T
- √T
- T
√T
Applying a pressure drop across a capillary results in a volumetric flow rate ‘Q’ under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is
- Q/2
- Q/4
- Q/8
- Q/16
Q/16
Cd, Cc and Cv are related (for flow through an orifice) as (where, Cd = discharge co-efficient;
Cc = co-efficient of contraction
= area of jet at vena-contracta/area of opening
Cv = co-efficient of velocity
=actual velocity at vena-contracta/theoretical velocity)
- Cd = Cc/Cv
- Cd = Cc · Cv
- Cd = Cv/cc
- none of these
Cd = Cc · Cv
In an incompressible fluid, the density is
- greatly affected by moderate changes in pressure.
- greatly affected only by moderate changes in temperature.
- not affected with moderate change in temperature & pressure.
- sensible to changes in both temperature & pressure.
not affected with moderate change in temperature & pressure.
Check valves are used
- at high pressure.
- in bends.
- for controlling water flow.
- for unidirectional flow.
for unidirectional flow.
Velocity distribution for flow between two fixed parallel plates
- varies parabolically across the section.
- is constant over the entire cross-section.
- is zero at the plates and increases linearly to the midplane.
- none of these.
varies parabolically across the section.
Priming is needed in a __________ pump.
- reciprocating
- gear
- centrifugal
- diaphragm
centrifugal
Which of the fluid forces are not considered in the Reynold’s equation of flow ?
- Viscous forces
- Turbulent forces
- Pressure forces
- Compressibility forces
Compressibility forces
For ideally incompressible fluid, the Mach number will be
- 1.5
- 1
- 0
- 5
1
true ans: 0
A mono pump is a __________ pump.
- centrifugal
- piston
- positive acting rotary
- a group of vacuum
positive acting rotary
Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of __________ flow type.
- axial
- radial
- mixed
- none of these
axial
true ans: mixed
The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are
P. Inlet pressure Q. Compressor rpm
R. Delivery pressure S. Volumetric flow rate at inlet.
- P, Q and R
- P and R
- R and S
- P, R and S
P, Q and R
true ans: P, R and S
Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller.
- radius of
- speed of
- fluid velocity leaving
- none of these
none of these
Pick out the Hagen-Poiseulle’s equation.
Δp = 32・μLV/gcD²
In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where M = molecular weight of the gas)
- 1/√M
- √M
- 1/M
- M
1/√M
Boundary layer separation is caused by the
- reduction of pressure to vapour pressure.
- boundary layer thickness reducing to zero.
- adverse pressure gradient.
- reduction of pressure gradient to zero.
adverse pressure gradient.
With increase in temperature, the vapor pressure of liquids
- increases
- increases linearly
- decreases
- remains constant
increases
A mercury (specific gravity = 13.6) manometer connected across an orificemeter fitted in a pipe shows a manometer reading of 2 cms. If the manometer liquid is changed to carbon tetrachloride (specific gravity = 1.6), then for the same flow rate of water the new manometer reading will be __________ cms.
17
42
84
1.8
17
The ratio of wall drag to total drag in the Stoke’s law range is
- 0.5
- 1
- 1/3
- 2/3
2/3
Rotary vacuum pumps can reduce the absolute pressure to as low as __________ mm Hg.
- 1
- 0.1
- 0.01
- 0.001
0.01
A pitched-blade turbine draws __________ a straight blade turbine.
- less power than
- more power than
- same power as
- data insufficient to predict
less power than
The most suitable flow measuring device for the fluid flow measurement in a very large diameter pipeline is a
- weir
- pitot tube
- Kennison nozzle
- V-notch
pitot tube
true ans: Kennison nozzle
A centrifugal pump is called a turbine pump, if it is having a
- turbine type impeller.
- vaned diffusion casing.
- rotating vaned volute.
- none of these.
vaned diffusion casing.
Remote control valve is a __________ valve.
- gate
- butterfly
- needle
- globe
butterfly
Which of the following quantities are computed by using the hydraulic radius for non-circular ducts ?
- Velocity and relative roughness.
- Head loss and velocity.
- Reynold number, relative roughness and head loss.
- Reynolds number and friction factor.
Reynold number, relative roughness and head loss.
Centre of pressure in an immersed body is __________ the centre of gravity.
- above
- below
- at
- either above or below; depends on the liquid density
below
The centre of pressure is
- always below the centroid of the area.
- always above the centroid of the area.
- a point on the line of action of the resultant force.
- at the centroid of the submerged area.
a point on the line of action of the resultant force.
Pascal law is not applicable for a/an __________ fluid.
- accelerating frictionless
- static
- uniformly moving
- none of these
none of these
In a fluidised bed reactor
- temperature gradients are very high.
- temperature is more or less uniform.
- hot spots are formed.
- segregation of the solids occurs.
temperature is more or less uniform.
The flow of a liquid through tapering pipe at a constant rate is an example of __________ flow.
- steady uniform
- steady non uniform
- unsteady uniform
- unsteady non uniform
steady non uniform
Pick out the correct statement pertaining to transition/ entrance length in fluid flow.
- The length of entrance region of pipe, in which full development of fluid flow takes place such that velocity profile does not change downstream, is called the transition length.
- Transition length for laminar flow of Newtonion fluids in a pipe of diameter ‘d’ is equal to 0.05. D.NRe.
- Transition length for turbulent flow of Newtonion fluids in a smooth pipe of diameter ‘d’ is equal to 50 D.
- all (a), (b) and (c).
all (a), (b) and (c).
A perfect gas
- does not satisfy PV= nRT.
- is incompressible and has zero viscosity.
- has constant specific heat.
- can’t develop shear stresses.
has constant specific heat.
In a/an __________ , the flow rate of fluids is obtained by measuring the difference between the impact and the static pressure.
- rotameter
- pitot tube
- venturimeter
- flow nozzle
pitot tube
During fluid flow, variation of shear stress(τ) with velocity gradientat constant pressure temperature is shown below in the figure.
In the above figure, Binghom plastic is represented by the curve .
- V
- II
- III
- I
II
Speed of sound in an ideal gas depends on its
- temperature
- pressure
- specific volume
- none of these
temperature
A centrifugal pump designed for handling water (μ = 1 cp) will deliver __________ when pumping a thicker oil (μ = 30 cp).
- less head & capacity
- more head
- more capacity
- less head & more capacity
less head & capacity
If ‘x’ is the depth of flow in an open channel of large width, then the hydraulic radius is equal to
- x
- x/2
- x/3
- 2x/3
x
In fluid flow, the boundary layer separation can not occur
- in case of boundaries experiencing form drag.
- at points of abrupt changes in the flow directions.
- in laminar flow.
- none of these.
none of these.
For a given fluid flow rate, which of the following incurs maximum head loss ?
- Orifice meter
- Venturimeter
- Flow nozzle
- All of them incur the same head loss
Orifice meter
Which of the following assumptions enables the Euler’s equation of motion to be integrated ?
- The fluid is incompressible.
- The fluid is non-viscous.
- The continuity equation is satisfied.
- The flow is rotational and incompressible.
The fluid is incompressible.
true ans: The fluid is non-viscous.
A fluid whose apparent viscosity increases with shear rate is termed as the __________ fluid.
- Newtonion
- viscous
- dilatant
- non-viscous
dilatant
Which of the following is the most common pump for pumping either raw sewage or sludge ?
- Electromagnetic pump
- Centrifugal pump
- Reciprocating pump
- Gear pump
Reciprocating pump
true ans: Centrifugal pump
Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter.
- 5
- 50
- 500
- 1000
50
For turbulent flow of an incompressible fluid through a pipe, the flow rate Q is proportional to (Δ P)n, where ΔP is the pressure drop. The value of exponent ‘n’ is
- 1
- 0
- < 1
- > 1
< 1
Reciprocating pumps are not able to compete with the centrifugal pump for industrial use, mainly because these pumps have
- very low speeds.
- smaller discharge.
- higher capital & maintenance cost.
- high vibrations.
higher capital &maintenance cost.
Which is the correct relationship for a centrifugal pump ? (where, D = Impeller diameter, inches H = Head developed, ft of liquid pumped N = Speed of pump, rpm)
- D = 1840 (H)^0.5/N
- D = 1840 N/(H)^0.5
- H = 1840 (D)^0.5/N
- D = 1840 H/N
D = 1840 (H)^0.5/N
Which of the following pipe bends will incur the largest head loss ?
- U-bend
- 30° bend
- 45° bend
- 90° bend
U-bend
Which is the most efficient and best for measuring very small flow rate of gases ?
- Venturimeter
- Orifice meter
- Rotameter
- Flow nozzle
Rotameter
When the water is warm, the height to which it can be lifted by a pump
- decreases due to reduced viscosity.
- decreases due to reduced vapour pressure.
- increases due to increased vapour pressure
- decreases due to increased frictional resistance.
decreases due to reduced vapour pressure.
true ans: increases due to increased vapour pressure
Pipes having diameter 14 inches or more are designated by their
- outside diameter
- inside diameter
- schedule number
- none of these
outside diameter
Viscosity of water at 40°C lies in the range of
- 1 x 10⁻³ to 2 x 10⁻³ kg/m.s
- 0.5 x 10⁻³ to 1 x 10⁻³ kg/m.s
- 1 to 2 kg/m.s
- 0.5 to 1 kg/m.s
0.5 x 10⁻³ to 1 x 10⁻³ kg/m.s
A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, the new discharge will be __________ litres/minute.
- 500
- 200
- 1000
- 750
500
The dimension of kinematic viscosity is
- ML⁻²T⁻¹
- L²T⁻¹
- ML⁻²T⁻²
- none of these
L²T⁻¹
A pipe of I.D. 4 m is bifurcated into two pipes of I.D. 2 m each. If the average velocity of water flowing through the main pipe is 5 m/sec, the average velocity through the bifurcated pipes is
- 20 m/sec
- 10 m/sec
- 5√2 m/sec
- 5 m/sec
10 m/sec
Turbulent flow generally occurs for cases involving
- highly viscous fluid
- very narrow passages
- very slow motion
- none of these
none of these
Lower BWG means __________ of the tube.
- lower thickness
- lower cross-section
- outer diameter
- inner diameter
lower cross-section
For laminar flow of Newtonion fluid in a circular pipe, the velocity distribution is a function of the distance ‘d’ measured from the centre line of the pipe, and it follows a __________ relationship.
- logarithmic
- parabolic
- hyperbolic
- linear
parabolic
The Prandtl mixing length is
- zero at the pipe wall and is a universal constant.
- independent of radial distance from the pipe axis.
- independent of the shear stress.
- useful for computing laminar flow problems.
useful for computing laminar flow problems.
true ans: zero at the pipe wall and is a universal constant
NRe²/NFr is called the __________ number.
- Brinkman
- Galileo
- Archimedes
- Euler
Galileo
The location of centre of pressure, which defines the point of application of the total pressure force on the surface, can be calculated by applying the principle of moments according to which “sum of the moment of the resultant force about an axis is equal to the sum of the components about the same axis”. The centre of pressure of a rectangular surface (of width ‘w’) immersed vertically in a static mass of fluid is at a depth of(where, y = depth of the liquid)
- 1/(y/3)
- 2y/3
- 1/(y/4)
- 3y/4
2y/3
true ans: 3y/4
As the velocity V and thus the Reynolds number of a flow past a sphere increases from very low value, the drag force for Re «_space;1
- increases linearly with V.
- decreases linearly with V.
- decreases as V².
- none of these.
increases linearly with V.
Self-priming centrifugal pump can be used for
- booster service.
- pumping liquid fertilisers (e.g. liquid NH3).
- pumping industrial wastes.
- all (a), (b) and (c).
all (a), (b) and (c).
Water hammer is caused, when water flowing in a pipe is suddenly brought to rest by closing the valve. The extent of pressure thus produced due to water hammer depends on the
- pipe length
- fluid velocity in the pipe
- time taken to close the valve
- all (a), (b) and (c)
all (a), (b) and (c)
Bernoull’s equation does not apply to the functioning of a/an
- venturimeter
- orificem
- pitot tube
- none of these
none of these
What is the shear rate at the pipe wall, in case of laminar flow of Newtonion fluids in a pipe of diameter ‘D’ & length ‘L’ incurring a pressure drop ‘Δp’ with average velocity ‘Vavg’?
- D Δp/8L
- D Δp/4L
- 8・Vavg/D
- 4・Vavg/D
8・Vavg/D
true ans: 4・Vavg/D
Pascal’s law is valid, only when the fluid is
- frictionless and at rest.
- at rest.
- at rest and when the frictionless fluid is in motion.
- none of these.
at rest.
A centrifugal pump is used to pump water through a horizontal distance of 150 m, and then raised to an overhead tank 10 m above. The pipe is smooth with an I.D of 50 mm. What head (m of water) must the pump generate at its exit (E) to deliver water at a flow rate of 0.001 m3/s? The Fanning friction factor, f is 0.0062.
- 10 m
- 11 m
- 12 m
- 20 m
11 m
The pressure head of a flow meter remains constant for
- venturimeter
- orificemeter
- rotameter
- pitot tube
rotameter
A venturimeter can not be used for the direct measurement of
- datum difference in the stretch of pipeflow
- pressure difference in the flow throughpipeline.
- friction loss in pipe flow.
- all (a), (b) and (c).
all (a), (b) and (c).
A double acting reciprocating pump compared to a single acting pump (of almost same size working under same pressure levels) would give almost double
- head
- discharge
- efficiency
- none of these
discharge
Which of the following is used for very accurate measurement of flow of gas at low velocity ?
- Pitot tube
- Rotameter
- Segmental orificemeter
- Hot wire annemometer
Hot wire annemometer
In Newton’s law range, the drag co-efficient for the motion of spherical particle in a stationary fluid is
- 0.44
- 0.044
- 4.4
- 44
0.44
A pressure of 10 m head of water is equivalent to __________ kN/m^2.
- 98
- 147
- 196
- 49
98
A pressure head of 320 metres of water in meters of CCl4 (sp.gr = 1.6) will be
- 100
- 200
- 320
- 160
200
Pick out the Kozney-Karman equation (valid for low NRe) for fluid flow through a packed bed of solids.
[Δp・gc・Dₚ²・ε³ ] / [L・v₀・μ(1-ε)²] = 150
The ratio of the wall drag to the form drag in the Stoke’s law range (for motion of spherical particles in a stationary fluid) is
- 0.5
- 1
- 2
- 0.33
2
For turbulent flow in smooth circular pipe, the velocity distribution is a function of the distance ‘d’ measured from the wall of the pipe and the friction velocity ‘v’, and it follows a __________ relationship.
- logarithmic
- linear
- hyperbolic
- parabolic
logarithmic
Maintenance cost of a __________ pump for a particular duty is the least.
- centrifugal
- reciprocating
- volute
- gear
centrifugal
Choking in case of pipe flow means that a
- specified mass flow rate can not be achieved.
- valve is closed in the line.
- restriction in flow cross-section area occurs.
- none of these.
specified mass flow rate can not be achieved.
Velocity of liquid hydrocarbon fuels in a pipeline can not be measured by magnetic flowmeters, because their __________ is very low/small.
- thermal conductivity
- electrical conductivity
- specific gravity
- electrical resistivity
electrical conductivity
The nominal size of a hose pipe is specified by its
- I.D.
- O.D.
- thickness
- none of these
I.D.
Transition from laminar flow to turbulent flow is aided by the
- surface roughness and curvature (i.e.sharp corners).
- vibration.
- pressure gradient and the compressibility of the flowing medium.
- all (a), (b) & (c).
all (a), (b) & (c).
For flow of fluids through packed bed, the superficial velocity is
- less than the average velocity through channels.
- more than the average velocity through channels.
- dependent on the pressure drop across the bed.
- same as the average velocity through channels.
less than the average velocity through channels.
Cd is always __________ Cc.
- greater than
- less than
- equal to
- either more or less than
greater than
true ans: less than
Buoyant force
- for non-symmetrical bodies is not vertical.
- depends on the depth of the submergence of the floating body.
- depends on the weight of the floating body.
- none of these.
depends on the weight of the floating body.
Which of the following is an undesirable property of a manometric liquid ?
- Non-sticky & non-corrosive nature.
- High vapour pressure.
- Low viscosity & surface tension.
- Low co-efficient of thermal expansion.
High vapour pressure.
Characteristic curves for a centrifugal pump plotted against its capacity is shown in the diagram. x, y and z denote respectively
- efficiency, head and B.H.P.
- head, efficiency and B.H.P.
- B.H.P., efficiency and head
- efficiency, B.H.P. and head
head, efficiency and B.H.P.
Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head.
- manometric
- total
- static
- friction
manometric
The speed of sound in an ideal gas varies as the
- temperature
- pressure
- density
- none of these
temperature
The maximum head that can be developed by a single impeller is __________ ft.
- 25
- 100
- 250-300
- 1000
250-300
The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is
- < 1
- 1
- > 1
- 2
- < 1
The general relationship between speed N, head H, power P and discharge Q for a centrifugal pump is
Q∝N : H∝N² : P∝N³
Q∝N² : H∝N³ : P∝N
Q∝N : H∝N³ : P∝N²
Q∝N³ : H∝N : P∝N²
Q∝N : H∝N² : P∝N³
What is the ratio of the velocity at the axis of the pipe to the mean velocity of flow in case of pipe flow under viscous condition ?
- 0.5
- 0.67
- 1
- 2
2
Foot valve provided in the pump is a __________ valve.
- direction control
- back pressure
- relief
- pressure reduction
back pressure
The discharge co-efficient for an orificemeter does not depend upon the
- pipe length.
- ratio of pipe diameter to orifice diameter.
- type of orifice & the Reynolds number.
- pipe diameter.
pipe length.
Which of the following options will facilitate the achievement of a very high head (say 30 metres) in case of a centrifugal pump?
- Increasing the impeller speed and the volute area.
- Increasing the number of vanes in the impeller.
- Mounting of two or more impellers in series on a single shaft.
- Either of (a), (b) or (c).
Mounting of two or more impellers in series on a single shaft.
An equipotential line is __________ to the velocity vector at every point.
- normal
- abnormal
- tangential
- none of these
normal
Specific speed for a centrifugal pump is
- N√Q / (H)^3/4
- N√Q / (H)^2/3
- N³D⁵ / (H)^1/3
- N√Q/H
N√Q / (H)^3/4
Path followed by water jet issuing from the bottom of a water tank will be a
- parabola (vertex being at the opening).
- hyperbola.
- horizontal straight line.
- zig-zag path (which is geometrically undefined).
parabola (vertex being at the opening).
Which of the following produces maximum pressure difference for transportation of gases ?
- Vaccum pumps
- Blowers
- Fans
- Compressors
Compressors
For flow through a venturi at a particular discharge, the correct relationships among velocities at point X, Y and Z would be
- V1 < V2 < V3
- V2 > V1 and V2 > V3
- V1 > V2 > V3
- none of these.
V2 > V1 and V2 > V3
Drag co-efficient in hindered settling is __________ that in free settling.
- less than
- equal to
- not necessarily greater than
- always greater than
always greater than
Efficiency of power transmission (η) through a circular pipe is given by (ht - hf)/ht, which has a maximum value of __________ percent.
- 33:3
- 50
- 66.6
- 88.8
66.6
One dimensional fluid flow implies the
- flow in straight lines only.
- uniform flow.
- steady uniform flow.
- flow in which transverse components are zero.
flow in which transverse components are zero.
__________ forces act on a particle moving through a stationary fluid.
- Gravity
- Drag
- Buoyant
- all (a), (b), & (c)
all (a), (b), & (c)
In frictional fluid flow, the quantity,
(P/ρ)+(v²/2gc)+gz/gc, is
- constant along a streamline.
- not constant along a streamline.
- increased in the direction of flow.
- none of these.
not constant along a streamline.
Hydraulic radius is the ratio of
- wetted perimeter to flow area.
- flow area to wetted perimeter.
- flow area to square of wetted perimeter.
- square root of flow area to wetted perimeter.
flow area to wetted perimeter.
The unit of bulk modulus of elasticity for a liquid in S.I. unit is
- N
- N/m
- N/m²
- N/m³
N/m²
Power requirement of fans having constant wheel diameter varies __________ fan speed.
- as square of
- directly as
- as cube of
- none of these
as cube of
In the low Reynolds number region, the drag force on a sphere is proportional to
- V
- V^2
- V^4
- V^0.5
V
The continuity equation
- is independent of the compressibility of the fluid.
- is dependent upon the viscosity of the fluid.
- represents the conservation of mass.
- none of these.
represents the conservation of mass.
Experimental study of laminar fluid flow through a circular tube was conducted by
- Reynolds
- Hagen and Poiseuille
- Pascal
- Blake-Plummer
Hagen and Poiseuille
The most economical flow control valve for use with large diameter pipes is a
- butterfly valve
- globe valve
- needle valve
- none of these
butterfly valve
Each term in Bernaulli’s equation represents the __________ of the fluid.
- energy per unit mass
- energy per unit weight
- force per unit mass
- none of these
energy per unit weight
Which of the following is a dimensionless parameter ?
- Angular velocity
- Specific weight
- Kinematic viscosity
- None of these
None of these
If the head over the triangular notch is doubled, the discharge will increase by __________ times.
- 2
- 2.828
- 5.657
- 4
5.657
Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1. If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe, will
- increase.
- decrease.
- remain unchanged.
- increase or decrease depending on the pipe material.
increase.
true ans: remain unchanged.
*
What is the force required (in Newtons) to hold a spherical balloon stationary in water at a depth of H from the air-water iterface? The balloon is of radius 0.1 m and is filled with air.
- 4πg/3
- 0.01πgH/4
- 0.01πgH/8
- 0.04πgH/3
4πg/3
For the laminar flow of a fluid in a circular pipe of radius R, the Hagen-Poisseule equation predicts the volumetric flow rate to be proportional to
- R
- R^2
- R^4
- R^0.5
R^4
Interstage coolers are provided in a multistage compressor to
- save power in compressing a given volume to a given pressure.
- cool the delivered air.
- achieve the exact delivery pressure.
- none of these.
save power in compressing a given volume to a given pressure.
Consider a centrifugal pump having a specific impeller diameter, fixed impeller speed pumping a liquid of constant density at a particular discharge capacity. With decrease in the capacity of the pump, the __________ decreases.
- NPSH required.
- BHP required by the pump.
- head of the liquid pumped.
- all (a), (b) and (c).
all (a), (b) and (c).
Reynolds number is the ratio of
- viscous forces to gravity forces.
- inertial forces to viscous forces.
- viscous forces to inertial forces.
- inertial forces to gravity forces.
inertial forces to viscous forces.
For the manometer set up shown in the figure, the pressure difference PA - PB is given by
- (ρH - ρair) gH
- (ρH - ρL) gH
- (ρH - ρL) gH + (ρL - ρair) . g(L - H)
- (ρH - ρL) gL + (ρL - ρair) gH
(ρH - ρair) gH
The discharge through a venturimeter depends upon
- pressure drop only.
- its orientation.
- co-efficient of contraction only.
- none of these.
pressure drop only.
true ans: none of these.
N. second/m² is
- the S.I. unit of dynamic viscosity.
- the S.I. unit of kinematic viscosity.
- equivalent to one poise.
- equivalent to one stoke.
the S.I. unit of dynamic viscosity.
The distance between metacentre and __________ is called metacentric height.
- water surface
- centre of gravity
- centre of buoyancy
- none of these
centre of gravity
Check valve is used for __________ flow.
- very precise control of
- unidirectional
- multidirectional
- none of these
unidirectional
Capacity of a rotary gear pump can be varied by
- changing the speed of rotation.
- bleeding air into suction.
- bypassing liquid from the suction or discharge line.
- all (a), (b) and (c).
all (a), (b) and (c).
For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor.
- brings about no further reduction of
- increases
- decreases
- none of these
brings about no further reduction of
Power number is the ratio of
- drag stress to inertial stress.
- inertial stress to drag stress.
- inertial stress to gravitational stress.
- gravitational stress to drag stress.
drag stress to inertial stress.
The momentum correction factor for the velocity distribution of laminar flow is
- 1.3
- 1.66
- 2.5
- none of these
none of these
For the same flow rate of a fluid, the pressure drop is the least for
- venturimeter
- orificemeter
- flow-nozzle
- Δp is same for all
venturimeter
The valve commonly used in pipes larger than 2” dia is a
- globe valve
- plug-cock
- gate valve
- check valve
gate valve
Foot valves are provided in the suction line of a centrifugal pump to
- avoid priming, every time we start the pump.
- remove the contaminant present in the liquid.
- minimise the fluctuation in discharge.
- control the liquid discharge.
avoid priming, every time we start the pump.
An ideal fluid is
- frictionless & incompressible.
- one, which obeys Newton’s law of viscosity.
- highly viscous.
- none of these.
frictionless & incompressible.
In area meter (e.g., rotameter), with increase in the fluid flow rate, the
- pressure drop increases linearly.
- pressure drop is almost constant.
- area through which fluid flows does not vary.
- none of these.
pressure drop is almost constant.
Drag co-officient CD, in Stoke’s law range is given by
- CD= 16/Re,p
- CD = 24/Re,p
- CD = 18.4/Re,p
- CD = 0.079/(Re)^0.25,p
CD = 24/Re,p
In power law, ζ = A (du/dy)² + B , then the fluid is
- Newtonian
- dilatant
- thixotropic
- rheopectic
Newtonian
true ans: dilatant
The buoyant force acting on a floating body is dependent on the
- viscosity of the liquid.
- weight of the liquid displaced.
- depth of immersion of the body.
- surface tension of the liquid.
weight of the liquid displaced.
A Newtonion fluid is that
- which follows Newton’s law of motion.
- which needs a minimum shear, before it starts deforming.
- for which shear & deformation are related as τ = μ(∂u/∂y)
- none of these.
for which shear & deformation are related as τ = μ(∂u/∂y)
In case of end to end connection of two or more pipes in series, the __________ each pipe.
- same rate of flow passes through
- head loss is same through
- rate of flow in each pipe is proportional to the length of
- total flow rate is the sum of flow rate in
same rate of flow passes through
Which of the following equations applies to the fluid flow through a packed bed for very large Reynolds number ?
- Fanning equation
- Blake-Pllummer equation
- Hagen-Poiseulle equation
- Kozney-Karman equation
Blake-Pllummer equation
The flow of gas along a pipe in the direction of decreasing pressure causes decrease in its
- viscosity
- specific volume
- velocity
- none of these
specific volume
true ans: none of these
Centrifugal pump can’t be used to pump
- molten sodium (used as a coolant in Fast Breeder Reactor).
- moderately viscous vegetable oil used in soap industry.
- thick molten soap at 80°C.
- none of the above.
thick molten soap at 80°C.
A stream line is
- fixed in space in steady flow.
- always the path of particle.
- drawn normal to the velocity vector at every point.
- a line connecting the mid points of flow cross-section.
fixed in space in steady flow.
Quicksand is an example of a __________ fluid.
- bingham plastic
- dilatent
- Newtonion
- pseudoplastic
dilatent
Correction for capillary effect in manometers (used for pressure measurement) need not be applied, if diameter of the manometer tube is __________ mm.
- < 4
- > 4
- > 12.5
- < 10
> 12.5
Differential manometer measures the
- absolute pressure
- gauge pressure
- pressure difference
- pressure gradient
pressure difference
The pressure and power requirement of a gas fan at constant speed & capacity varies __________ the gas density.
- directly as
- inversely as square root of
- inversely as
- as square of
directly as
Boundary layer thickness in laminar flow over a flat plate increases as(where, d = distance from the leading edge.)
- √d
- d^1/3
- d^2
- d^2/3
√d
Gradually varied flow in open channel is a/an __________ flow.
- steady uniform
- steady non-uniform
- unsteady uniform
- unsteady non-uniform
steady non-uniform
The line of action of the buoyant force acts through the
- centroid of the displaced volume of fluid.
- centre of gravity of a submerged body.
- centroid of the volume of any floating body.
- none of these.
centroid of the displaced volume of fluid.
Cavitation in a centrifugal pump can be avoided by keeping the
- inlet pressure high
- outlet pressure low
- inlet pressure low
- outlet pressure high
inlet pressure high
Vane anemometer
- is an area meter.
- is a variable head meter.
- rotates an element at a speed determined by the velocity of the fluid in which the meter is immersed.
- none of these.
rotates an element at a speed determined by the velocity of the fluid in which the meter is immersed.
The peripherial velocity at inlet of a centrifugal pump having inlet diameter of 25 cms and rotating at 950 rpm is __________ m/sec.
- 1.8
- 12.4
- 186.2
- 736.4
12.4
Laminar flow is characterised by the nonexistence of
- pressure fluctuation.
- eddies.
- deviating velocities.
- all (a), (b)&(c).
all (a), (b)&(c).
The length of the tube necessary for the boundary layer to reach the centre of the tube and for fully developed flow to be established is called the __________ length.
- equivalent
- transition
- Prandtl mixing
- none of these
transition
Select the correct practical example of steady non-uniform flow.
- Motion of water around a ship in a lake.
- Motion of river around bridge piers.
- Steadily decreasing flow through a reducing section.
- Steadily increasing flow through a pipe.
Steadily decreasing flow through a reducing section.
Hydraulic diameter for non-circular ducts is equal to __________ times the area of flow divided by the perimeter.
- two
- three
- four
- eight
four
Terminal velocity is
- a constant velocity with no acceleration.
- a fluctuating velocity.
- attained after moving one-half of total distance.
- none of these.
a constant velocity with no acceleration.
Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement.
- f1 = f2
- f1 < f2
- f1 > f2
- data not sufficient to relate f1 & f2
f1 > f2
For an incompressible fluid, the bulk modulus of elasticity is
- 5 kg/m^3
- ∞ N/m^2
- 1 N
- 0 N/m
∞ N/m^2
A fluid is a substance, that
- has to be kept in a closed container.
- is almost incompressible.
- has zero shear stress.
- flows when even a small shear is applied to it.
flows when even a small shear is applied to it.
The pressure intensity is the same in all directions at a point in a fluid
- only when the fluid is frictionless.
- only when the fluid is at rest having zero velocity.
- when there is no motion of one fluid layer relative to an adjacent layer.
- regardless of the motion of one fluid layer relative to an adjacent layer.
when there is no motion of one fluid layer relative to an adjacent layer.
Which of the following must be followed by the flow of a fluid (real or ideal)?
(I) Newton’s law of viscosity.
(II) Newton’s second law of motion.
(III) The continuity equation.
(IV) Velocity of boundary layer must be zero relative to boundary.
(V) Fluid cannot penetrate a boundary.
- I, II, III
- II, III, V
- I, II, V
- II, IV, V
II, III, V
Mach number is defined as the ratio of the local flow velocity to the sonic velocity in the fluid. For what value of Mach number, the gases are considered incompressible ?
- < 0.3
- > 3
- 50
- 1
< 0.3
Boundary layer exists in flow
- of real fluids.
- over flat surfaces only.
- in pipes only.
- of ideal fluids only.
of real fluids.
Rubber latex is an example of __________ fluid.
- dilatent
- Newtonion
- pseudoplastic
- Bingham plastic
pseudoplastic
Velocity head on sudden enlargement in a horizontal pipe is converted into __________ head.
- elevation
- pressure
- both (a) & (b)
- neither (a) nor (b)
pressure
The frictional resistance in laminar flow does not depend on the
- area of surface in contact.
- flow velocity.
- fluid temperature.
- pressure of flow.
area of surface in contact.
true ans: pressure of flow.
A venturimeter measures the
- velocity head
- pressure
- point velocity
- none of these
none of these
Gradually varying fluid flow is an example of __________ flow.
- non-steady uniform
- non-steady non-uniform
- steady uniform
- steady non-uniform
non-steady uniform
Drag is the force component exerted on an immersed object,
- passing the centroid of the body at 60°to the direction of motion.
- the component being parallel to the flow direction.
- the component being normal to the flow direction.
- none of these.
the component being parallel to theflow direction.
To handle smaller quantity of fluid at higher discharge pressure, use a __________ pump.
- reciprocating
- centrifugal
- volute
- rotary vacuum
reciprocating
Cocks are used to control
- water
- any liquid
- solids
- none of these
any liquid
The dimension of surface tension is
- ML⁻²
- MT⁻²
- MLT⁻²
- ML⁻²T
MT⁻²
Pick out the correct statement.
- Fanning friction factor is inversely proportional to Reynolds number always.
- The property of a randomly packed bed (with raschig rings) is given by the ratio of the total volume to the volume of voids in the bed.
- Mach number in an incompressible fluid is always unity.
- Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow.
Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow.
The friction factor is
- always inversely proportional to the Reynolds number.
- not dimensionless.
- not dependent on the roughness of the pipe.
- none of these.
none of these.
Rubber latex is an example of a __________ fluid.
- pseudoplastic
- bingham plastic
- dilatent
- Newtonion
pseudoplastic
Which of the following factors does not contribute to the pressure drop in a pipeline ?
- Velocity of fluid
- Size of pipe
- Length of pipe and number of bends
- None of these
None of these
The phenomenon occuring during pumping of a liquid solution containing dissolved gases, which may come out of the solution giving rise to gas pockets, is termed as
- evaporation
- cavitation
- sublimation
- stripping
cavitation
Working of a __________ pump characterises mixed flow.
- turbine
- piston
- diaphragm
- none of these
turbine
The equivalent diameter for pressure drop calculation for a fluid flowing through a rectangular cross-section channels having sides ‘x’ & ‘y’ is given by
- 2xy / (x+y)
- xy / (x+y)
- (x+y) / 2xy
- (x+y) / xy
2xy / (x+y)
The rate of change of moment of momentum represents the __________ by the fluid.
- torque applied
- force exerted
- work done
- power developed
torque applied
The discharge through a V-notch weir varies as
- H^3/2
- H^1/2
- H^5/2
- H^2/3
H^5/2
Water flow rate in a pipe of 3.5 metres diameter can be most economically and conveniently measured by a/an
- pitot tube
- venturimeter
- orificemeter
- rotameter
pitot tube
The specific speed of a pump is defined as the speed of a unit of such a size, that it
- delivers unit discharge at unit head.
- requires unit power for unit head.
- delivers unit discharge at unit power.
- none of these.
delivers unit discharge at unit head.
In case of venturimeters, friction losses are about __________ percent of maximum velocity head.
- 2
- 8
- 12
- 20
2
With increase in the schedule number of a pipe of a particular nominal size, the
- wall thickness also increases.
- I.D. of the pipe decreases.
- O.D. of the pipe remains constant.
- all (a), (b) and (c)
all (a), (b) and (c)
Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency)
- ηma x ηm x ηv = ηo
- ηm = ηv . ηma
- ηma = ηm x ηv
- ηv = ηm x ηma
ηm = ηv . ηma
true ans: ηma x ηm x ηv = ηo
For water, when the pressure increases, the viscosity
- also increases
- decreases
- remains constant
- first decreases, and then increases
first decreases, and then increases true ans: remains constant
The head loss due to sudden expansion is
- (v₁² - v₂²) / 2gc
- (v₁ - v₂)² / 2gc
- (v₁ - v₂) / 2gc
- (v₁² - v₂²) / gc
(v₁ - v₂)² / 2gc
true ans: (v₁² - v₂²) / 2gc
Location of vena-contracta in an orificemeter does not depend upon the
- type of orifice.
- density, viscosity & compressibility of the fluid.
- ratio of pipe diameter to orifice diameter.
- pipe roughness.
type of orifice.
true ans : pipe roughness.
At low Reynolds number
- viscous forces are unimportant.
- viscous forces control.
- viscous forces control and inertial forces are unimportant.
- gravity forces control.
viscous forces control and inertial forces are unimportant.
For laminar flow through a closed conduit
- Vmax = 2Vₐᵥ
- Vmax = Vₐᵥ
- Vmax = 1.5Vₐᵥ
- Vmax = 0.5Vₐᵥ
Vmax = 2Vₐᵥ
In Newton’s law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass varies as the __________ of its diameter.
- inverse
- square root
- second power
- first power
square root
true ans: second power
Unsteady uniform flow is represented by flow through a/an
- long pipe at constant rate.
- long pipe at decreasing rate.
- expanding tube at increasing rate.
- expanding tube at constant rate.
long pipe at decreasing rate.
If Blausius or Darcey friction factor is ‘f1’ then the Fanning friction factor is equal to
- f₁/4
- 4f₂
- 2f₁
- f₁/2
f₁/4
Pick out the wrong statement pertaining to fluid flow.
- The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
- The Newtonion fluid velocity in a circular pipe flow is maximum at the centre of the pipe.
- Navier-Stokes equation is applicable to the analysis of viscous flows.
- Hagen-Poiseuille equation is applicable to the laminar flow of Newtonion fluids.
The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
A Newtonion liquid (ρ = density, μ = viscosity) is flowing with velocity v in a tube of diameter ‘D’. Let Δp be the pressure drop across the length ‘L’. For a laminar flow, Δp is proportional to
- L ρv²/D
- L μV/D²
- D ρv²/L
- μ V/L
L ρv²/D
true ans: L μV/D²
While starting a centrifugal pump, its delivery valve should be kept
- opened.
- closed.
- either opened or closed ; it does not make any difference.
- either opened or closed; depending on the fluid viscosity.
closed.
For flow past a flat plate, if x is the distance along the plate in the direction of flow, the boundary layer thickness is proportional to
- √x
- 1/√x
- x
- 1/x
√x
Sewage sludge is an example of the __________ fluid.
- Bingham plastic
- Newtonion
- pseudoplastic
- dilatent
Bingham plastic
In case of a rotameter, the density of the float material is __________ that of the liquid it replaces.
- more than
- less than
- equal to
- either (a) or (b)
more than
true ans: less than
The fluid jet discharging from a 2” diameter orifice has a diameter of 1.75” at its vena-contracta. The co-efficient of contraction is
- 1.3
- 0.766
- 0.87
- none of these
0.766
Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation ?
- Decrease in effect
- Increase in thrust
- Develops noise
- Develops high pressure
Develops high pressure
For a specific centrifugal air blower operating at constant speed & capacity, the power requirement and pressure vary
- directly as square of gas density.
- directly as gas density.
- directly as square root of gas density.
- inversely as gas density.
directly as gas density.
Capillary tube method of viscosity measurement is based on the
- Hagen-Poiseulle’s equation
- Stoke’s law
- Navier-stokes equation
- none of these
Hagen-Poiseulle’s equation
It is possible to integrate an automatic flow controller to a
- flow nozzle
- venturimeter
- rotameter
- none of these
rotameter
For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is
- more
- less
- equal
- independent of porosity
less
true ans: more
For a reciprocating pump, the indicator diagram is the graph between the
- discharge and overall efficiency.
- volume swept by piston for one complete revolution and the pressure in the cylinder.
- angle swept by the crank pin at any instant and the discharge.
- none of these.
volume swept by piston for one complete revolution and the pressure in the cylinder.
The most important factor, which determines the maximum height to which water can be lifted by a pump at standard temperature is the
- barometric pressure
- speed of the impeller
- diameter of the impeller
- both (b) and (c)
barometric pressure
The equation relating friction factor to Reynold number, f^-0.5 = 4 logₑ (NRe/√ f)^-0.4, is called the __________ equation.
- Nikuradse
- Von-Karman
- Blausius
- Colebrook
Nikuradse
true ans: Colebrook
Pressure drop for turbulent fluid flow through a circular pipe is given by
- 64/Re
- 32μLV / gcD²
- 4f · (L/D) · (v²/2gc) · ρ
- f · (L/D) · ρ · (v²/2gc)
4f · (L/D) · (v²/2gc) · ρ
true ans: * f · (L/D) · ρ · (v²/2gc)
What is the co-efficient of contraction, if a fluid jet discharging from a 50 mm diameter orifice has a 40 mm diameter at its vena-contracta ?
- 0.64
- 1.65
- 0.32
- 0.94
0.64
A pipe is defined as ‘hydraulically smooth’, if the friction factor
- is not a function of Reynolds number.
- for a given Reynolds number remains constant even on further smoothening of the pipe.
- is zero irrespective of the Reynolds number.
- none of these.
for a given Reynolds number remains constant even on further smoothening of the pipe.
A Pitot tube indicates 5 cm of water (manometer) when it is being used for measuring velocity of air. The velocity of air in m/sec is
- 5
- 14.1
- 56.22
- 28.2
28.2
Delivery of insufficient quantity of liquid by a pump may be caused by
- air leak in the inlet
- low rpm
- too high a lift
- all (a), (b) and (c)
all (a), (b) and (c)
In case of a __________ the energy of flow is considerably decreased downstream of the machine.
- blower
- turbine
- centrifugal pump
- centrifugal fan
turbine
With increase in the shear rate, the apparent viscosity of pseudoplastic fluids
- increases
- decreases
- remains same
- may increase or decrease; depends on the magnitude of shear rate
decreases
Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about
- 0.42
- 0.62
- 0.82
- 0.98
0.62
Purpose of hydraulic accumulator is to
- ensure intermittant supply of hydraulic pressure.
- increase the pressure and store/ accumulate it.
- accumulate pressure to increase force.
- generate high pressure to operate hydraulic machines like cranes, lifts, presses etc
generate high pressure to operate hydraulic machines like cranes, lifts, presses etc
true ans: ensure intermittant supply of hydraulic pressure.
Pick out the wrong statement.
- Surface tension of a liquid is because of the difference in magnitude of adhesive & cohesive forces.
- A hydrometer used for the determination of specific gravities of liquids works on the principle of buoyant forces.
- In case of unsteady fluid flow, the velocity at any given point does not change with time.
- Turbulent fluid flow is characterised by the rapid fluctuation of instantaneous pressure & velocity at a point.
In case of unsteady fluid flow, the velocity at any given point does not change with time.
Purpose of relief valve in a reciprocating pump is to
- protect the pump against developing excessive pressure.
- facilitate unidirectional flow of liquid.
- reduce the discharge pressure.
- control the rate of discharge.
protect the pump against developing excessive pressure.
Select the correct statement.
- The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter.
- A venturimeter with a given gage difference discharges at a greater rate, when the flow is vertically downward through it, than when the flow is vertically upward.
- For a given pressure difference, the discharge of gas is greater through a venturimeter, when compressibility is taken into account, than when it is neglected.
- The overall pressure loss is the same in a given pipe line, whether a venturimeter or a nozzle with the same throat dia is used.
The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter.
true ans: A venturimeter with a given gage difference discharges at a greater rate, when the flow is vertically downward through it, than when the flow is vertically upward.
The Kozney-Carman equation, rewritten in terms of non-dimensional numbers gives (ΔP/pu2 ) proportional to
- (L/Dp) / Re
- Re / (Dp/L)
- (L/Dp) / Re²
- Re² / (Dp/L)
(L/Dp) / Re
In case of turbulent flow of fluid through a circular pipe, the
- mean flow velocity is about 0.5 times the maximum velocity.
- velocity profile becomes flatter and flatter with increasing Reynolds number.
- point of maximum instability exists at a distance of 2r/3 from the pipe wall (r = pipe radius).
- skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.
skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.
For the same terminal conditions and valve size, the pressure drop in a fully opened globe valve as compared to that in a gate valve is
- more
- less
- equal
- either (a) or (b); depends on the viscosity of the fluid
more
Steady fluid flow occurs, when the derivative of flow variables satisfy the following condition.
- ∂/∂s 0
- ∂/∂t = 0
- ∂/∂s = constant
- ∂/∂t = constant
∂/∂t = 0
What is the maximum theoretical suction lift (metres) of a reciprocating pump ?
- 5
- 10
- 50
- 100
10
true ans: 5
The terminal velocity of a particle moving through a fluid varies as dpn. The value of n is equal to __________ in Stoke’s law regime.
- 1
- 0.5
- 2
- 1.5
2
Function of air vessel provided in a reciprocating pump is to
- reduce discharge fluctuation.
- reduce the danger of cavitation.
- avoid the necessity of priming.
- increase the pump efficiency.
reduce discharge fluctuation.
The Prandtl pitot tube measures the
- velocity at a point in the flow.
- pressure at a point.
- average flow velocity.
- pressure difference in pipe flow.
velocity at a point in the flow.
Pressure drop in packed bed for turbulent flow is given by the __________ equation.
- Kozney-Karman
- Blake-Plummer
- Leva’s
- Hagen-Poiseulle’s
Blake-Plummer
true ans: Kozney-Karman
In the complete turbulence zone (in rough pipes), the
- rough and smooth pipes have the same friction factor.
- laminar film covers the roughness projections.
- friction factor depends upon NRe only.
- friction factor is independent of the relative roughness.
friction factor is independent of the relative roughness.
true ans: friction factor depends upon NRe only.
Which of the following has the minimum compressibility ?
- Water at room temperature
- Air at room temperature
- Oxygen at room temperature
- Nitrogen at room temperature
Water at room temperature
In case of centrifugal fan or blower, the gas capacity varies as
- speed
- (speed)²
- (speed)³
- (speed)^0.5
speed
true ans: (speed)³
Pick out the wrong statement.
- A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocity.
- Newton’s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution.
- Laminar flow of viscous liquids is involved in the lubrication of various types of bearings.
- Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes.
Newton’s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution.
Pick out the wrong statement.
- In a static mass of liquid, the pressure at a point is the same for all liquids.
- Pressure decreases exponentially with elevation in an isothermal atmosphere.
- Atmospheric pressure = absolute pressure-gage pressure.
- As per Pascal’s law, the pressure at a point in a static or uniformly moving fluid is equal in all directions.
In a static mass of liquid, the pressure at a point is the same for all liquids.
The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is
- parabolic
- flat
- flat near the wall and parabolic in the middle
- parabolic near the wall and flat in the middle.
parabolic near the wall and flat in the middle.
true ans: flat
Mach number is the ratio of the speed of the
- fluid to that of the light.
- light to that of the fluid.
- fluid to that of the sound.
- sound to that of the fluid.
fluid to that of the sound.
A piezometer opening measures the __________ fluid pressure.
- static
- undisturbed
- total
- dynamic
undisturbed
true ans: static
Drag force on the float of a rotameter is(where Q = flow rate of the )
- ∝Q
- ∝√Q
- ∝Q^2
- constant
constant
true ans: ∝√Q
The unit of dynamic viscosity in SI unit is
- kg/m . sec
- N/m2
- m² /sec.
- m/N. sec.
kg/m . sec
Pressure drop (Δp) for a fluid flowing in turbulent flow through a pipe is a function of velocity (V) as
- V^1.8
- V^-0.2
- V^2.7
- V^2
V^2
Dean number is concerned with the
- fluid-particle interaction.
- fluid flow through helical pipes.
- power consumption in agitated vessels.
- psychrometry.
fluid flow through helical pipes.
The equation given below is called the __________ .
f^-0.5 = 4.07 logₑ (NRe√f)^-0.6
- Colebrook formula
- Von-Karman equation
- Fanning equation
- none of these
Von-Karman equation
true ans: Colebrook formula
Poise is converted into stoke by
- multiplying with density (gm/c.c).
- dividing by density (gm/c.c).
- multiplying with specific gravity.
- dividing by specific gravity.
dividing by density (gm/c.c).
The fluid velocity varies as the square root of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop fo __________ fluid.
- dilatant
- pseudoplastic
- Bingham plastic
- Newtonion
dilatant
true ans: Newtonion
Kinetic energy of fluid per unit weight represented by the velocity head is given by
- 2v² / gc
- v² / 2gc
- ρv² / gc
- ρ.v² / 2gc
v² / 2gc
At a constant speed of the centrifugal pump . it __________ the impeller diameter.
- capacity varies directly with
- head varies as the square of
- horsepower varies as the cube of
- all (a), (b) and (c)
all (a), (b) and (c)
The pressure co-efficient is the ratio of pressure forces to __________ forces.
- viscous
- inertial
- gravity
- surface tension
viscous
true ans: inertial
Pick out the Blake-Plummer equation (valid for large NRe) for fluid flow through beds of solids.
- Δp/ρ = 4f · (L/D)³(v²/2gc)
- fp = {[150(1-ε)] / NRe } +1.75
- [Δp · gc · Dp² · ε³ ] / [L ·v₀ · μ(1-ε)²] = 150
- (-Δp/δL) · (gc/v₀²) · [(Dp · ε³)/(1-ε)] = 1.75
(-Δp/δL) · (gc/v₀²) · [(Dp · ε³)/(1-ε)] = 1.75
true ans: [Δp · gc · Dp² · ε³ ] / [L ·v₀ · μ(1-ε)²] = 150
As per Newton’s law of viscosity, the shear stress for a given rate of angular deformation of fluid is proportional to(where, μ = fluid viscosity)
- 1/μ
- μ
- μ2
- 1/μ2
μ
If two capillary tubes of dia 0.5 mm and 1 mm are dipped in a pot containing mercury, then the rise of mercury is
- same in both the tubes.
- greater in 1 mm dia tube.
- greater in 0.5 mm dia tube.
- zero in both the tubes.
greater in 0.5 mm dia tube.
true ans: zero in both the tubes.
For laminar flow of a shear thinning liquid in a pipe, if the volumetric flow rate is doubled, the pressure gradient will increase by a factor of
- 2
- <2
- > 2
- 1/2
- 2
true ans: >2
Weber number is the ratio of inertial force to __________ force.
- surface tension
- gravity
- viscous
- elastic
surface tension
The curve of metacentre for a floating body __________ the curve of buoyancy.
- is always below
- is the evolute of
- intersects at right angle
- is tangential to
is the evolute of
At what value of crank angle (roughly), no flow of water from or into the air vessel takes place in case of a double acting reciprocating pump ?
- 40° and 140°
- 45° and 60°
- 90° and 80°
- 20° and 120°
40° and 140°
The range of a particular rotameter can be increased by
- use of floats of different densities.
- no means.
- increasing the diameter of the float.
- decreasing the diameter of the float.
use of floats of different densities.
A compressor that takes suction at a pressure below atmospheric and discharge against atmospheric pressure is called a __________ pump.
- sump
- volute
- vacuum
- submerged
vacuum
A bed of spherical particles (specific gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun’s equation for the above fluid-particle system (in SI units) is given below :
Δ P/L = 375 x 10³ VOM + 10.94 x 10⁶ VOM² (SI units)
If water is to be used as the fluidising medium, in actual operation, the above bed has a height = 1 m. What is the porosity of the fluidised bed ?
- 0.2
- 0.5
- 0.7
- 0.8
0.7
Dimension of kinematic viscosity is
- MLT⁻¹
- L² . T⁻¹
- L²T
- L² . T⁻²
L² . T⁻¹
A streamline is a line in flow field,
- that is traced by all the fluid particles passing through a given point.
- along which a fluid particle travels.
- such that at every point on it, the velocity is tangential to it.
- none of these.
such that at every point on it, the velocity is tangential to it.
While starting an axial flow pump, its delivery valve should be kept
- open
- closed
- either open or closed
- none of these
closed
__________ forces do not act in case of fluid flow.
- Elastic
- Tensile
- Vibratory
- Centrifugal
Tensile
Non-colloidal solution is an example of the __________ fluid.
- non-Newtonion
- Newtonion
- dilatent
- pseudoplastic
Newtonion
Boundary layer separation is caused by the
- reduction of pressure below vapour pressure.
- reduction of pressure gradient to zero.
- adverse pressure gradient.
- reduction of boundary layer thickness to zero.
adverse pressure gradient.
Identification of pipelines carrying different liquids and gases is done by the __________ of the pipe.
- diameter
- colour
- altitude
- none of these
colour
Pick out the correct statement.
- Human blood is a Newtonion fluid.
- A Newtonion fluid obeys Newton’s law of cooling.
- For a non-Newtonion fluid, a straight line passes through the origin in a plot between shear stress and shear gradient.
- Thin lubricating oil is an example of a non-Newtonion fluid.
A Newtonion fluid obeys Newton’s law of cooling.
true ans: Human blood is a Newtonian fluid.
What is the unit of kinematic viscosity in SI unit ?
- M²/sec
- N/m² . sec
- Kg . sec/m
- None of these
M²/sec
Hydraulic __________ works on the principle of Pascal’s law of transmission of fluid pressure.
- press
- turbine
- pump
- coupling
press
A 2” gate valve fitted in a pipe is replaced by a similar globe valve. Pressure drop in gate valve was Δp. For the same discharge, the pressure drop across globe valve is
- Δp
- < Δp
- > Δp
- Δp²
- > Δp
The contraction co-efficient for Borda’s mouthpiece (for frictionless fluid) is
- 0.1
- 0.5
- 0.94
- 1
0.5
Purpose of air lift pump is to
- compress air.
- lift compressed air.
- lift water from a well by using compressed air.
- lift air under negative pressure.
lift water from a well by using compressed air.
Pick out the correct statement pertaining to venturimeter.
- A venturimeter with a fixed pressure drop discharges more, when the flow is vertically downward, than when the flow is vertically upward.
- The co-efficient of contraction of a venturimeter is always unity.
- For a fixed pressure drop, the discharge of a gas through a venturimeter is greater, when compressibility is taken into account, than when it is neglected.
- none of these.
none of these.
true ans: For a fixed pressure drop, the discharge of a gas through a venturimeter is greater, when compressibility is taken into account, than when it is neglected.
For very low pressure and high discharge rate, the compressor used is a/an __________ compressor.
- axial
- reciprocating
- rotary
- none of these
rotary
true ans: axial
Pumping of a corrosive liquid is generally preferred to be done by a __________ pump, as it can be made of a variety of materials including plastics.
- piston
- gear
- positive displacement
- sump
gear
true ans: positive displacement
What is the speed of sound (m/sec) in ordinary water ?
- 1500
- 330
- 1000
- 3000
1500
Two piping system are said to be equivalent, when the __________ are same.
- fluid flow rate & friction loss
- length & friction factor
- diameter & friction factor
- length & diameter
fluid flow rate & friction loss
Potential function is applicable only for __________ flow.
- irrotational
- turbulent
- steady
- none of these
irrotational
Which of the following exemplifies a three dimensional fluid flow ?
- Fluid flow at the inlet to a nozzle
- Fluid flow between parallel plates
- Viscous fluid flow between converging plates
- None of these
Fluid flow at the inlet to a nozzle
Volute of a centrifugal pump should be designed in a fashion, such that the
- kinetic head gets converted into static head.
- moving stream gradually reduces velocity.
- mean velocity remains constant.
- none of these.
kinetic head gets converted into static head.
An ideal plastic substance indicates no deformation, when stressed upto yield stress, but behaves like a Newtonion fluid beyond yield stress. Which of the following is an ideal plastic ?
- Sewage sludge
- Rubber latex
- Blood
- Sugar solution
Sewage sludge
Which law is followed by the velocity distribution in the turbulent boundary layer?
- Parabolic law
- Linear law
- Logarithmic law
- None of these
Logarithmic law
The losses in open channel flow generally vary as the
- inverse of the roughness.
- first power of the roughness.
- square of the velocity.
- inverse square of hydraulic radius.
first power of the roughness.
true ans: square of the velocity.
Out of the following flow measuring devices, which one incurs the maximum installation cost as well as pressure loss ?
- Flow nozzle
- Venturimeter
- Rotameter
- Orificemeter
Venturimeter
true ans: Orificemeter
For turbulent fluid flow in pipe, the expression for Prandtl one seventh power law is (where, r= pipe radius, x = distance).
- V/Vmax = (x/r)^1/7
- V/Vmax = (r/x)^1/7
- V/Vmax = (x.r)^1/7
- none of these
V/Vmax = (x/r)^1/7
Which of the following has the maximum compression ratio ?
- Blower
- Compressor
- Vacuum pump
- Fan
Vacuum pump
true ans: compressor
Scale up of agitator design requires
- geometrical similarity only.
- dynamic similarity only.
- both geometrical and dynamic similarity.
- all geometrical, dynamic and kinematic similarity.
all geometrical, dynamic and kinematic similarity.
Unsteady non-uniform flow is represented by flow through a/an
- long pipe at constant rate.
- long pipe at decreasing rate.
- expanding tube at increasing rate.
- expanding tube at constant rate.
expanding tube at increasing rate.
Prandtl number is a measure of the
- heat conduction to viscosity of a fluid.
- Cp/Cv of a fluid.
- elastic force to pressure force in the fluid flow.
- inertial force to elastic force in the fluid flow.
heat conduction to viscosity of a fluid.
A centrifugal pump has the following specifications:
Power = 4 H.P.; Speed = 800 rpm
Head = 8 metres
Flow = 1000 litres/minutes.
If its speed is halved, then the new head will be __________ metres.
- 2
- 4
- 8
- 5.5
2
In hindered settling, the particles are
- placed farther from the wall.
- not affected by other particles and the wall.
- near each other.
- none of these.
near each other.
A globe valve is the most suitable for applications, in which
- fluid flow control is required.
- fluid contains dispersed solid particles.
- valve is required to be either fully open or fully closed.
- one way flow is required.
fluid flow control is required.
__________ isused for measuring the static pressure exerted on the wall by a fluid flowing parallel to the wall in a pipeline.
- Venturimeter
- Pressure gauge
- Pitot tube
- Orificemeter
Pitot tube
One stoke (unit of kinematic viscosity) is equivalent to
- 1 cm²/second
- 1 m²/second
- 1 gm/cm. second
- 1 kg . m/second
1 cm²/second
Air vessel of a reciprocating pump is initially filled with
- atmospheric air
- compressed air
- water
- none of these
compressed air
The ratio of inertial forces to gravity forces is called the __________ number.
- Mach
- Froude
- Euler
- Weber
Froude
Power required by a centrifugal pump is proportional to (where, D = diameter, N = r.p.m)
- N²D³
- ND²
- N²D
- N³D⁵
N³D⁵
true ans: N²D³
Buckingham-π theorem states that in any physical problem including ‘n’ quantities having ‘m’ diamensions, the quantities can be arranged into __________ independent dimensionless parameters.
- m
- n
- n-m
- n/m
n-m
A fluid which has a linear relationship between the magnitude of applied shear-stress and the resulting rate of deformation is called a/an __________ fluid.
- Newtonion
- Non-Newtonion
- ideal
- incompressible
Newtonion
Existence of boundary layer in fluid flow is because of the
- surface tension
- fluid density
- fluid viscosity
- gravity forces
fluid viscosity
In case of laminar flow of fluid through a circular pipe, the
- shear stress over the cross-section is proportional to the distance from the surface of the pipe.
- surface of velocity distribution is a paraboloid of revolution, whose volume equals half the volume of circumscribing cylinder.
- velocity profile varies hyperbolically and the shear stress remains constant over the cross-section.
- average flow occurs at a radial distance of 0.5 r from the centre of the pipe (r = pipe radius).
surface of velocity distribution is a paraboloid of revolution, whose volume equals half the volume of circumscribing cylinder.
For an ideal fluid flow, Reynolds number is
- 2100
- 100
- 0
- ∞
∞
true ans: 0
Stoke’s equation is valid in the Reynolds number range
- 0.01 to 0.1
- 0.1 to 2
- 2 to 10
- 10 to 100
0.01 to 0.1
true ans: 0.1 to 2
When a fluid flows over a solid surface, the
- velocity is uniform at any cross-section.
- velocity gradient is zero at the solid surface.
- resistance between the surface & the fluid is lesser as compared to that between the fluid layers themselves.
- velocity is not zero at the solid surface.
velocity gradient is zero at the solid surface.
true ans: resistance between the surface & the fluid is lesser as compared to that between the fluid layers themselves.
Pick out the wrong statement about cavitation.
- Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation.
- Cavitation may be caused due to boiling of liquid by decreasing the pressure resulting in formation & collapse of vapor cavities.
- Cavitation begins at higher static pressure and lower velocity in larger diameter pipelines resulting in audible noise.
- Large scale cavitation can not damage pipeline, restrict fluid flow and damage steam turbine blades.
Large scale cavitation can not damage pipeline, restrict fluid flow and damage steam turbine blades.
The maximum delivery pressure of a reciprocating compressor may be about __________ kg/cm².
- 1000
- 2000
- 3000
- 4000
4000
true ans: 1000
The velocity for subsonic flow in a pipeline
- increases in the downstream direction.
- is constant.
- decreases in the downstream direction.
- is independent of the area of flow.
increases in the downstream direction.
Permanent pressure loss in a well designed venturimeter is about __________ percent of the venturi differential.
- 1
- 10
- 30
- 50
10
The ratio of pressure forces to inertial forces is called the __________ number.
- Froude
- Euler
- Reynold
- Mach
Euler
Bernoulli’s equation for fluid flow is derived following certain assumptions. Out of the assumptions listed below, which set of assumptions is used in derivation of Bernoulli’s equation ?
A. Fluid flow is frictionless & irrotational.
B. Fluid flow is steady.
C. Fluid flow is uniform & turbulent.
D. Fluid is compressible.
E. Fluid is incompressible.
- A, C, D
- B, D, E
- A, B, E
- A, D, E
A, B, E
For flow through a venturi at a particular discharge, the correct relationships among heads at points X, Y, and Z are
- h1 > h2 < h3
- h1 > h2 > h3
- h2 < h1 < h3
- h1 < h2 < h3
h1 > h2 < h3
The time of oscillation of a floating body is
- longer, if metacentric height is increased.
- independent of the metacentric height.
- dependent on the buoyant forces only.
- none of these.
none of these.
true ans: longer, if metacentric height is increased.
What is the value of Fanning friction factor f ‘ for smooth pipe at NRe = 10⁶ approximately?
- 0.003
- 0.01
- 0.1
- 0.3
0.003
The hydraulic radius for flow in a rectangular duct of cross-sectional dimension H, W is
- √(HW/π)
- HW/ [2(H+W)²]
- HW / [4(H+W)²]
- 2HW/ (H+W)
HW/ [2(H+W)²]
A tube is specified by its
- thickness only
- outer diameter only
- thickness & outer diameter both
- inner diameter
thickness & outer diameter both
Uniform fluid flow occurs, when the derivative of the flow variables satisfy the following condition.
- ∂/∂t = 0
- ∂/∂t = constant
- ∂/∂s = 0
- ∂/∂s = constant
∂/∂s = 0
true ans: ∂/∂t = 0
The hydraulic diameter of an annulus of inner and outer radii Ri and Ro respectively is
- 4(Ro-Ri)
- √(Ro-Ri)
- 2(Ro-Ri)
- Ro + Ri
2(Ro-Ri)
Ratio of inertial forces to surface tension forces is called the __________ number.
- Euler
- Froude
- Mach
- Weber
Weber
In open channel flow in a rectangular channel, the ratio between the critical depth and the initial depth, when a hydraulic jump occurs is
- 0.5
- 0.84
- 1.84
- 1.25
1.84
The ratio of inertial forces to viscous forces is called the __________ number.
- Weber
- Mach
- Froude
- Reynold
Reynold
Enamels and paints are generally __________ fluid.
- reheopectic
- pseudo-plastic
- thixotropic
- dilatant
pseudo-plastic
With the increase in depth, the hydrostatic pressure in an unaccelerated incompressible fluid (in a constant gravitational field)
- decreases.
- increases linearly.
- increases exponentially.
- remains constant.
increases linearly.
Flow measurement in an open channel is done by a/an
- venturimeter
- orificemeter
- weir
- rotameter
weir
The equivalent diameter for fluid flow through square cross section channel of side ‘x’, for pressure drop calculation purpose is given by
- 4x
- 2x
- x
- √x
x
Hydraulic radius of 6” x 12” cross-section, is __________ inches.
- 2
- 0.5
- 1.5
- none of these
2
Which of the following equations is valid for laminar flow of a fluid through packed bed?
- Fanning equation
- Kozney - Karman equation
- Hagen-Poiseuille equation
- Blake-Plummer equation
Kozney - Karman equation
A pipe has a porous section of length L as shown in the figure. Velocity at the start of this section of V0. If fluid leaks into the pipe through the porous section at a volumetric rate per unit area q(x/L)2, what will be axial velocity in the pipe at any x ? Assume incompressible one dimensional flow i.e., no gradients in the radial direction.
- vₓ = v₀ + q (x³/L²D)
- vₓ = v₀ + (1/3)q (x³/L²)
- vₓ = v₀ + 2q (x³/LD)
- vₓ = v₀ + (4/3)q (x³/L²D)
vₓ = v₀ + (4/3)q (x³/L²D)
Forces acting on a particle settling in fluid are __________ forces.
- gravitational & buoyant.
- centrifugal & drag.
- gravitational or centrifugal buoyant drag.
- external, drag & viscous.
gravitational or centrifugal buoyant drag.
true ans: gravitational & buoyant.
For a fluid rotating at constant angular velocity about vertical axis as a rigid body, the pressure intensity varies as the
- square of the radial distance.
- radial distance linearly.
- inverse of the radial distance.
- elevation along vertical direction.
square of the radial distance.
In a dry packed bed, the pressure drop will be changed by increasing the flow rate as
- V^1.8
- V^-0.8
- V
- V^-1
V^1.8
Specific speed of a centrifugal pump depends upon the __________ head.
- suction
- delivery
- manometric
- none of these
none of these
true ans: manometric
The maximum discharge through a circular channel takes place, when the depth of the fluid flow is __________ times the pipe diameter.
- 0.25
- 0.5
- 0.66
- 0.95
0.95
When the head pumped against is less than the head of the fluid used for pumping, the usual device is a/an
- ejector
- blower
- injector
- airlift
airlift
true ans: ejector
Two fluids are flowing through two similar pipes of the same diameter. The Reynold’s number is same. For the same flow rate if the viscosity of a fluid is reduced to half the value of the first fluid, the pressure drop will
- increase
- decrease
- remain unchanged
- data insufficient to predict relative pressure drop.
decrease
A lubricant 100 times more viscous than water would have a viscosity (in Pa.s)
- 0.01
- 0.1
- 1
- 10
0.1
Nominal Pipe Size (NPS) of a pipe less than 12 inches in diameter indicates its
- inner diameter
- outer diameter
- thickness
- neither inner nor outer diameter
neither inner nor outer diameter
Two liquids manometer is used for measuring small pressure differences in
- liquids
- gases
- mixture of hydrocarbons
- none of these
gases
The pump used for irrigation purposes is generally designed for
- large capacity & high head.
- large capacity & low head.
- small capacity & high head.
- small capacity & low head.
large capacity & low head.
In centrifugal pumps, cavitation occurs, when pressure of the impeller eye or vane becomes
- less than atmospheric pressure.
- more than liquid vapor pressure.
- less than liquid vapor pressure.
- more than atmospheric pressure.
less than liquid vapor pressure.
Viscosity of a liquid decreases __________ with rise in temperature.
- exponentially
- linearly
- logarithmically
- none of these
logarithmically
true ans: exponentially
In case of a pipe of constant cross-sectional area, the maximum fluid velocity obtainable is
- the velocity of sound.
- dependent on its cross-sectional area.
- dependent on fluid viscosity.
- dependent on fluid density.
the velocity of sound.
Discharge in laminar flow through a pipe varies
- as the square of the radius.
- inversely as the pressure drop.
- inversely as the viscosity.
- as the square of the diameter.
as the square of the radius.
The lift of a ballon is
- increased, as it rises to a higher altitude.
- due to the weight of the atmospheric air, that it displaces.
- not dependent on the temperature of the atmosphere.
- none of these.
due to the weight of the atmospheric air, that it displaces.
In which of the following body shapes, the pressure drag is large compared to the friction drag ?
- Stream line body
- Two dimensional body
- Bluff body
- None of these
Bluff body
Major loss in sudden contraction in pipe flow is due to
- boundary friction.
- flow contraction.
- expansion of flow after sudden contraction.
- none of these.
flow contraction.
Which of the following can be used to create a flow of gas, where no significant compression is required ?
- Reciprocating compressor
- Blower
- Axial flow compressor
- Centrifugal compressor
Blower
The ratio of actual discharge to theoretical discharge through an orifice is equal to
- Cc . Cv
- Cc . Cd
- Cv . Cd
- Cd/Cv
Cc . Cv
true ans: Cc . Cd
A free jet of water of cross-sectional area 0.01m2 and a velocity of 20 m/s strikes a plate and then flows in a plane parallel to the plate as shown in the figure below. The horizontal component of the force on the support is
- 200 N
- 400 N
- 2000 N
- 4000 N
4000 N
Which of the following is a Newtonian fluid?
- Rubber latex
- Sewage sludge
- Quicksand
- Non-colloidal solution
Non-colloidal solution
Which of the following valves will incur maximum pressure drop for the same discharge of water ?
- Globe valve
- Gate valve
- Needle valve
- Butterfly valve
Needle valve
Pressure drop in a fluidised bed reactor is __________ that in a similar packed bed reactor.
- less than
- more than
- same as
- none of these
more than
true ans: less than
In deriving Bernoulli’s equation, fluid is assumed to be
- incompressible, frictionless, steady, along a streamline.
- uniform, steady, incompressible, along a streamline.
- steady, density being pressure dependent, frictionless.
- none of these.
incompressible, frictionless, steady, along a streamline.
Unit of mass velocity is
- kg/hr
- kg/m^2. hr
- kg/m^2
- kg/m^3. hr
kg/m^2. hr
true ans: kg/m^2
With increase in molecular weight of the gas, the head developed by a centrifugal compressor will
- decrease
- increase
- remain same
- unpredictable
decrease
Pressure difference between two points in vessels, pipelines or in two different pipelines can be measured by a differential manometer. The pressure difference measured as the mm of water coloumn in case of mercury-water, differential manometer is equal to (where, H = difference in height of mercury column in mm).
- H
- 12.6 H
- 13.6 H
- 14.6 H
12.6 H
true ans: 13.6 H
Low specific speed of a pump implies that, it is a/an __________ pump.
- axial flow
- centrifugal
- mixed flow
- none of these
centrifugal
Pressure drop for laminar fluid flow through a circular pipe is given by
- 4f · (L/D) · (v²/2g꜀) · ρ
- 32 [(μLV)/(g꜀D²)]
- 16/NRe
- (fLρ/D) · (v²/2g꜀)
32 [(μLV)/(g꜀D²)]
For pumping slurry, one can use a __________ pump.
- reciprocating
- diaphargm
- centrifugal
- pneumatic
diaphargm
Which law/principle of solid mechanics is similar/equivalent to Newton’s law of viscosity in fluid mechanics ?
- Archimedes principle.
- Newton’s second law of motion.
- Hooke’s law.
- Newton’s third law of motion.
Hooke’s law.
When larger particles e.g., grains are subjected to fluidisation, the corresponding bed produced is termed as the __________ bed.
- spouted
- sluggish
- boiling
- teeter
spouted
Minimum fluidisation velocity for a specific system depends upon the
- particle size.
- fluid viscosity.
- density of both the particle & the fluid.
- all (a), (b) and (c).
all (a), (b) and (c).
Potential flow is characterised by the
- irrotational and frictionless flow.
- irrotational and frictional flow.
- one in which dissipation of mechanical energy into heat occurs.
- formation of eddies within the stream.
irrotational and frictionless flow.
For the production of very high vacuum, a __________ pump is normally used.
- diffusion
- centrifugal
- jet ejector
- piston
diffusion
In parallel pipe problems, the
- head loss is the same through each pipe.
- discharge is the same through all the pipes.
- total head loss is equal to the sum of the head losses through each pipe.
- none of these.
head loss is the same through each pipe.
Fluid flow through a packed bed is represented by the __________ equation.
- Fanning’s
- Ergun’s
- Hagen-Poiseuille’s
- none of these
Ergun’s
__________ is an example of axial flow impeller.
- Paddle
- Turbine
- Propeller
- all (a), (b) and(c)
Propeller
If three pipes of different diameters, lengths & friction factors are connected in parallel, then (where, Q = flow rate, V= fluid velocity f = friction factor).
- Q = Q1 + Q2 + Q3
- V1 = V2 = V3
- Q1 = Q2 = Q3
- f = f1 + f2 + f3
Q = Q1 + Q2 + Q3
Horsepower requirement for given pump capacity depends upon the
- specific gravity of the liquid
- suction lift
- discharge head
- all (a), (b) and (c)
all (a), (b) and (c)
Bernoulli’s equation accounts for the
- various momentums
- various masses
- different forms of mechanical energy
- none of these
different forms of mechanical energy
Plunger pumps are used for
- higher pressure
- slurries
- viscous mass
- none of these
higher pressure
What is the ratio of displacement thickness to nominal thickness for a linear distribution of velocity in the boundary layer on a flat plate ?
- 0.5
- 1
- 1.5
- 2
0.5
In turbulent flow, the
- fluid particles move in an orderly manner.
- momentum transfer is on molecular scale only.
- shear stress is caused more effectively by cohesion than momentum transfer.
- shear stresses are generally larger than in a similar laminar flow.
shear stresses are generally larger than in a similar laminar flow.
Momentum correction factor used in fluid flow problems accounts for the
- change in direction of flow.
- change in total energy.
- change in pressure.
- non uniform direction of velocities at inlet & outlet sections.
non uniform direction of velocities at inlet & outlet sections.
Drag co-efficient for motion of spherical particles in a stationary fluid in the stoke’s law range is
- 24/NRe,p
- 16/NRe,p
- 64/NRe,p
- 48/NRe,p
24/NRe,p
Design of the casing of centrifugal pump should be such as to minimise the
- back flow through impeller
- loss of kinetic head
- loss of static head
- none of these
loss of kinetic head
Which of the following is used for pumping crude oil from oil well ?
- Single stage centrifugal pump
- Gear pump
- Screw pump
- Duplex/triplex reciprocating pump
Duplex/triplex reciprocating pump
The energy loss in flow through ven-turimeter is less than that through flow nozzle, because in case of a flow nozzle, the
- length is shorter.
- throat diameter is more.
- sudden expansion of flow in the downstream occurs.
- distance between the throat and the inlet is more.
sudden expansion of flow in the downstream occurs.
__________ flow means the flow of incompressible fluid with no shear.
- Potential
- Streamline
- Creep
- Boundary layer
Potential
The continuity equation
- relates mass flow rate along a stream tube.
- relates work and energy.
- stipulates that Newton’s second law of motion must be satisfied at every point in the fluid.
- none of these.
relates mass flow rate along a stream tube.
The energy loss over a length of pipeline according to Darcy-Weisbach equation for pipe flow is ______ the mean velocity of flow.
- directly proportional to
- directly proportional to square of
- inversely proportional to
- inversely proportional to square of
directly proportional to square of
Pressure drop in a packed bed for laminar flow is given by the __________ equation.
- Kozney-Karman
- Blake-Plummer
- Leva’s
- Fanning friction factor
Kozney-Karman
The fluid velocity varies as the cube of the cylinderical pipe diameter in case of steady state laminar flow at constant pressure drop for __________ fluid.
- Newtonion
- pseudoplastic
- dilatent
- Bingham plastic
pseudoplastic
Stoke’s law is valid, when NRe, p is less than
- 2
- 100
- 2100
- 700
2
true ans: 2100
Froude number is the ratio of
- shear stress to gravitational stress.
- drag stress to shear stress.
- inertial stress to shear stress.
- inertial stress to gravitational stress.
inertial stress to gravitational stress.
Normal depth in open channel flow is the depth of flow in the channel
- corresponding to uniform flow.
- measured normal to the channel bed.
- corresponding to steady flow.
- none of these.
corresponding to uniform flow.
Which of the following flow measuring devices is an area meter ?
- Venturimeter
- Orifice meter
- Anemometer
- Rotameter
Rotameter
With decrease in particle size to be fluidised by a particular fluid, the operating range of fluidisation velocity
- widens
- squeezes
- does not change
- unpredictable from the data
does not change
true ans: widens
Diaphragm valves are used for handling __________ fluids.
- corrosive
- viscous
- non-Newtonion
- solid suspended
corrosive
The schedule number of a pipe is an indication of its
- size
- roughness
- material density
- wall thickness
wall thickness
Minimum porosity for fluidisation is
- that corresponding to static bed.
- that corresponding to completely fluidised bed.
- the porosity of the bed when true fluidisation begins.
- less than that of the’ static bed.
the porosity of the bed when true fluidisation begins.
A centrifugal pump used to pump water is used to pump an oil with specific gravity of 0.8 at the same rate. The power consumption will now
- increase
- decrease
- remain same
- data insufficient to predict
decrease
Steady non-uniform flow is exemplified by flow through a/an
- long pipe at constant rate.
- long pipe at decreasing rate.
- expanding tube at increasing rate.
- expanding tube at constant rate.
expanding tube at constant rate.
Hot wire anemometer is used to measure the
- velocity of liquids.
- temperature of liquids.
- velocity of gases.
- pressure of liquids.
velocity of gases.
Propeller type centrifugal pumps are most suitable for
- high capacity at high heads.
- high capacity at low heads.
- low capacity at high heads.
- low capacity at low heads.
high capacity at low heads.
The fluid velocity varies as the square of the cylindrical pipe diameter, in case of steady state laminar flow at constant pressure drop, for __________ fluid.
- Newtonion
- dilatant
- pseudoplastic
- non-Newtonion
Newtonion
Momentum transfer in laminar flow of fluids results due to the
- viscosity
- density
- velocity gradient
- none of these
velocity gradient
Diaphragm pumps are used to transport
- solids
- liquids
- fluids
- slurries
slurries
For steady ideal fluid flow, the Bernoulli’s equation states that the
- velocity is constant along a stream line.
- energy is constant throughout the fluid
- energy is constant along a stream line, but may vary across stream lines
- none of these
energy is constant along a stream line, but may vary across stream lines
In case of a centrifugal pump, the theoretical head developed is dependent on the __________ the impeller.
- speed of
- diameter of
- fluid velocity leaving
- all (a), (b) and (c)
all (a), (b) and (c)
Choose the set of pressure intensities that are equivalent.
- 4.33 psi, 10 ft. of water, 8.83 inches of Hg.
- 4.33 psi, 10 ft. of water, 20.7 inches of Hg.
- 10 psi, 19.7 ft. of water, 23.3 inches of Hg.
- 10 psi, 19.7 ft. of water, 5.3 inches of Hg.
4.33 psi, 10 ft. of water, 8.83 inches of Hg.
Hydraulic mean radius for flow through packed bed of spherical particle of size, ‘Dp, with porosity ‘ε’ is
- (Dp/6) (ε/1-ε)
- (Dp/6) (1-ε/ε)
- (2/3)Dp · (1-ε/ε)
- (2/3)Dp · (ε/1-ε)
(Dp/6) (ε/1-ε)
Pick out the wrong statement about a streamline.
- It is always parallel to the main direction of the fluid flow.
- It is a line across which there is no flow and it is equivalent to a rigid boundary.
- Streamlines intersect at isolated point of zero velocity and infintie velocity.
- The fluid lying between any two streamlines can be considered to be in isolation and the streamline spacing varies inversely as the velocity.
It is always parallel to the main direction of the fluid flow.
The most serious disadvantage of an orificemeter is that
- it is not very accurate.
- it is very costly.
- most of the pressure drop is not recoverable.
- it is not suitable for measuring gas flow.
most of the pressure drop is not recoverable.
The discharge through a rectangular weir varies as
- H^1/2
- H^5/2
- H^2/5
- H^3/2
H^3/2
In case of supersonic flow of a fluid through pipeline, the ‘Mach number’ is
- 0
- 1
- < 1
- > 1
- > 1
Transition length for turbulent flow in smooth pipe is equal to __________ times the pipe diameter.
- 0.5
- 5
- 50
- 100
50
Disc compensators are provided in large diameter fuel gas carrying pipelines to
- keep the pipe in proper orientation.
- make the pipe joint leak-proof.
- account for contraction/expansion of pipe due to temperature changes of the surroundings.
- account for the pressure variation side the pipeline.
account for contraction/expansion of pipe due to temperature changes of the surroundings.
Paper pulp is an example of __________ fluid.
- dilatant
- bingham plastic
- Newtonion
- pseudoplastic
bingham plastic
The ratio of the depth of flow to the diameter of the channel for maximum discharge in a circular channel in open channel flow is
- 0.1
- 0.55
- 0.95
- 1.85
0.95
A conical tank with a bottom opening of cross-sectional area A is filled with water and is mounted on supports as shown in the figure. What is the force F with which plate X must be pushed up to prevent water from leaking ? Assume that the density of air is negligible as compared to the density of water ρL.
- ρL . Vg
- ρL . A.Hg
- ρL . Vg/2
- ρL .Vg/3
ρL . A.Hg
A relief valve
- provides back pressure for a cylinder.
- unloads a pump.
- is a directional control valve.
- none of these.
is a directional control valve.
true ans: unloads a pump.
An isentropic process is the one, in which
- pv = constant
- pvʳ = constant
- pvʳ = constant, and process is reversible
- none of these
pvʳ = constant, and process is reversible
The distribution of shear stress in a stream of fluid in a circular tube is
- linear with radius for turbulent flow only.
- linear with radius for laminar flow only.
- linear with radius for both laminar & turbulent flow.
- parabolic with radius for both laminar & turbulent flow.
linear with radius for both laminar & turbulent flow.
true ans: linear with radius for laminar flow only.
For motion of spherical particles in a stationary fluid, the drag co-efficient in hindered settling compared to that in free settling is
- more
- less
- equal
- more or less, depending on the type of particle
more
Specific speed of a centrifugal pump relates it with another pump having the
- dynamic similarity
- same efficiency
- same speed
- geometrical similarity
dynamic similarity
Air vessel fitted to a reciprocating pump
- increases the work done.
- decreases the work done.
- causes cavitation.
- results in non-uniform discharge.
decreases the work done.
Deformation drag, which is caused by widespread deformation of fluid around the immersed body
- occurs when NRe is very small.
- is primarily a friction drag.
- is independent of body length.
- depends mainly on cross-sectional shape.
occurs when NRe is very small.
true ans: depends mainly on cross-sectional shape.
In isotropic turbulence, the __________ are equal to each other.
- temporal velocity components
- mean square of velocity fluctuations in the three co-ordinate directions
- root mean square of velocity fluctuations in the three co-ordinate directions
- none of these
mean square of velocity fluctuations in the three co-ordinate directions
Viscosity of water is about __________ times that of air at room temperature.
- 15
- 55
- 155
- 1050
55
In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow?
- Discharge of water by a centrifugal pump being run at a constant rpm.
- Water flow in the suction and discharge pipe of a reciprocating pump.
- Water discharge from a vertical vessel in which constant level is maintained.
- Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe.
Water flow in the suction and discharge pipe of a reciprocating pump.
Nature of fluid flow during the opening of a valve in a pipeline is
- laminar
- unsteady
- steady
- uniform
unsteady
The __________ pressure is measured by a static tube.
- dynamic
- static
- total
- none of these
static
The speed of a sound wave in a gas is analogous to the speed of
- an elementary wave in an open channel.
- flow in an open channel.
- a disturbance travelling upstream in moving fluid.
- none of these.
an elementary wave in an open channel.
true ans: a disturbance travelling upstream in moving fluid.
A spherical particle is falling slow in a viscous liquid such that Reynolds number is less than 1. Which statement is correct for this situation ?
- Inertial and drag forces are important.
- Drag, gravitational and buoyancy forces are impportant.
- Drag force and gravitational forces are important.
- None of the above.
Drag, gravitational and buoyancy forces are impportant.
Which of the following is not dimension-less?
- Froude number
- Kinematic viscosity
- Pressure co-efficient
- None of these
Kinematic viscosity
In laminar flow through a round tube, the discharge varies
- linearly as the viscosity.
- inversely as the pressure drop.
- inversely as the viscosity.
- as the square of the radius.
inversely as the viscosity.
Which is not a variable head meter ?
- Venturimeter
- Pitot tube
- Rotameter
- None of these
Rotameter
The pipe wall thickness is minimum for a pipe of given nominal size having schedule number
- 160
- 120
- 80
- 40
40
Reynolds number for flow of water at room temperature through 2 cm dia pipe at an average velocity of 5 cm/sec is around
- 2000
- 10
- 100
- 1000
1000
Centrifugal pumps as compared to reciprocating pumps
- run at a lower speed for the same discharge.
- do not need priming.
- deliver fluid with pulsating/fluctuating discharge.
- can be run with discharge line valve closed for a short interval.
can be run with discharge line valve closed for a short interval.
What type of motion the fluid element undergoes, when it changes from one position to another position, such that the angle between the two sides change ?
- Rotation
- Translation
- Linear deformation
- Angular deformation
Angular deformation
The continuity equation in ideal fluid flow states that
- net rate of inflow into any small volume must be zero.
- energy is not constant along a streamline.
- energy is constant along a streamline.
- there exists a velocity potential.
net rate of inflow into any small volume must be zero.
Bernoulli’s equation is not applicable, when the flow is
- irrotational.
- incompressible.
- viscous.
- all (a), (b) & (c).
all (a), (b) & (c).
The equivalent diameter for pressure drop calculation for a duct of square cross-section is given by(where, x = each side of the square duct)
- x
- √ (πx)
- √ (2x)
- √ (x/2)
x
Centre of pressure of a plane surface of arbitrary shape immersed vertically in a static mass of fluid
- lies above the centroid of the plane surface.
- is independent of the specific weight of the fluid.
- is different for different fluids.
- is at the centroid of the plane surface.
is independent of the specific weight of the fluid.
Drag co-efficient for flow past immersed body is the ratio of __________ to the product of velocity head and density.
- shear stress
- shear force
- average drag per unit projected area
- none of these
average drag per unit projected area
Creeping flow around a sphere is defined, when particle Reynolds number is
- < 2100
- < 0.1
- > 2.5
- < 500
< 0.1
Open channel liquid flow is most conveniently measured by a
- hot wire anemometer
- notch
- rotameter
- segmental orifice
notch
Toothpaste is a
- Bingham plastic
- pseudoplastic
- Newtonion liquid
- dilatent
dilatent
true ans: Bingham plastic
Volute type of casing is provided in a centrifugal pump to
- convert velocity head to pressure head.
- convert pressure head to velocity head,
- reduce the discharge fluctuation.
- increase the discharge.
increase the discharge.
true ans: convert velocity head to pressure head.
Each term of the Bernoulli’s equation written in the form, (p/ρ)+ (g/gc)·Z + (v²/2gc) , represents the total energy per unit
- mass
- volume
- specific weight
- none of these
mass
In a free vortex, the
- velocity changes linearly with radial distance.
- flow is necessarily rotational.
- radial component of velocity is same everywhere.
- stream lines are not circular.
velocity changes linearly with radial distance.
true ans: radial component of velocity is same everywhere.
Pick out the wrong statement.
- The eddy viscosity is a function of the type of turbulence involved.
- The eddy viscosity is a fluid property.
- The viscosity of gas increases with increase in temperature.
- The viscosity of a liquid increases with decrease in temperature.
The eddy viscosity is a fluid property.
The velocity distribution in direction normal to the direction of flow in plane Poiseuille flow is
- hyperbolic
- parabolic
- linear
- none of these
parabolic
In fluid flow, the stagnation point is defined as a point, where the __________ is zero.
- flow velocity
- pressure
- total energy
- all (a), (b) and (c)
flow velocity
A special type of liquid transporting device is the diffuser pump, in which __________ are minimised.
- bearing losses
- disk friction
- shock losses
- cavitation
shock losses
Which of the following is most prone to pulsating discharge flow ?
- Centrifugal pump
- Reciprocating pump
- Gear pump
- Axial flow pump
Gear pump
true ans: Reciprocating pump
A streamline is
- the line connecting the mid-points of flow cross-sections.
- defined for uniform flow only.
- drawn normal to the velocity vector at every point.
- always the path of a particle.
drawn normal to the velocity vector at every point.
true ans: always the path of a particle.
Which of the following relationship is valid for the equilibrium position of the float in a rotameter ?(where, Df= Drag force on the float Bf = Buoyant force on the float Wf = Weight of the float)
- Df + Bf = Wf
- Df = Bf + Wf
- Df + Bf + Wf =0
- none of these
Df + Bf = Wf
Drag is defined as the force exerted by the
- fluid on the solid in a direction opposite to flow.
- fluid on the solid in the direction of flow.
- solid on the fluid.
- none of these.
fluid on the solid in a direction opposite to flow.
The boundary layer is that part of a moving fluid, in which the fluid velocity is
- affected by the fluid flow pressure.
- constant.
- affected by the presence of a solid boundary.
- all (a), (b) and (c).
affected by the presence of a solid boundary.
The terminal velocity of a solid spherical particle falling through a stationary fluid mass in the Stoke’s law range is proportional to the
- inverse of fluid viscosity.
- square of particle size.
- difference in the densities of the particle & fluid.
- all (a), (b) and (c).
all (a), (b) and (c).
Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (ε0) with age/time (t) (where, ε = roughness of the surface after time’t’. α = a co-efficient to be experimentally determined)?
- ε = ε₀ + α.t
- ε = ε₀ + α.t²
- ε = ε₀ + α.t³
- ε = ε₀ + α.t⁴
ε = ε₀ + α.t
Fluidised beds are formed, when the
- fluid friction is zero
- gravity force is less than the fluid friction.
- pressure forces equal gravity forces.
- sum of the fluid friction and pressure forces is equal and opposite to gravity forces.
gravity force is less than the fluid friction.
true ans: sum of the fluid friction and pressure forces is equal and opposite to gravity forces.
A fluid is pumped at the rate of 10 lb/sec to a height of 55 ft. The horse power required is __________ hp.
- 1
- 10/55
- 5.5
- 1/55
1
Pick out the wrong statement:
- The vacuum pressure is always the negative gauge pressure.
- The pressure of the liquid measured by a piezometer tube is the gauge pressure.
- Manometric liquid should have high surface tension.
- The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity.
The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity.
In a fully turbulent flow (Re > 105) in a pipe of diameter ‘d’, for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is
- d
- d^2
- d^2.5
- d^4
d^2.5
Pump used for the transportation of molten sodium in a fast breader reactor is a/an __________ pump.
- reciprocating
- plunger
- electromagnetic
- gear
electromagnetic
Small pressure differences in liquids is measured using a/an
- U-tube manometer.
- inclined tube manometer.
- pitot tube.
- none of these.
inclined tube manometer.
With increase in pump speed, its NPSH requirement
- decreases
- increases
- remains unaltered
- can either increase or decrease ; depends on other factors
increases
In the Newton’s law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass is __________ the fluid viscosity.
- directly proportional to
- inversely proportional to
- inversely proportional to the square root of
- independent of
inversely proportional to
Gear pump
- is a positive displacement pump.
- is a centrifugal pump.
- is a non-positive displacement pump.
- can be started with delivery valve closed.
is a positive displacement pump.
Most of the centrifugal pumps used in chemical plants are usually __________ driven.
- steam
- diesel engine
- electric motor
- gas turbine
electric motor
Check valve provided in the discharge line of a centrifugal pump serves the purpose of controlling the
- back flow of fluid in the event of stoppage of pump.
- discharge pressure.
- flow of liquid during operation of the pump.
- all (a), (b) and (c).
back flow of fluid in the event of stoppage of pump.
Venturimeters, orificemeters and nozzles are used to measure the fluid discharge from a pipeline. The average fluid velocity in a pipeline can be measured by a/an
- weir
- hot wire anemometer
- cup and vane aneometer
- none of these
hot wire anemometer
true ans: none of these
The time taken for gravity flow of a fixed volume of liquid (as in Redwood viscometer) is directly proportional to its
- absolute viscosity.
- ratio of absolute viscosity to density.
- density.
- Reynolds number.
ratio of absolute viscosity to density.
The exit cone angle in case of a standard venturimeter is __________ the entrance cone angle.
- smaller than
- greater than
- equal to
- either (a) or (b)
smaller than
true ans: greater than
Sewage sludge is __________ type of non-Newtonion fluid.
- dilatant
- Bingham plastic
- Pseudo plastic
- none of these
Bingham plastic
Ratio of pressure and inertia force gives __________ number.
- Weber
- Mach
- Euler
- Froude
Euler
Permanent loss in a venturimeter is about __________ percent of the pressure drop in the upstream cone.
- 1
- 10
- 40
- 70
10
Volume of liquid displaced by a floating body is equivalent to its
- own weight
- submerged weight
- own volume
- submerged volume
own weight
true ans: submerged volume
The __________ is measured by a piezometric opening.
- dynamic pressure
- static pressure
- total pressure
- point velocity
total pressure
true ans: static pressure
What is the pipe called which lifts water from a reservoir to a greater height than the initial level in the supply reservoir ?
- Penstock
- Siphon
- Tunnel
- Pressure pipeline
Siphon
Steady uniform flow is represented by flow through a/an
- long pipe at constant rate.
- long pipe at decreasing rate.
- expanding tube at constant rate.
- none of these.
long pipe at constant rate.
Pick out the correct statement pertaining to the flow through a converging-diverging tube.
- The value of Mach number is always unity at the throat.
- No shock wave develops in the tube when the Mach number at exit is greater than unity.
- Throughout the converging portion of the tube, the density increases in the downstream direction.
- none of these.
No shock wave develops in the tube when the Mach number at exit is greater than unity.
Cavitation can be prevented by
- suitably designing the pump.
- maintaining the suction head sufficiently greater than the vapour pressure.
- maintaining suction head = developed head.
- maintaining suction head lower than the vapour pressure.
maintaining the suction head sufficiently greater than the vapour pressure.
Assuming flow to be laminar, if the diameter of the pipe is halved, then the pressure drop will
- increase
- decrease
- remain same
- be quadrupled
increase
Steady flow occurs, when the
- conditions change steadily with time.
- conditions are the same at the adjacent points at any instant.
- conditions do not change with time at any point.
- rate of the velocity change is constant.
conditions do not change with time at any point.
With increase in the ratio of orifice diameter to pipe diameter, the fraction of the orifice pressure differential that is permanently lost
- increases
- decreases
- remains unchanged
- increases exponentially
decreases
Which of the following two quantities when same, makes one pipe system equivalent to another pipe system ?
- Head & discharge
- Length & discharge
- Length & diameter
- Friction factor & diameter.
Head & discharge
The kinetic energy correction factor for velocity distribution of laminar flow is
- 0.5
- 1.66
- 1
- 2
1.66
true ans: 2
Priming of a centrifugal pump is done to
- increase the mass flow rate of fluid.
- develop effective pressure rise by the pump.
- avoid chances of separation inside the impeller.
- none of these.
avoid chances of separation inside the impeller.
true ans: develop effective pressure rise by the pump.
For pipes that must be broken at intervals for maintenance, the connector used should be a/an
- union
- tee
- reducer
- elbow
union
A fluid is the one, which
- cannot remain at rest under the action of shear force.
- continuously expands till it fills any container.
- is incompressible.
- permanently resists distortion.
cannot remain at rest under the action of shear force.
One horsepower is equal to
550 lbf.ft/second
550 kgf.m/second
both (a) and (b)
550 lbf.ft./hr
550 lbf.ft/second
For one dimensional flow of an incompressible fluid in unsteady state in x-direction, the continuity equation is given by
- ∂u/∂x = 0
- ∂(ρu)/∂x = 0
- ∂u/∂x = - (∂ρ/∂t)
- ∂ρ/∂t = 0
∂u/∂x = 0
true ans: ∂u/∂x = - (∂ρ/∂t)
A fluidis (μ/ρ = 0.01 cm²/sec) is moving at critical flow condition (NRe = 2100) through a pipe of dia 3 cms. Velocity of flow is __________ cm/sec.
- 7
- 700
- 7000
- 630
7
Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, σ = surface tension of mercury)
- d
- 1/d
- σ
- l/σ
σ
true ans: 1/d
The pressure drop per unit length of pipe incurred by a fluid ‘X’ flowing through pipe is Δp. If another fluid ‘Y’ having both the specific gravity & density just double of that of fluid ‘X’, flows through the same pipe at the same flow rate/average velocity, then the pressure drop in this case will be
- Δp
- 2Δp
- Δp²
- Δp/2
2Δp
true ans: Δp
In the laminar boundary layer flow over a flat plate, the ratio (δ/x) varies as :(where, ‘δ’ is the boundary layer thickness and ‘x’ is the distance from the leading edge in the direction of flow).
- Re
- √Re
- 1/Re
- Re^-1/2
Re^-1/2
A rotameter through which air at room temperature and atmospheric pressure is flowing gives a certain reading for a flow rate of 100 cc/sec. If helium (molecular weight 4) is used and rotameter shows the same reading, the flow rate (cc/sec) is
- 26
- 42
- 269
- 325
269
A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m³ ) is to be fluidised by water (density 1000 kg/m³ ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is
- 4.4 KPa
- 2.94 KPa
- 3.7 KPa
- none of these
4.4 KPa
Select the wrong statement pertaining to flow of an incompressible fluid through a venturimeter.
- For frictionless flow, the fluid pressure entering the venturi meter will be exactly equal to that leaving the venturimeter.
- Discharge of fluid through a venturimeter depends upon the gage difference irrespective of the orientation of venturimeter.
- Venturimeter occupies less space than an orificemeter.
- Venturimeter incurs less power loss compared to an equivalent orificemeter.
Venturimeter occupies less space than an orificemeter.
Reynolds number for water flow through a tube of I.D. 5 cm is 1500. If a liquid of 5 centipoise viscosity and 0.8 specific gravity flows in the same pipe at the same velocity, then the pressure drop will
- increase
- decrease
- remain same
- data insufficient to predict pressure drop
increase
The bulk modulus of elasticity of a liquid
- is zero for incompressible liquid.
- decreases with pressure.
- is independent of temperature & pressure.
- increases with pressure.
increases with pressure.
The inherent characteristic of an equal percentage valve relating flow rate ‘q’ with valve stem movement ‘x’ are described by the equation
- dq/dx = K
- dq/dx = K·q
- dq/dx = K/q
- dq/dx = K·q²
dq/dx = K
true ans: dq/dx = K·q
What is the ratio of total kinetic energy of fluid passing per second to the value obtained on the basis of average velocity (for laminar flow through a circular pipe)?
- 0.5
- 1
- 1.5
- 2
2
The line traced by a single fluid particle as it moves over a period of time is called __________ line.
- stream
- path
- equipotential
- none of these
path
The pressure head on sudden contraction in a horizontal pipe is converted into the __________ head.
- elevation
- velocity
- both (a) & (b)
- neither (a) nor (b)
velocity
Colebrook equation for friction factor in turbulent flow is given by, f^0.5 = -4 logₑ [(ε/D) + (1.26/NRe√F)] . It reduces to Nikuradse equation for a value of ε/D equal to
- 0
- 1
- ∞
- 0.5
1
true ans: 0
Erosion and pits formation on the impeller of a centrifugal pump may be due to
- cavitation.
- low speed of impeller.
- its operation with delivery valve closed for considerable time after starting the pump.
- off centering of pump with motor.
cavitation.
The velocity profile exhibited by laminar flow of Newtonion fluids is such that the velocity distribution w.r.t. radius of the circular pipe is a/an __________ with the apex at the centre line of the pipe.
- hyperbola
- parabola
- semi-circle
- semi-ellipse
parabola
Piezometric head is the sum of the __________ heads.
- elevation & kinetic energy
- elevation & pressure
- kinetic energy & pressure
- none of these
elevation & pressure
Potential flow is the flow of
- compressible fluids with shear.
- compressible fluids with no shear.
- incompressible fluids with shear.
- incompressible fluids with no shear.
incompressible fluids with no shear.
Mach number is important in a fluid flow problem, when the inertia and __________ forces predominate.
- elastic
- viscous
- gravity
- none of these
elastic
In case of coutte flow, the fluid flow is between two large flat parallel plates with
- top plate moving and the bottom plate fixed.
- bottom plate moving and the top plate fixed.
- both the plates fixed.
- both the plates moving.
top plate moving and the bottom plate fixed.
In a stabilised soap bubble, pressure inside it compared to external pressure is
- more
- less
- same
- unpredictable
more
For a stable equilibrium of a submerged body (where, G and B are centres of gravity & buoyancy respectively).
- G is above B
- B is above G
- B & coincide
- none of these
B is above G
With increase in the ratio of orifice diameter to pipe diameter in case of an orificemeter, the overall pressure loss
- decreases
- increases
- remains constant
- increases linearly
remains constant
true ans: decreases
The discharge through a semi-circular weir varies as (where, H = Head of liquid.)
- H
- H^2
- H^3/2
- H^1/2
H^2
true ans: H^(3/2)
The Mach number for hypersonic flow of compressible fluid is
- 1
- > 1
- > 4
- < 2
- > 4
Boundary layer thickness in turbulent flow over a flat plate increases as (where, d = distance from the leading edge.)
- √d
- d^2/3
- d^4/5
- d^1/3
d^4/5
true ans: d^1/3
f = 16/NRe, is valid for
- turbulent flow
- laminar flow through an open channel
- steady flow
- none of these
none of these
In case of turbulent flow of a Newtonion fluid in a straight pipe, the maximum velocity is equal to (where, Vavg = average fluid velocity)
- Vavg
- 1.2 Vavg
- 1.5 Vavg
- 1.8 Vavg
1.2 Vavg
true ans: 1.5 Vavg
For laminar flow of Newtonion fluids through a circular pipe, for a given pressure drop and length & diameter of pipe, the velocity of fluid is proportional to(where, μ = fluid viscosity )
- μ
- 1/μ
- √μ
- 1/√μ
1/μ
