Fluid Mechanics for Chemical Quiz 3

1 / 50

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

Decrease in effect

Increase in thrust

Develops noise

Develops high pressure

2 / 50

Centre of pressure in an immersed body is _______ the centre of gravity?

Below

Above

Either above or below; depends on the liquid density

3 / 50

Cd is always _______ Cc?

Less than

Equal to

Greater than

Either more or less than

4 / 50

Buckingham-? theorem states that in any physical problem including ?n? quantities having ?m? dimensions, the quantities can be arranged into ______ independent dimensionless parameters?

n/m

n-m

5 / 50

Check valve is used for _________ flow?

None of these

Unidirectional

Multidirectional

Very precise control of

6 / 50

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?

Head of the liquid pumped

BHP required by the pump

All A., B. and C.

NPSH required

7 / 50

Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement ?

f1 = f2

f1 > f2

Data not sufficient to relate f1 & f2

f1 < f2

8 / 50

Choose the set of pressure intensities that are equivalent ?

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

4.33 psi, 10 ft. of water, 20.7 inches of Hg

10 psi, 19.7 ft. of water, 5.3 inches of Hg

10 psi, 19.7 ft. of water, 23.3 inches of Hg

9 / 50

Differential manometer measures the______?

Pressure difference between two points

None of these

Atmospheric pressure

Sub-atmospheric pressure

10 / 50

Colebrook equation for friction factor in turbulent flow is given by, f-0.5 = -4 loge [(?/D) + (1.26/NRe ?F). It reduces to Nikuradse equation for a value of (?/D) equal to ___________?

0.5

11 / 50

Curve III in the bellow diagram represents a/an_________?

Ideal plastic

None of these

Pseudo plastic fluid

Dilatent fluid

12 / 50

Check in a centrifugal pump is_________?

Provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running

Generally a globe valve

Provided in the discharge line

All A., B. and C.

13 / 50

Capacity of a rotary gear pump can be varied by___________?

Bleeding air into suction

Bypassing liquid from the suction or discharge line

Changing the speed of rotation

All A., B. and C.

14 / 50

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

Occurs when NRe is very small

Is independent of body length

Depends mainly on cross-sectional shape

Is primarily a friction drag

15 / 50

Capacity of a hydraulic accumulator is defined in terms of maximum_______?

Volume available in the cylinder

Rate of falling of ram

Amount of energy stored

Flow rate through accumulator

16 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Have quieter operation

All A., B. and C.

Require less space

Have lower operating costs

17 / 50

Cp/Cv is termed as___________?

Weber number

Adiabatic constant

Mach number

Prandtl number

18 / 50

Critical velocity in a pipe flow__________?

Increases as fluid viscosity increases

Increases as pipe diameter increases

None of these

Independent of fluid density

19 / 50

Cocks are used to control _____?

Water

None of these

Any liquid

Solids

20 / 50

Cavitation occurs in a centrifugal pump when the suction pressure is_________?

Less than the vapour pressure of the liquid at that temperature

Greater than the vapour pressure of the liquid at that temperature

Equal to the vapour pressure

Equal to the developed head

21 / 50

Differential manometer measures the_____?

Pressure difference

Gauge pressure

Absolute pressure

Pressure gradient

22 / 50

Cd for the orifice plate varies from _____?

0.2 to 0.3

0.93 to 0.98

0.58 to 0.8

0.02 to 0.03

23 / 50

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

> 2.5

< 500

< 0.1

< 2100

24 / 50

Centrifugal pump can?t be used to pump _______?

Molten sodium (used as a coolant in Fast Breeder Reactor)

Thick molten soap at 80?C

Moderately viscous vegetable oil used in soap industry

None of the above

25 / 50

Check valve provided in the discharge line of a centrifugal pump serves the purpose of controlling the________?

Flow of liquid during operation of the pump

Back flow of fluid in the event of stoppage of pump

Discharge pressure

All A., B. and C.

26 / 50

Dean number is concerned with the______?

Fluid flow through helical pipes

Psychrometry

Fluid-particle interaction

Power consumption in agitated vessels

27 / 50

Check valves are used________?

At high pressure

In bends

For controlling water flow

For unidirectional flow

28 / 50

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

Is different for different fluids

Lies above the centroid of the plane surface

Is at the centroid of the plane surface

Is independent of the specific weight of the fluid

29 / 50

Buoyant force___________?

Depends on the weight of the floating body

Depends on the depth of the submergence of the floating body

None of these

For non-symmetrical bodies is not vertical

30 / 50

Dimension of kinematic viscosity is_______?

L2T-2

L2T

L2T-1

MLT-1

31 / 50

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

d4/5

d1/3

d2/3

32 / 50

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) ?

FLT, ML-1T-1

F-1L2T-1, MLT-3

ML-1T-3, F-1L2T

FL-2T, ML-1T-1

33 / 50

Centrifugal pump is normally classified on the basis of the_________?

Number of blades in impeller

Impeller blade angle

rpm

Type of casing

34 / 50

Cavitation in a centrifugal pump can be avoided by keeping the___________?

Outlet pressure low

Outlet pressure high

Inlet pressure low

Inlet pressure high

35 / 50

Disc compensators are provided in large diameter fuel gas carrying pipelines to__________?

Make the pipe joint leak-proof

Keep the pipe in proper orientation

Account for the pressure variation side the pipeline

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

36 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

Can be run with discharge line valve closed for a short interval

Do not need priming

Run at a lower speed for the same discharge

Deliver fluid with pulsating/fluctuating discharge

37 / 50

Boundary layer separation occurs when the______?

Pressure reaches a minimum

Cross-section of the channel is reduced

Valve is closed in a pipeline

Velocity of sound is reached

38 / 50

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

Loss of static head

None of these

Back flow through impeller

Loss of kinetic head

39 / 50

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

1/?

1/d

40 / 50

Brownian movement is prominent in the particle size range of ______ microns in case of settling of a particle in a fluid?

100 to 1000

2 to 3

0.01 to 0.10

200 to 300

41 / 50

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___________?

0.98

0.82

0.62

0.42

42 / 50

Cavitation can be prevented by_________?

Maintaining the suction head sufficiently greater than the vapour pressure

Maintaining suction head lower than the vapour pressure

Maintaining suction head = developed head

Suitably designing the pump

43 / 50

Choking in case of pipe flow means that a_____?

Specified mass flow rate cannot be achieved

Restriction in flow cross-section area occurs

Valve is closed in the line

None of these

44 / 50

Diaphragm pumps are used to transport__________?

Liquids

Slurries

Fluids

Solids

45 / 50

Capillary tube method of viscosity measurement is based on the _________?

Stoke?s law

None of these

Navier-stokes equation

Hagen-Poiseuille?s equation

46 / 50

Diaphragm valves are used for handling ________ fluids?

Viscous

Solid suspended

Corrosive

Non-Newtonian

47 / 50

Co-efficient of velocity is _____ the coefficient of discharge?

Equal to

More than

Less than

Not related to

48 / 50

Dimension of absolute viscosity is__________?

ML-1T

ML-1T-1

MLT

MLT-1

49 / 50

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

d1/3

d2/3

50 / 50

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

F-1. L

FL-1

F.L-2

F-2. L

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