Fluid Mechanics Part 1 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 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 of these.
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.
The pitot static tube does not measure the __________ pressure.
static
total
difference in static & dynamic
all of these
all of these
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
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
Remember: ratio trapezoidal 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^-6m^2/s).
24000
24
0.24
0.44
0.44
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/Dp^2
Vs^2/Dp^2
Vs^2/Dp^3
Vs/Dp^3
Vs/Dp^2
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)
FL^-1
F^-1 . L
F.L^-2
F^-2 . L
FL^-1
Which of the following is not a dimension-less 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
Remember: 15 34 90 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 of these
all of these
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
Remember: Brownian 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 u = 10 Pa.s and yield stress, T0 = 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
Remember: resistance anemometer 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
Remember: sump single stage vertical
A hydraulic ram acts as a/an __________ pump.
centrifugal
reciprocating
impulse
parallel cylinder
impulse
Remember: hydraulic ram 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^-1L^2T
F^-1L^2T^-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 (1)
In the equation, (1) 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.
Remember: wrong statement Mach number >0.6
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.
Remember: Stoke’s axial
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. https://www.indiabix.com/_files/images/chemical-engineering/fluid-mechanics/61-788-1.png
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 < < 1, accelerating flow
Re > > 1, accelerating flow
Re < < 1, decelerating flow
Re > > 1, decelerating flow
Re > > 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 of these
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.
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.
Remember: Bernoulli dependent none
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
Remembers: Vena-contracta 0.5d
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.
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 fall-ing 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 of these
all of these
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 of these
all of these
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.
Remember: isotropic no velocity gradient
The co-efficient of drag and lift for an incompressible fluid depends on the
Reynolds number
Froude number
Mach number
all of these
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.
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
f^-0.5 = 4.07 loge (NRe sqrt-f)^-0.6
none of these
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 of these
all of these
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.
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/D^2
1/D^5
D^2
1/D^5
The energy equation, E + P/rho + (V^2)/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.
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
Remember: tee more than two branches
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
ME Mach - inertial to Elastic
WS Weber - inertial to Surface tension
FG Froude - inertial to Gravitational
RV Reynold - inertial to Viscous
EP Euler - Pressure to inertial
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/sqrt-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 of these
all of these
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 (1) Cv = co-efficient of velocity (2)
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
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
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, Rand S
P, Q and R
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
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
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 of these
all of these
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(T) with velocity gradientat (dv/dy) constant pressure temperature is shown below in the figure.
https://www.indiabix.com/_files/images/chemical-engineering/fluid-mechanics/49-680-2.png
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 (u = 1 cp) will deliver __________ when pumping a thicker oil (u = 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.
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
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 (delta- P)n, where delta-P 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.
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 rpmHead = 8 metresFlow = 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
L^2T^-1
ML^-2T^-2
none of these
L^2T^-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
5sqrt-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.
N^2Re/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)
2y/3
3y/4
2y/3
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 V^2.
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 of these
all of these
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 of these
all of these
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 ‘delta-p’ with average velocity ‘Vavg’?
D delta-p/8L
D delta-p/4L
8 . Vavg/D
4 . Vavg/D
8 . 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 m^3/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 of these
all of these
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
