Fluid Mechanics Flashcards by . .

The fluid property, due to which, mercury does not wet the glass is

surface tension

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Laminar flow of a Newtonion fluid ceases to exist, when the Reynolds number exceeds

2100

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When the momentum of one fluid is used for moving another fluid, such a device is called a/an

jet pump

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The head loss in turbulent flow in a pipe varies

as (velocity)^2

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Most commonly used joint in the underground pipe lines is the

sleevejoint

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Schedule number of a pipe, which is a measure of its wall thickness, is given by

1000 P’/S

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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

suction minus vapor pressure of the liquid at suction temperature.

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With increasing flow rate, the hydraulic efficiency of a centrifugal pump

monotonically decreases.

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The velocity profile for turbulent flow through a closed conduit is

logarithmic

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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

friction co-efficient for flows at equal Reynold number.

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Water hammer in a pipeline results from the

rapid pressure change due to a rapid change in the rate of flow.

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Molten soap mass is transported by a __________ pump.

centrifugal

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Which of the following denotes the effect of compressibility in fluid flow ?

a. Weber number
b. Mach number
c. Euler number
d. Reynolds number

Mach number

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Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe.

smaller than

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The terminal velocity of a small sphere settling in a viscous fluid varies as the

inverse of the fluid viscosity.

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If the discharge of a centrifugal pump is throttled, then its suction lift

increases

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Foot valves provided in pumps are __________ valves.

directional control

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At high Reynolds number

inertial forces control and viscous forces are unimportant.

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Power loss in an orificemeter is __________ that in a venturimeter.

more than

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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

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What is the normal range of exit cone angle of a venturimeter ?

7 to 15

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The dimension of dynamic viscosity is

ML^-1T^-1

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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

one fourth as that of A.

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The pitot static tube does not measure the __________ pressure.

a. static
b. total
c. difference in static & dynamic
d. all (a), (b) and (c)

all of these

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The fluid in which the shearing stress within it is proportional to the velocity gradient across the sheared section, is called a __________ fluid.

Newtonion

The ratio of the depth of flow to the hydraulic radius for the most economical trapezoidal section, in open channel flow is

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).

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

The maximum delivery pressure of compressors can be upto __________ atmospheres.

1000

Dimension of surface tension is(where, F = force, L = length)

FL^-1

Which of the following is not a dimension-less parameter ? a. Euler number b. Specific gravity c. Fanning friction factor d. None of these

None of these

Co-efficient of velocity is __________ the coefficient of discharge.

more than

All pipes of a particular nominal size have the same

outside diameter

For the transfer of solution of thick slurry, the pump used is a __________ pump.

diaphragm

Which of the following is not concerned with the fluid-particle interaction ? a. Drag co-efficient b. Froude number c. Galileo number d. 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.

Pressure drag does not depend upon the a. roughness of surface of the body. b. pressure of main flow only. c. length of the body in flow direction. d. all (a), (b) and (c)

all of these

Dimension of absolute viscosity is

ML^-1T^-1

__________ pumps are axial flow pumps.

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

For a particle settling in water at its terminal settling velocity, which of the following is true ?

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

20 KPa

Pick out the correct statement. a. A forced vortex occurs when fluid rotates as a solid about an axis. b. laminar flow, Newton's law of viscosity does not apply. c. A free vortex occurs, when fluidrotates as a solid. d. 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

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

tungsten

Two dimensional stream function

is constant along a stream line.

What causes cavitation in centrifugal pump ?

Low suction pressure

Draining of shallow pits or sump is done by a sump pump, which is a __________ pump.

single stage vertical

A hydraulic ram acts as a/an __________ pump.

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

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). a. FL-2T, ML-1T-1 b. FLT, ML-1T-1 c. ML-1T-3, F-1L2T d. 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

displaced volume of the fluid.

The normal stress is the same in all directions at a point in a fluid, when the fluid is

having no motion of one fluid layer relative to the other.

The friction factor for turbulent flow in a hydraulically smooth pipe

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

What causes convective acceleration in fluid flow ?

Non-uniformity of flow

The Stoke's stream function applies to the

cases of axial symmetry.

Slugging in a fluidised bed can be avoided by using

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

The simple pitot tube measures the __________ pressure.

total

Capacity of a hydraulic accumulator is defined in terms of maximum

amount of energy stored.

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

mean velocity

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. a. Re << 1, accelerating flow b. Re >> 1, accelerating flow c. Re << 1, decelerating flow d. Re >>1, decelerating flow

Re >>1, decelerating flow

Manometers measure the __________ pressure.

difference in

Which of the following fluid forces are not considered in the Navier-Stoke's equation? a. Gravity forces b. Viscous forces c. Pressure forces d. Turbulent forces

Turbulent forces

Which of the following may be termed as a variable orifice flowmeter ?

Rotameter

In turbulent flow, a rough pipe has the same friction factor as a smooth pipe

when the roughness projections are much smaller than the thickness of the laminar film.

Air vessel provided in a reciprocating pump a. smoothens the flow by avoiding pulsations. b. increases the volumetric efficiency of the pump. c. saves the pump from the danger of cavitation. d. none of these.

none of these.

Bernoulli's equation is dependent on the a. first law of thermodynamics. b. third law of thermodynamics. c. law of conservation of momentum. d. none of these.

none of these.

The capacity of an accumulator is the maximum

energy which it can store.

With increase in the temperature, viscosity of a liquid

decreases

Vena-contracta pressure tapping is at a distance __________ from the position of an orificemeter fitted in a pipe of internal diameter 'd'

0.5 d

The pump impeller and the turbine runner in a hydraulic torque converter

have different diameters.

Reciprocating pumps compared to centrifugal pumps

are not subject to air binding.

The fluid property which matters for fall-ing rain drops to acquire spherical shape is its

surface tension

The simple pitot tube does not measure the a. static pressure. b. dynamic pressure. c. velocity at the stagnation point. d. all (a), (b) and (c).

all of these

Boundary layer separation occurs when the

cross-section of the channel is reduced.

The head loss in turbulent flow in a pipe varies

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

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

For the free settling of a spherical particle through a fluid, the slope of, CD-log NRe , plot is

-1

A centrifugal pump loses prime after starting. The reason of this trouble may be a. incomplete priming. b. too high a suction lift. c. low available NPSH and air leaks in the suction pipe. d. all (a), (b), and (c).

all of these

Venturimeter and orificemeter measures the __________ of the fluid.

average velocity

Surge tanks are provided in high pressure water pipelines to

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

Isotropic turbulence occurs

where there is no velocity gradient.

The co-efficient of drag and lift for an incompressible fluid depends on the

Reynolds number

Euler's equation of motion states, that at every point, the

force per unit mass equals acceleration.

Hydraulic intensifier is used for increasing the

intensity of pressure of the liquid.

In fluid flow, cavitation is caused, if the

flow pressure approaches its vapor pressure at the prevailing temperature.

Hydrometer measures the specific gravity of liquids based on the principles of buoyancy. Pycnometer is used to measure the specific gravity of a. powder & grannular solids b. liquids c. low melting point semi-solids d. all 'a', 'b' & 'c'

all of these

Euler's equation of motion is a statement expressing

conservation of mass.

During ageing of fluid carrying pipes, the

absolute roughness increases linearly with time.

Pick out the wrong statement. a. The form drag is dependent upon the occurrence of a wake. b. The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance. c. An ideal fluid is the one, which has negligible surface tension and obeys the Newton's law of viscosity. d. 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

steady and the cross-section is unchanged.

Very small pressure difference (< 5 mm water coloumn) can be most conveniently measured by a/an __________ manometer.

inclined tube water.

For pipe flows, head is proportional to __________ at constant capacity(where, D = pipe diameter).

1/D^5

The Navier-Stokes equation deals with the law of conservation of

momentum

A differential pressure cell is used for

remote recording of pressure difference.

If more than two branches of pipes are to be connected at the same point, then use a/an

tee

In case of a centrifugal pump, the ratio of total delivered pressure to pressure developed with the impeller is called the __________ efficiency.

manometric

Acceleration head in a reciprocating pump

does not change the work requirement of the pump.

The ratio of inertial forces to elastic forces is called the __________ number.

Mach

Fluid flow at increasing rate through a diverging pipe is an example of __________ flow.

non-steady non-uniform

The temperature in isentropic flow

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 compressible

Check in a centrifugal pump is a. provided in the discharge line. b. generally a globe valve. c. provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running. d. all (a), (b) and (c).

all of these

Drag force acting on a body does not depend upon the

density of the body.

Centrifugal pump is normally classified on the basis of the

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 wall

In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where, T = absolute temperature )

√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/16

Hydraulic intensifier is used for increasing the

intensity of pressure of the liquid.

In an incompressible fluid, the density is

not affected with moderate change in temperature & pressure.

Check valves are used

for unidirectional flow.

Velocity distribution for flow between two fixed parallel plates

varies parabolically across the section.

Priming is needed in a __________ pump.

centrifugal

Which of the fluid forces are not considered in the Reynold's equation of flow ? a. Viscous forces b. Turbulent forces c. Pressure forces d. Compressibility forces

Compressibility forces

For ideally incompressible fluid, the Mach number will be

A mono pump is a __________ pump.

positive acting rotary

Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of __________ flow type.

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

Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller. a. radius of b. speed of c. fluid velocity leaving d. 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

Boundary layer separation is caused by the

adverse pressure gradient.

With increase in temperature, the vapor pressure of liquids

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.

The ratio of wall drag to total drag in the Stoke's law range is

2/3

Rotary vacuum pumps can reduce the absolute pressure to as low as __________ mm Hg.

0.01

A pitched-blade turbine draws __________ a straight blade turbine.

less power than

The most suitable flow measuring device for the fluid flow measurement in a very large diameter pipeline is a

pitot tube

A centrifugal pump is called a turbine pump, if it is having a

vaned diffusion casing.

Remote control valve is a __________ valve.

butterfly

Which of the following quantities are computed by using the hydraulic radius for non-circular ducts ? a. Velocity and relative roughness. b. Head loss and velocity. c. Reynold number, relative roughness and head loss. d. Reynolds number and friction factor.

Reynold number, relative roughness and head loss.

Centre of pressure in an immersed body is __________ the centre of gravity.

below

The centre of pressure is

a point on the line of action of the resultant force.

Pascal law is not applicable for a/an __________ fluid. a. accelerating frictionless b. static c. uniformly moving d. none of these

none of these

In a fluidised bed reactor

temperature is more or less uniform.

The flow of a liquid through tapering pipe at a constant rate is an example of __________ flow.

steady non uniform

Pick out the correct statement pertaining to transition/ entrance length in fluid flow. a. 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. b. Transition length for laminar flow of Newtonion fluids in a pipe of diameter 'd' is equal to 0.05. D.NRe. c. Transition length for turbulent flow of Newtonion fluids in a smooth pipe of diameter 'd' is equal to 50 D. d. all (a), (b) and (c).

all of these

A perfect gas

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.

pitot tube

For a given Reynold number as d/D for an orifice increases, Cd will (where, d & D are orifice & pipe diameters respectively).

increase

Speed of sound in an ideal gas depends on its

temperature

A centrifugal pump designed for handling water (μ = 1 cp) will deliver __________ when pumping a thicker oil (μ = 30 cp).

less head & capacity

If 'x' is the depth of flow in an open channel of large width, then the hydraulic radius is equal to

In fluid flow, the boundary layer separation can not occur a. in case of boundaries experiencing form drag. b. at points of abrupt changes in the flow directions. c. in laminar flow. d. none of these.

none of these.

For a given fluid flow rate, which of the following incurs maximum head loss ?

Orifice meter

Which of the following assumptions enables the Euler's equation of motion to be integrated ? a. The fluid is incompressible. b. The fluid is non-viscous. c. The continuity equation is satisfied. d. The flow is rotational and incompressible.

The fluid is incompressible.

A fluid whose apparent viscosity increases with shear rate is termed as the __________ fluid.

dilatant

Which of the following is the most common pump for pumping either raw sewage or sludge ?

Reciprocating pump

Transition length for a turbulent fluid entering into a pipe is around __________ times the pipe diameter.

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

Reciprocating pumps are not able to compete with the centrifugal pump for industrial use, mainly because these pumps have

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

Which of the following pipe bends will incur the largest head loss ?

U-bend

Which is the most efficient and best for measuring very small flow rate of gases ?

Rotameter

When the water is warm, the height to which it can be lifted by a pump

decreases due to reduced vapour pressure.

Pipes having diameter 14 inches or more are designated by their

outside diameter

Viscosity of water at 40°C lies in the range of

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

The dimension of kinematic viscosity is

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

10 m/sec

Turbulent flow generally occurs for cases involving a. highly viscous fluid b. very narrow passages c. very slow motion d. none of these

none of these

Lower BWG means __________ of the tube.

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.

parabolic

The Prandtl mixing length is

useful for computing laminar flow problems.

N^2Re/NFr is called the __________ number.

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

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 << 1

increases linearly with V.

Self-priming centrifugal pump can be used for a. booster service. b. pumping liquid fertilisers (e.g. liquid NH3). c. pumping industrial wastes. d. all (a), (b) and (c).

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 a. pipe length b. fluid velocity in the pipe c. time taken to close the valve d. all (a), (b) and (c)

all of these

Bernoull's equation does not apply to the functioning of a/an a. venturimeter b. orificem c. pitot tube d. 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'?

8 . Vavg/D

Pascal's law is valid, only when the fluid is

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.

11 m

The pressure head of a flow meter remains constant for

rotameter

A venturimeter can not be used for the direct measurement of a. datum difference in the stretch of pipeflow b. pressure difference in the flow throughpipeline. c. friction loss in pipe flow. d. all (a), (b) and (c).

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

discharge

Which of the following is used for very accurate measurement of flow of gas at low velocity ?

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

A pressure of 10 m head of water is equivalent to __________ kN/m2.

A pressure head of 320 metres of water in meters of CCl4 (sp.gr = 1.6) will be

200

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

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

Maintenance cost of a __________ pump for a particular duty is the least.

centrifugal

Choking in case of pipe flow means that a

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.

electrical conductivity

The nominal size of a hose pipe is specified by its

I.D.

Transition from laminar flow to turbulent flow is aided by the a. surface roughness and curvature (i.e.sharp corners). b. vibration. c. pressure gradient and the compressibility of the flowing medium. d. all (a), (b) & (c).

all of these.

For flow of fluids through packed bed, the superficial velocity is

less than the average velocity through channels.

Cd is always __________ Cc.

greater than

Buoyant force

depends on the weight of the floating body.

Which of the following is an undesirable property of a manometric liquid ?

High vapour pressure.

Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head.

manometric

The speed of sound in an ideal gas varies as the

temperature

The maximum head that can be developed by a single impeller is __________ ft.

250-300

The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is

< 1

The general relationship between speed N, head H, power P and discharge Q for a centrifugal pump is

Q∝N : H∝N^2 : P∝N^3

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 ?

Foot valve provided in the pump is a __________ valve.

back pressure

The discharge co-efficient for an orificemeter does not depend upon the

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? a. Increasing the impeller speed and the volute area. b. Increasing the number of vanes in the impeller. c. Mounting of two or more impellers in series on a single shaft. d. 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

Path followed by water jet issuing from the bottom of a water tank will be a

parabola (vertex being at the opening).

Which of the following produces maximum pressure difference for transportation of gases ?

Compressors

Drag co-efficient in hindered settling is __________ that in free settling.

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.

66.6

One dimensional fluid flow implies the

flow in which transverse components are zero.

__________ forces act on a particle moving through a stationary fluid. a. Gravity b. Drag c. Buoyant d. all (a), (b), & (c)

all of these

Hydraulic radius is the ratio of

flow area to wetted perimeter.

The unit of bulk modulus of elasticity for a liquid in S.I. unit is

N/m^2

Power requirement of fans having constant wheel diameter varies __________ fan speed.

as cube of

In the low Reynolds number region, the drag force on a sphere is proportional to

The continuity equation

represents the conservation of mass.

Experimental study of laminar fluid flow through a circular tube was conducted by

Hagen and Poiseuille

The most economical flow control valve for use with large diameter pipes is a

butterfly valve

Each term in Bernaulli's equation represents the __________ of the fluid.

energy per unit weight

Which of the following is a dimensionless parameter ? a. Angular velocity b. Specific weight c. Kinematic viscosity d. None of these

None of these

If the head over the triangular notch is doubled, the discharge will increase by __________ times.

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.

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^4

Interstage coolers are provided in a multistage compressor to

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. a. NPSH required. b. BHP required by the pump. c. head of the liquid pumped. d. all (a), (b) and (c).

all of these

Reynolds number is the ratio of

inertial forces to viscous forces.

The discharge through a venturimeter depends upon

pressure drop only.

N. second/m^2 is

the S.I. unit of dynamic viscosity.

The distance between metacentre and __________ is called metacentric height.

centre of gravity

Check valve is used for __________ flow.

unidirectional

Capacity of a rotary gear pump can be varied by a. changing the speed of rotation. b. bleeding air into suction. c. bypassing liquid from the suction or discharge line. d. all (a), (6) and (c).

all (a), (6) and (c).

For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor.

brings about no further reduction of

Power number is the ratio of

drag stress to inertial stress.

The momentum correction factor for the velocity distribution of laminar flow is a. 1.3 b. 1.66 c. 2.5 d. none of these

none of these

For the same flow rate of a fluid, the pressure drop is the least for

venturimeter

The valve commonly used in pipes larger than 2" dia is a

gate valve

Foot valves are provided in the suction line of a centrifugal pump to

avoid priming, every time we start the pump.

An ideal fluid is

frictionless & incompressible.

In area meter (e.g., rotameter), with increase in the fluid flow rate, the

pressure drop is almost constant.

The buoyant force acting on a floating body is dependent on the

weight of the liquid displaced.

In case of end to end connection of two or more pipes in series, the __________ each pipe.

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 ?

Blake-Pllummer equation

The flow of gas along a pipe in the direction of decreasing pressure causes decrease in its

specific volume

Centrifugal pump can't be used to pump a. molten sodium (used as a coolant in Fast Breeder Reactor). b. moderately viscous vegetable oil used in soap industry. c. thick molten soap at 80°C. d. none of the above.

thick molten soap at 80°C.

A stream line is

fixed in space in steady flow.

Quicksand is an example of a __________ fluid.

dilatent

Correction for capillary effect in manometers (used for pressure measurement) need not be applied, if diameter of the manometer tube is __________ mm.

> 12.5

Differential manometer measures the

pressure difference

The pressure and power requirement of a gas fan at constant speed & capacity varies __________ the gas density.

directly as

Boundary layer thickness in laminar flow over a flat plate increases as(where, d = distance from the leading edge.)

√d

Gradually varied flow in open channel is a/an __________ flow.

steady non-uniform

The line of action of the buoyant force acts through the

centroid of the displaced volume of fluid.

Cavitation in a centrifugal pump can be avoided by keeping the

inlet pressure high

Vane anemometer

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.

12.4

Laminar flow is characterised by the nonexistence of a. pressure fluctuation. b. eddies. c. deviating velocities. d. 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.

transition

Select the correct practical example of steady non-uniform flow. a. Motion of water around a ship in a lake. b. Motion of river around bridge piers. c. Steadily decreasing flow through a reducing section. d. 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.

four

Terminal velocity is

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

For an incompressible fluid, the bulk modulus of elasticity is

∞ N/m^2

A fluid is a substance, that

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

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.

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

Boundary layer exists in flow

of real fluids.

Rubber latex is an example of __________ fluid.

pseudoplastic

The frictional resistance in laminar flow does not depend on the

area of surface in contact.

A venturimeter measures the a. velocity head b. pressure c. point velocity d. none of these

none of these

Gradually varying fluid flow is an example of __________ flow.

non-steady uniform

Drag is the force component exerted on an immersed object,

the component being parallel to theflow direction.

To handle smaller quantity of fluid at higher discharge pressure, use a __________ pump.

reciprocating

Cocks are used to control

any liquid

The dimension of surface tension is

MT^-2

Pick out the correct statement. a. Fanning friction factor is inversely proportional to Reynolds number always. b. 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. c. Mach number in an incompressible fluid is always unity. d. 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 a. always inversely proportional to the Reynolds number. b. not dimensionless. c. not dependent on the roughness of the pipe. d. none of these.

none of these.

Rubber latex is an example of a __________ .fluid.

pseudoplastic

Which of the following factors does not contribute to the pressure drop in a pipeline ? a. Velocity of fluid b. Size of pipe c. Length of pipe and number of bends d. 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

cavitation

Working of a __________ pump characterises mixed flow.

turbine

The rate of change of moment of momentum represents the __________ by the fluid.

torque applied

Cd for the orifice plate varies from

0.58 to 0.8

The discharge through a V-notch weir varies as

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

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.

In case of venturimeters, friction losses are about __________ percent of maximum velocity head.

With increase in the schedule number of a pipe of a particular nominal size, the a. wall thickness also increases. b. I.D. of the pipe decreases. c. O.D. of the pipe remains constant. d. all (a), (b) and (c)

all of these

Turbine impeller

is effective over wide range of viscosities.

Friction produced by the formation of wakes is called the __________ friction.

form

Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency)

ηm = ηv . ηma

When the pipe Reynold's number is 6000, the flow is generally

turbulent

With a constant diameter impeller of a centrifugal pump

head varies as the square of speed.

For water, when the pressure increases, the viscosity

first decreases, and then increases

Location of vena-contracta in an orificemeter does not depend upon the

type of orifice.

At low Reynolds number

viscous forces control and inertial forces are unimportant.

For laminar flow through a closed conduit

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.

square root

Unsteady uniform flow is represented by flow through a/an

long pipe at decreasing rate.

If Blausius or Darcey friction factor is 'f1' then the Fanning friction factor is equal to

f1/4

Pick out the wrong statement pertaining to fluid flow. a. The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5. b. The Newtonion fluid velocity in a circular pipe flow is maximum at the centre of the pipe. c. Navier-Stokes equation is applicable to the analysis of viscous flows. d. 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

While starting a centrifugal pump, its delivery valve should be kept

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

Sewage sludge is an example of the __________ fluid.

Bingham plastic

Multistage centrifugal pumps are generally used for

high head.

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

0.766

A bed consists of particles of density 2000 kg/m^3. If the height of the bed is 1.5 metres and its porosity 0.6, the pressure drop required to fluidise the bed by air is

11.77 kPa

Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation ?

Develops high pressure

For a specific centrifugal air blower operating at constant speed & capacity, the power requirement and pressure vary

directly as gas density.

Capillary tube method of viscosity measurement is based on the

Hagen-Poiseulle's equation

It is possible to integrate an automatic flow controller to a

rotameter

For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is

less

For a reciprocating pump, the indicator diagram is the graph between the

volume swept by piston for one complete revolution and the pressure in the cylinder.

High specific speed of a pump implies that, it is a/an __________ pump.

axial flow

A gas (density = 1.5 kg/m^3 , viscosity = 2x 10^-5 kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5kg/m^3and viscosity of 3 x 10^-5kg/m.s flowing at 3 m/s will be

12600 Pa/m

One poise (unit of absolute/dynamic viscosity) is equivalent to one

gm/cm. sec.

The equation relating friction factor to Reynold number, f^-0.5 = 4 loge (NRe/f)^-0.4, is called the __________ equation.

Nikuradse

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

For an unstable equilibrium of a floating body (where, M = metacentre.)

M is below G

Which of the following can be used for the direct measurement of volumetric flow rate of slurry ?

Rotameter

A pipe is defined as 'hydraulically smooth', if the friction factor

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

28.2

Delivery of insufficient quantity of liquid by a pump may be caused by a. air leak in the inlet b. low rpm c. too high a lift d. all (a), (b) and (c)

all of these

In case of a __________ the energy of flow is considerably decreased downstream of the machine.

turbine

With increase in the shear rate, the apparent viscosity of pseudoplastic fluids

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

0.62

Purpose of hydraulic accumulator is to

generate high pressure to operate hydraulic machines like cranes, lifts, presses etc

Pick out the wrong statement. a. Surface tension of a liquid is because of the difference in magnitude of adhesive & cohesive forces. b. A hydrometer used for the determination of specific gravities of liquids works on the principle of buoyant forces. c. In case of unsteady fluid flow, the velocity at any given point does not change with time. d. 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.

Select the correct statement. a. The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter. b. 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. c. 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. d. 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.

In case of turbulent flow of fluid through a circular pipe, the

skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.

What is the maximum theoretical suction lift (metres) of a reciprocating pump ?

The terminal velocity of a particle moving through a fluid varies as dp^n. The value of n is equal to __________ in Stoke's law regime.

Function of air vessel provided in a reciprocating pump is to

reduce discharge fluctuation.

The Prandtl pitot tube measures the

velocity at a point in the flow.

Pressure drop in packed bed for turbulent flow is given by the __________ equation.

Blake-Plummer

In the complete turbulence zone (in rough pipes), the

friction factor is independent of the relative roughness.

Which of the following has the minimum compressibility ? a. Water at room temperature b. Air at room temperature c. Oxygen at room temperature d. Nitrogen at room temperature

Water at room temperature

In case of centrifugal fan or blower, the gas capacity varies as

speed

Pick out the wrong statement. a. A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocity. b. Newton's law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution. c. Laminar flow of viscous liquids is involved in the lubrication of various types of bearings. d. 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. a. In a static mass of liquid, the pressure at a point is the same for all liquids. b. Pressure decreases exponentially with elevation in an isothermal atmosphere. c. Atmospheric pressure = absolute pressure-gage pressure. d. 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 near the wall and flat in the middle.

Mach number is the ratio of the speed of the

fluid to that of the sound.

A piezometer opening measures the __________ fluid pressure.

undisturbed

Drag force on the float of a rotameter is(where Q = flow rate of the )

constant

The unit of dynamic viscosity in SI unit is

kg/m . sec

Pressure drop (Δp) for a fluid flowing in turbulent flow through a pipe is a function of velocity (V) as

V^2

Dean number is concerned with the

fluid flow through helical pipes.

The equation given below is called the __________ . F^-0.5 = 4.07 loge (NRe√f)^-0.6

Von-Karman equation

Poise is converted into stoke by

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

Kinetic energy of fluid per unit weight represented by the velocity head is given by

v^2/2gc

At a constant speed of the centrifugal pump . it __________ the impeller diameter. a. capacity varies directly with b. head varies as the square of c. horsepower varies as the cube of d. all (a), (b) and (c)

all of these

The pressure co-efficient is the ratio of pressure forces to __________ forces.

viscous

Vena-contracta formed during flow of a liquid through an orificemeter has

minimum liquid cross-section.

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)

Horsepower increase of a centrifugal gas compressor without altering the volumetric flow rate will __________ the gas discharge pressure.

increase

In continuous fluidisation

solids are completely entrained.

Glass pipes can be joined by

bell and spigot joint

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

greater in 0.5 mm dia tube.

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

Weber number is the ratio of inertial force to __________ force.

surface tension

The curve of metacentre for a floating body __________ the curve of buoyancy.

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°

The range of a particular rotameter can be increased by

use of floats of different densities.

Which of the following is dimensionless ? a. Angular velocity b. Fanning friction factor c. Specific volume d. None of these

Fanning friction factor

A liquid is pumped at the rate of 600 litres using 1000 rpm. If the rpm is changed to 1100, the liquid pumped is __________ litres.

660

A compressor that takes suction at a pressure below atmospheric and discharge against atmospheric pressure is called a __________ pump.

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 10^3 VOM + 10.94 x 10^6 V^2OM (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 ?

0.7

Dimension of kinematic viscosity is

L^2 . T^-1

A streamline is a line in flow field,

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

closed

__________ forces do not act in case of fluid flow.

Tensile

Non-colloidal solution is an example of the __________ fluid.

Newtonion

Boundary layer separation is caused by the

adverse pressure gradient.

Identification of pipelines carrying different liquids and gases is done by the __________ of the pipe.

colour

Pick out the correct statement. a. Human blood is a Newtonion fluid. b. A Newtonion fluid obeys Newton's law of cooling. c. For a non-Newtonion fluid, a straight line passes through the origin in a plot between shear stress and shear gradient. d. Thin lubricating oil is an example of a non-Newtonion fluid.

A Newtonion fluid obeys Newton's law of cooling.

What is the unit of kinematic viscosity in SI unit ?

M^2/sec

Hydraulic __________ works on the principle of Pascal's law of transmission of fluid pressure.

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

The contraction co-efficient for Borda's mouthpiece (for frictionless fluid) is

0.5

Purpose of air lift pump is to

lift water from a well by using compressed air.

Pick out the correct statement pertaining to venturimeter. a. A venturimeter with a fixed pressure drop discharges more, when the flow is vertically downward, than when the flow is vertically upward. b. The co-efficient of contraction of a venturimeter is always unity. c. 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. d. none of these.

none of these.

For very low pressure and high discharge rate, the compressor used is a/an __________ compressor.

rotary

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.

gear

What is the speed of sound (m/sec) in ordinary water ?

1500

Two piping system are said to be equivalent, when the __________ are same.

fluid flow rate & friction loss

Potential function is applicable only for __________ flow.

irrotational

Which of the following exemplifies a three dimensional fluid flow ? a. Fluid flow at the inlet to a nozzle b. Fluid flow between parallel plates c. Viscous fluid flow between converging plates d. 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.

The head loss due to sudden contraction is proportional to

velocity head

Cavitation occurs in a centrifugal pump when the suction pressure is

less than the vapour pressure of the liquid at that temperature.

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

The capacity of a centrifugal pump Can be increased by increasing the a. impeller diameter or speed. b. number of pumps and joining them in series, c. number of pumps and joining them in parallel. d. all (a), (b) and (c).

all of these

Which law is followed by the velocity distribution in the turbulent boundary layer?

Logarithmic law

The losses in open channel flow generally vary as the

first power of the roughness.

Out of the following flow measuring devices, which one incurs the maximum installation cost as well as pressure loss ?

Venturimeter

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

Which of the following has the maximum compression ratio ? a. Blower b. Compressor c. Vacuum pump d. Fan

Vacuum pump

Scale up of agitator design requires

all geometrical, dynamic and kinematic similarity.

The actual velocity at vena-contracta for flow through an orifice from a reservoir is given by

Cv . √2gH

The head loss in turbulent flow in pipe is proportional to(where, V = velocity of fluid through the pipe)

V^2

Unsteady non-uniform flow is represented by flow through a/an

expanding tube at increasing rate.

Prandtl number is a measure of the

heat conduction to viscosity of a fluid.

A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpmHead = 8 metresFlow = 1000 litres/minutes.If its speed is halved, then the new head will be __________ metres.

In hindered settling, the particles are

near each other,

A globe valve is the most suitable for applications, in which

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.

Pitot tube

One stoke (unit of kinematic viscosity) is equivalent to

1 cm^2/second

Air vessel of a reciprocating pump is initially filled with

compressed air

The ratio of inertial forces to gravity forces is called the __________ number.

Froude

Power required by a centrifugal pump is proportional to (where, D = diameter, N = r.p.m)

N^3D^5

Equivalent length of a pipe fitting is

dependent on Reynolds number.

Buckingham-π theorem states that in any physical problem including 'n' quantities having 'm' diamensions, the quantities can be arranged into __________ independent dimensionless parameters.

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

Existence of boundary layer in fluid flow is because of the

fluid viscosity

In case of laminar flow of fluid through a circular pipe, the

surface of velocity distribution is a paraboloid of revolution, whose volume equals half the volume of circumscribing cylinder.

Which of the following facilitates close control of flow of fluids ? a. Gate valve b. Globe valve c. Butterfly valve d. Check valve

Globe valve

Stoke's equation is valid in the Reynolds number range

0.01 to 0.1

When a fluid flows over a solid surface, the

velocity gradient is zero at the solid surface.

Pick out the wrong statement about cavitation. a. Sudden reduction of pressure in a fluid flow system caused by flow separation, vortex formation or abrupt closing of valve leads to cavitation. b. Cavitation may be caused due to boiling of liquid by decreasing the pressure resulting in formation & collapse of vapor cavities. c. Cavitation begins at higher static pressure and lower velocity in larger diameter pipelines resulting in audible noise. d. 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.

4000

The velocity for subsonic flow in a pipeline

increases in the downstream direction.

Permanent pressure loss in a well designed venturimeter is about __________ percent of the venturi differential.

The ratio of pressure forces to inertial forces is called the __________ number.

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, B, E

Cavitation in a centrifugal pump results from

low barometric pressure

For turbulent flow of newtonion fluid in a circular cross-section pipe, the ratio of maximum to average fluid velocity is

Water is flowing at 1 m/sec through a pipe (of 10 cm I.D) with a right angle bend. The force in Newtons exerted on the bend by water is

5π/2

The time of oscillation of a floating body is a. longer, if metacentric height is increased. b. independent of the metacentric height. c. dependent on the buoyant forces only. d. none of these.

none of these.

What is the value of Fanning friction factor f ' for smooth pipe at NRe = 106 approximately ?

0.003

Air vessel provided in a reciprocating pump is for

making the friction in pipe uniform.

A hydraulic accumulator comprises of

a cylinder and a plunger.

Bernoulli's equation for steady, frictionless, continuous flow states that the __________ at all sections is same.

total energy

A tube is specified by its

thickness & outer diameter both

Prandtl mixing length is

zero at the pipe wall.

The hydraulic diameter of an annulus of inner and outer radii Ri and Ro respectively is

2(Ro-Ri)

Ratio of inertial forces to surface tension forces is called the __________ number.

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

1.84

The ratio of inertial forces to viscous forces is called the __________ number.

Reynold

Enamels and paints are generally __________ fluid.

pseudo-plastic

With the increase in depth, the hydrostatic pressure in an unaccelerated incompressible fluid (in a constant gravitational field)

increases linearly.

Flow measurement in an open channel is done by a/an

weir

Newton's law of viscosity relates the

shear stress and rate of angular deformation in a fluid.

The equivalent diameter for fluid flow through square cross section channel of side 'x', for pressure drop calculation purpose is given by

Hydraulic radius of 6" x 12" cross-section, is __________ inches.

Baffles in mixing tanks are provided to

reduce swirling and vortex formation.

Which of the following equations is valid for laminar flow of a fluid through packed bed? a. Fanning equation b. Kozney - Karman equation c. Hagen-Poiseuille equation d. Blake-Plummer equation

Kozney - Karman equation

Forces acting on a particle settling in fluid are __________ forces.

gravitational or centrifugal buoyant drag.

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.

In a dry packed bed, the pressure drop will be changed by increasing the flow rate as

V^1.8

Specific speed of a centrifugal pump depends upon the __________ head. a. suction b. delivery c. manometric d. none of these

none of these

Navier-Stokes equation is useful in the analysis of __________ fluid flow problems.

viscous

The maximum discharge through a circular channel takes place, when the depth of the fluid flow is __________ times the pipe diameter.

0.95

When the head pumped against is less than the head of the fluid used for pumping, the usual device is a/an

airlift

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

decrease

What is the value of co-efficient of discharge for square edged circular orifice (for β = 0.3 to 0.5) ?

0.61 - 0.63

A lubricant 100 times more viscous than water would have a viscosity (in Pa.s)

0.1

Nominal Pipe Size (NPS) of a pipe less than 12 inches in diameter indicates its

neither inner nor outer diameter

I.D. of 1/4" schedule 40 pipe is 0.364". I.D. of a 1/2" schedule 40 pipe would be __________ inch

0.5

Two liquids manometer is used for measuring small pressure differences in

gases

A piezometer provided in the pipe measures

static pressure

The pump used for irrigation purposes is generally designed for

large capacity & low head.

In centrifugal pumps, cavitation occurs, when pressure of the impeller eye or vane becomes

less than liquid vapor pressure.

Pressure gradient in the pipe flow is influenced by the a. diameter of pipe. b. velocity of the fluid. c. density & viscosity of the fluid. d. all (a), (b) and (c).

all of these

__________ pump is the most suitable device for discharging a liquid against a pressure of ≥ 1500 kgf/cm2.

Plunger

Boiler feed water pump is usually a __________ pump.

multistage centrifugal

Viscosity of a liquid decreases __________ with rise in temperature.

logarithmically

In case of a pipe of constant cross-sectional area, the maximum fluid velocity obtainable is

the velocity of sound.

Discharge in laminar flow through a pipe varies

as the square of the radius.

The lift of a ballon is

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 ? a. Stream line body b. Two dimensional body c. Bluff body d. None of these

Bluff body

Major loss in sudden contraction in pipe flow is due to

flow contraction.

Which of the following can be used to create a flow of gas, where no significant compression is required ?

Blower

The ratio of actual discharge to theoretical discharge through an orifice is equal to

Cc . Cv

A free jet of water of cross-sectional area 0.01m^2 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

4000 N

Cp/Cv is termed as

adiabatic constant

Which of the following is a Newtonian fluid? a. Rubber latex b. Sewage sludge c. Quicksand d. Non-colloidal solution

Non-colloidal solution

Which of the following valves will incur maximum pressure drop for the same discharge of water ? a. Globe valve b. Gate valve c. Needle valve d. Butterfly valve

Needle valve

Pressure drop in a fluidised bed reactor is __________ that in a similar packed bed reactor.

more than

In deriving Bernoulli's equation, fluid is assumed to be

incompressible, frictionless, steady, along a streamline.

Unit of mass velocity is

kg/m^2. hr

With increase in molecular weight of the gas, the head developed by a centrifugal compressor will

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).

12.6 H

The boundary layer thickness at a given section along a flat plate __________ with increasing Reynold's number.

decreases

Low specific speed of a pump implies that, it is a/an __________ pump.

centrifugal

For pumping slurry, one can use a __________ pump.

diaphargm

Bernoulli's equation describes the

mechanical energy balance in potential flow.

Which law/principle of solid mechanics is similar/equivalent to Newton's law of viscosity in fluid mechanics ?

Hooke's law.

When larger particles e.g., grains are subjected to fluidisation, the corresponding bed produced is termed as the __________ bed.

spouted

Minimum fluidisation velocity for a specific system depends upon the a. particle size. b. fluid viscosity. c. density of both the particle & the fluid. d. all (a), (b) and (c).

all of these

Potential flow is characterised by the

irrotational and frictionless flow.

For the production of very high vacuum, a __________ pump is normally used.

diffusion

In parallel pipe problems, the

head loss is the same through each pipe.

Fluid flow through a packed bed is represented by the __________ equation.

Ergun's

__________ is an example of axial flow impeller.

Propeller

Froude number is not a factor

when there is no vortex formation.

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

Horsepower requirement for given pump capacity depends upon the a. specific gravity of the liquid b. suction lift c. discharge head d. all (a), (b) and (c)

all of these

Bernoulli's equation accounts for the

different forms of mechanical energy

__________ pumps are a group of vacuum pumps.

Hyter

Plunger pumps are used for

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

In turbulent flow, the

shear stresses are generally larger than in a similar laminar flow.

Momentum correction factor used in fluid flow problems accounts for the

non uniform direction of velocities at inlet & outlet sections.

Design of the casing of centrifugal pump should be such as to minimise the

loss of kinetic head

Which of the following is used for pumping crude oil from oil well ? a. Single stage centrifugal pump b. Gear pump c. Screw pump d. 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

sudden expansion of flow in the downstream occurs.

__________ flow means the flow of incompressible fluid with no shear.

Potential

The continuity equation

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 square of

Pressure drop in a packed bed for laminar flow is given by the __________ equation.

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.

pseudoplastic

Stoke's law is valid, when NRe, p is less than

Froude number is the ratio of

inertial stress to gravitational stress.

Normal depth in open channel flow is the depth of flow in the channel

corresponding to uniform flow.

Which of the following flow measuring devices is an area meter ? a. Venturimeter b. Orifice meter c. Anemometer d. Rotameter

Rotameter

With decrease in particle size to be fluidised by a particular fluid, the operating range of fluidisation velocity

does not change

Diaphragm valves are used for handling __________ fluids.

corrosive

The schedule number of a pipe is an indication of its

wall thickness

Minimum porosity for fluidisation is

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

decrease

Steady non-uniform flow is exemplified by flow through a/an

expanding tube at constant rate.

The maximum depth from which a centrifugal pump can draw water is

34 feet.

Hot wire anemometer is used to measure the

velocity of gases.

Propeller type centrifugal pumps are most suitable for

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

Momentum transfer in laminar flow of fluids results due to the

velocity gradient

The capillary rise of mercury is maximum in glass tube of dia __________ mm.

0.5

Diaphragm pumps are used to transport

slurries

For steady ideal fluid flow, the Bernoulli's equation states that the

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. a. speed of b. diameter of c. fluid velocity leaving d. all (a), (b) and (c)

all of these

A hydraulic press has a ram of 10 cms in diameter and a plunger of 1 cm in diameter. The force required on the plunger to raise a weight of 10 tons on the ram is __________ kg.

100

Choose the set of pressure intensities that are equivalent. a. 4.33 psi, 10 ft. of water, 8.83 inches of Hg. b. 4.33 psi, 10 ft. of water, 20.7 inches of Hg. c. 10 psi, 19.7 ft. of water, 23.3 inches of Hg. d. 10 psi, 19.7 ft. of water, 5.3 inches of Hg.

4.33 psi, 10 ft. of water, 8.83 inches of Hg.

Pick out the wrong statement about a streamline. a. It is always parallel to the main direction of the fluid flow. b. It is a line across which there is no flow and it is equivalent to a rigid boundary. c. Streamlines intersect at isolated point of zero velocity and infintie velocity. d. 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

most of the pressure drop is not recoverable.

The discharge through a rectangular weir varies as

H^3/2

In case of supersonic flow of a fluid through pipeline, the 'Mach number' is

> 1

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 power consumed now will be __________ hp.

0.5

Transition length for turbulent flow in smooth pipe is equal to __________ times the pipe diameter.

Disc compensators are provided in large diameter fuel gas carrying pipelines to

account for contraction/expansion of pipe due to temperature changes of the surroundings.

Discharge from a 24 inch pipe of water at 10 ft/sec will be __________ ft3/sec.

125.6

Paper pulp is an example of __________ fluid.

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

0.95

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. (1)

ρL . A.Hg

A relief valve

is a directional control valve.

An isentropic process is the one, in which

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 both laminar & turbulent flow.

For motion of spherical particles in a stationary fluid, the drag co-efficient in hindered settling compared to that in free settling is

Specific speed of a centrifugal pump relates it with another pump having the

dynamic similarity

Air vessel fitted to a reciprocating pump

decreases the work done.

Deformation drag, which is caused by widespread deformation of fluid around the immersed body

occurs when NRe is very small.

In isotropic turbulence, the __________ are equal to each other.

mean square of velocity fluctuations in the three co-ordinate directions

Viscosity of water is about __________ times that of air at room temperature.

Net positive suction head (NPSH) of a centrifugal pump must be

greater than the vapour pressure of the liquid.

Actual lift of a pump is always less than the theoretical lift and is limited by the a. specific gravity & temperature of the liquid. b. leakage & pressure decreasing at higher elevations. c. frictional resistance through pipes, fittings & passages. d. all (a), (b) and (c).

all of these

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?

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

unsteady

The __________ pressure is measured by a static tube.

static

The speed of a sound wave in a gas is analogous to the speed of

an elementary wave in an open channel.

Mercury is an ideal barometric fluid mainly due to its

very low vapor pressure.

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 ?

Drag, gravitational and buoyancy forces are impportant.

A gas

is a supercritical vapor.

Pitot tube measures the __________ of a fluid.

point velocity

Which of the following is not dimension-less? a. Froude number b. Kinematic viscosity c. Pressure co-efficient d. None of these

Kinematic viscosity

In laminar flow through a round tube, the discharge varies

inversely as the viscosity.

Which is not a variable head meter ? a. Venturimeter b. Pitot tube c. Rotameter d. None of these

Rotameter

The pipe wall thickness is minimum for a pipe of given nominal size having schedule number

Reynolds number for flow of water at room temperature through 2 cm dia pipe at an average velocity of 5 cm/sec is around

1000

Centrifugal pumps as compared to reciprocating pumps

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 ?

Angular deformation

In which type of fluid flow, the velocity of flow of fluid changes from point to point in the fluid at any instant ?

Non-uniform

The continuity equation in ideal fluid flow states that

net rate of inflow into any small volume must be zero.

Bernoulli's equation is not applicable, when the flow is a. irrotational. b. incompressible. c. viscous. d. all (a), (b) & (c).

all of these.

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)

Centre of pressure of a plane surface of arbitrary shape immersed vertically in a static mass of fluid

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.

average drag per unit projected area

Creeping flow around a sphere is defined, when particle Reynolds number is

< 0.1

Open channel liquid flow is most conveniently measured by a

notch

Toothpaste is a

dilatent

Slurries can be most conveniently pumped by a __________ pump.

centrifugal

Volute type of casing is provided in a centrifugal pump to

increase the discharge.

In a free vortex, the

velocity changes linearly with radial distance.

Pick out the wrong statement. a. The eddy viscosity is a function of the type of turbulence involved. b. The eddy viscosity is a fluid property. c. The viscosity of gas increases with increase in temperature. d. 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

parabolic

In fluid flow, the stagnation point is defined as a point, where the __________ is zero.

flow velocity

A special type of liquid transporting device is the diffuser pump, in which __________ are minimised.

shock losses

Which of the following is most prone to pulsating discharge flow ?

Gear pump

A streamline is

drawn normal to the velocity vector at every point.

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

Drag is defined as the force exerted by the

fluid on the solid in the direction of flow.

The boundary layer is that part of a moving fluid, in which the fluid velocity is

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 a. inverse of fluid viscosity. b. square of particle size. c. difference in the densities of the particle & fluid. d. all (a), (b) and (c).

all of these

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

Nominal size of a pipe is an indication of its __________ diameter.

approximate

Fluidised beds are formed, when the

gravity force is less than the fluid friction.

A fluid is pumped at the rate of 10 lb/sec to a height of 55 ft. The horse power required is __________ hp.

Pick out the wrong statement: a. The vacuum pressure is always the negative gauge pressure. b. The pressure of the liquid measured by a piezometer tube is the gauge pressure. c. Manometric liquid should have high surface tension. d. 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.

Medium viscosity lubricating oil can be most ideally pumped by a __________ pump.

vane

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^2.5

Pump used for the transportation of molten sodium in a fast breader reactor is a/an __________ pump.

electromagnetic

Small pressure differences in liquids is measured using a/an

inclined tube manometer.

With increase in pump speed, its NPSH requirement

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.

inversely proportional to

Gear pump

is a positive displacement pump.

Most of the centrifugal pumps used in chemical plants are usually __________ driven.

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.

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

hot wire anemometer

The time taken for gravity flow of a fixed volume of liquid (as in Redwood viscometer) is directly proportional to its

ratio of absolute viscosity to density.

Sewage sludge is __________ type of non-Newtonion fluid.

Bingham plastic

Ratio of pressure and inertia force gives __________ number.

Euler

Permanent loss in a venturimeter is about __________ percent of the pressure drop in theupstream cone.

10 .

Volume of liquid displaced by a floating body is equivalent to its

own weight

The __________ is measured by a piezometric opening.

total pressure

What is the pipe called which lifts water from a reservoir to a greater height than the initial level in the supply reservoir ?

Siphon

Steady uniform flow is represented by flow through a/an

long pipe at constant rate.

Pick out the correct statement pertaining to the flow through a converging-diverging tube. a. The value of Mach number is always unity at the throat. b. No shock wave develops in the tube when the Mach number at exit is greater than unity. c. Throughout the converging portion of the tube, the density increases in the downstream direction. d. 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

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

Steady flow occurs, when the

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

decreases

Which of the following two quantities when same, makes one pipe system equivalent to another pipe system ? a. Head & discharge b. Length & discharge c. Length & diameter d. Friction factor & diameter.

Head & discharge

The kinetic energy correction factor for velocity distribution of laminar flow is

1.66

Priming of a centrifugal pump is done to

avoid chances of separation inside the impeller.

Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 200 kg/m3, Dp = 0.05 cm) of 60 cm bed depth and bed porosity of 0.5 expressed in cm of water (manometer) is

For pipes that must be broken at intervals for maintenance, the connector used should be a/an

union

A fluid is the one, which

cannot remain at rest under the action of shear force.

Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, σ = surface tension of mercury)

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

2Δp

Fluid flow in a/an __________ is an example of pressure flow.

pipe

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^-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

269

A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m^3 ) is to be fluidised by water (density 1000 kg/m^3 ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is

4.4 KPa

Select the wrong statement pertaining to flow of an incompressible fluid through a venturimeter. a. For frictionless flow, the fluid pressure entering the venturi meter will be exactly equal to that leaving the venturimeter. b. Discharge of fluid through a venturimeter depends upon the gage difference irrespective of the orientation of venturimeter. c. Venturimeter occupies less space than an orificemeter. d. 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

The bulk modulus of elasticity of a liquid

increases with pressure.

Curve III in the above diagram represents a/an

pseudo plastic fluid

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)?

The line traced by a single fluid particle as it moves over a period of time is called __________ line.

path

A stream tube is that, which has __________ cross-section entirely bounded by stream lines.

any convenient

The unit of velocity head is

ft-lbf/lb

Which of the following properties of a fluid is responsible for offering resistance to shear ? a. Surface tension. b. Viscosity. c. Specific gravity. d. All (a), (b), and (c).

Viscosity.

Erosion and pits formation on the impeller of a centrifugal pump may be due to

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.

parabola

The excess of the sum of pressure & velocity heads over the vapor pressure of the liquid at the suction is called the

net positive suction head (NPSH).

Piezometric head is the sum of the __________ heads.

elevation & pressure

Propellers are

axial flow mixers.

Which of the following is not an advantage of fluidisation from transfer operation point of view? a. Intimate contact of the fluid with all parts of the solid particles. b. Lower fluid pumping power requirement. c. Minimisation of temperature variation. d. Prevention of particle seggregation.

Lower fluid pumping power requirement.

Upto what value of 'Mach number', a fluid may be considered as incompressible ?

0.3

The head developed by a centrifugal pump is largely determined by the

angle of the vanes and the speed of the tip of the impeller.

Pick out the wrong statement: a. Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer. b. Blowers develop a maximum pressure of 2 atmospheres. c. Friction losses in pipe fittings are generally expressed in terms of velocity heads. d. Fanning friction factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number.

Friction losses in pipe fittings are generally expressed in terms of velocity heads.

Flow rate of high velocity flue gas discharged through a stack to the atmosphere can be most conveniently measured by a

pitot tube

Potential flow is the flow of

incompressible fluids with no shear.

The value of critical Reynolds number for pipe flow is

1300

Mach number is important in a fluid flow problem, when the inertia and __________ forces predominate.

elastic

Fanning friction factor is equal to(where, fB = Blassius friction factor).

fB/4

In case of coutte flow, the fluid flow is between two large flat parallel plates with

top plate moving and the bottom plate fixed.

In a stabilised soap bubble, pressure inside it compared to external pressure is

The component of acceleration resulting due to unsteady nature of flow is called __________ acceleration.

local

Power required for mixing Newtonion fluids is a function of the a. speed of impeller, diameter of impeller & viscosity. b. density & viscosity of fluid only. c. density of fluid, viscosity of fluid & impeller dia only. d. none of these.

none of these.

Multistage compressors are used in industry, because they

resemble closely to isothermal compression.

The hydrodynamic and thermal boundary layers will merge, when

Prandtl number is one.

Differential manometer measures the

pressure difference between two points.

For a stable equilibrium of a submerged body (where, G and B are centres of gravity & buoyancy respectively).

B is above G

With increase in the ratio of orifice diameter to pipe diameter in case of an orificemeter, the overall pressure loss

remains constant

The vent valve provided in a liquid handling centrifugal pump is a. generally a needle valve. b. used to release any gases that might be vapour locking the pump. c. helpful in easy removal of samples. d. all (a), and (b) and (c).

all (a), and (b) and (c).

The discharge through a semi-circular weir varies as (where, H = Head of liquid.)

H^2

The Mach number for hypersonic flow of compressible fluid is

> 4

Boundary layer thickness in turbulent flow over a flat plate increases as(where, d = distance from the leading edge.)

d^4/5

The valve used for very remote and accurate control of fluid is a __________ valve.

needle

f = 16/NRe, is valid for a. turbulent flow b. laminar flow through an open channel c. steady flow d. none of these

none of these

A mixed flow centrifugal pump

employs such an impeller, through which the flow is a combination of radial & axial flow.

In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure __________ the vapor pressure of the liquid at the suction temperature.

higher than

A rectangular surface 3' x 4', has the lower 3 edge horizontal and 6' below a free oil surface (sp. gr. 0.8). The surface inclination is 300 with the horizontal. The force on one side of the surface is(where, y = specific weight of water)

48y

16 mm/s

One dimensional flow implies

a flow which does not account for changes in transverse direction.

In case of turbulent flow of a Newtonion fluid in a straight pipe, the maximum velocity is equal to (where, Vavg = average fluid velocity)

1.2 Vavg

Centrifugal compressors compared to reciprocating compressors a. require less space. b. have quieter operation. c. have lower operating costs. d. all (a), (b) and (c).

all of these

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 )

1/μ

Umf is the minimum fluidisation velocity for a bed of particles. An increase in the superficial gas velocity from 2 Umf to 2.5 Umf results in (all velocities are smaller than the entrainment velocity of the particles) no change in the

bed height

Stoke's law is valid, when the particle Reynolds number is

< 1

Which of the following is not a dimension-less parameter ? a. Pressure-co-efficient b. Froude number c. Kinematic viscosity d. Weber number

Kinematic viscosity

In which of the following cases, it is possible for flow to occur from low pressure to high pressure ? a. Flow of liquid upward in a vertical pipe. b. Flow through a converging section. c. Flow of air downward in a pipe. d. Impossible in a constant cross-section conduit.

Flow through a converging section.

The blades of a centrifugal impeller are said to be curved forward, if the __________ of the motion of impeller blades.

outlet tip of a blade is towards the direction

For the same terminal conditions and fitting size, the least friction loss is incurred in a/an

union

A floating/submerged body is always stable, if its centre of gravity

lies below its centre of buoyancy.

Critical velocity in a pipe flow

increases as pipe diameter increases.

A centrifugal pump designed to pump water is employed to pump a more viscous oil. In the later case, the pump a. develops a lower head. b. capacity is reduced. c. requires more power. d. all (a), (b) and (c).

all of these

In an incompressible flow of fluid, the fluid

density does not change with pressure & temperature.

The ratio of maximum to average velocity in case of streamline flow between parallel plates is

1.5

A weir is used to measure the large water discharge rate from a river or from an open channel. A weir is not of __________ shape.

circular

Pressure co-efficient is the ratio of pressure forces to __________ forces.

inertial

Which of the following conditions must be satisfied for lift force to be developed ? a. The body should be bluff body. b. The body should be stream lined. c. Circulation around the body is essentially required. d. The main stream velocity must approach the velocity of sound in that fluid medium.

Circulation around the body is essentially required.

The Reynolds number for an ideal fluid flow is

∞

In case of a rotameter, the density of the float material is __________ that of the liquid it replaces.

more than

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

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

What is the maximum theoretical suction lift (metres) of a reciprocating pump ?

For an ideal fluid flow, Reynolds number is

∞

The exit cone angle in case of a standard venturimeter is __________ the entrance cone angle.

smaller than

A fluid is the one, which

cannot remain at rest under the action of shear force.

A fluid is the one, which

cannot remain at rest under the action of shear force.

One horsepower is equal to

550 lbf.ft/second

The pressure head on sudden contraction in a horizontal pipe is converted into the __________ head.

velocity

The pressure head on sudden contraction in a horizontal pipe is converted into the __________ head.

velocity

The continuity equation of fluid mechanics utilises the principle of conservation of

mass