Fluid Mechanics for Chemical Quiz 3

1 / 50

Check in a centrifugal pump is_________?

Provided in the discharge line

Generally a globe valve

All A., B. and C.

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

2 / 50

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

2 to 3

200 to 300

0.01 to 0.10

100 to 1000

3 / 50

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

Is at the centroid of the plane surface

Is different for different fluids

Lies above the centroid of the plane surface

4 / 50

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

Back flow through impeller

None of these

Loss of static head

Loss of kinetic head

5 / 50

Centrifugal pump is normally classified on the basis of the_________?

Number of blades in impeller

Type of casing

Impeller blade angle

rpm

6 / 50

Critical velocity in a pipe flow__________?

Independent of fluid density

None of these

Increases as fluid viscosity increases

Increases as pipe diameter increases

7 / 50

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

F-1. L

F-2. L

F.L-2

FL-1

8 / 50

Cocks are used to control _____?

Solids

Water

None of these

Any liquid

9 / 50

Capacity of a rotary gear pump can be varied by___________?

Changing the speed of rotation

All A., B. and C.

Bypassing liquid from the suction or discharge line

Bleeding air into suction

10 / 50

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

Rate of falling of ram

Amount of energy stored

Volume available in the cylinder

Flow rate through accumulator

11 / 50

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

Outlet pressure low

Outlet pressure high

Inlet pressure low

Inlet pressure high

12 / 50

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

Increase in thrust

Develops high pressure

Decrease in effect

Develops noise

13 / 50

Cd for the orifice plate varies from _____?

0.2 to 0.3

0.02 to 0.03

0.58 to 0.8

0.93 to 0.98

14 / 50

Choking in case of pipe flow means that a_____?

Restriction in flow cross-section area occurs

Valve is closed in the line

None of these

Specified mass flow rate cannot be achieved

15 / 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?

BHP required by the pump

Head of the liquid pumped

All A., B. and C.

NPSH required

16 / 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

Data not sufficient to relate f1 & f2

f1 > f2

f1 = f2

17 / 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

18 / 50

Cavitation can be prevented by_________?

Maintaining suction head lower than the vapour pressure

Maintaining suction head = developed head

Maintaining the suction head sufficiently greater than the vapour pressure

Suitably designing the pump

19 / 50

Buoyant force___________?

None of these

For non-symmetrical bodies is not vertical

Depends on the depth of the submergence of the floating body

Depends on the weight of the floating body

20 / 50

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

Is independent of body length

Is primarily a friction drag

Occurs when NRe is very small

Depends mainly on cross-sectional shape

21 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

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

Run at a lower speed for the same discharge

Do not need priming

Deliver fluid with pulsating/fluctuating discharge

22 / 50

Differential manometer measures the_____?

Gauge pressure

Pressure gradient

Absolute pressure

Pressure difference

23 / 50

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

Greater than the vapour pressure of the liquid at that temperature

Less than the vapour pressure of the liquid at that temperature

Equal to the vapour pressure

Equal to the developed head

24 / 50

Dimension of absolute viscosity is__________?

ML-1T-1

MLT-1

MLT

ML-1T

25 / 50

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

< 0.1

> 2.5

< 2100

< 500

26 / 50

Curve III in the bellow diagram represents a/an_________?

Ideal plastic

Dilatent fluid

Pseudo plastic fluid

None of these

27 / 50

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

d1/3

d2/3

28 / 50

Dean number is concerned with the______?

Fluid-particle interaction

Fluid flow through helical pipes

Power consumption in agitated vessels

Psychrometry

29 / 50

Differential manometer measures the______?

Sub-atmospheric pressure

Atmospheric pressure

Pressure difference between two points

None of these

30 / 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) ?

FL-2T, ML-1T-1

FLT, ML-1T-1

F-1L2T-1, MLT-3

ML-1T-3, F-1L2T

31 / 50

Dimension of kinematic viscosity is_______?

L2T

MLT-1

L2T-1

L2T-2

32 / 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

33 / 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

34 / 50

Check valve is used for _________ flow?

Multidirectional

Unidirectional

Very precise control of

None of these

35 / 50

Diaphragm pumps are used to transport__________?

Liquids

Solids

Fluids

Slurries

36 / 50

Check valves are used________?

For unidirectional flow

At high pressure

In bends

For controlling water flow

37 / 50

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

Hagen-Poiseuille?s equation

None of these

Navier-stokes equation

Stoke?s law

38 / 50

Cd is always _______ Cc?

Equal to

Greater than

Less than

Either more or less than

39 / 50

Cp/Cv is termed as___________?

Mach number

Weber number

Adiabatic constant

Prandtl number

40 / 50

Choose the set of pressure intensities that are equivalent ?

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

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

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

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

41 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Have lower operating costs

Have quieter operation

All A., B. and C.

Require less space

42 / 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___________?

0.62

0.98

0.42

0.82

43 / 50

Boundary layer separation occurs when the______?

Cross-section of the channel is reduced

Velocity of sound is reached

Valve is closed in a pipeline

Pressure reaches a minimum

44 / 50

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

Either above or below; depends on the liquid density

Below

Above

45 / 50

Centrifugal pump can?t be used to pump _______?

None of the above

Moderately viscous vegetable oil used in soap industry

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

Thick molten soap at 80?C

46 / 50

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

Not related to

Less than

More than

Equal to

47 / 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

48 / 50

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

Keep the pipe in proper orientation

Make the pipe joint leak-proof

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

Account for the pressure variation side the pipeline

49 / 50

Diaphragm valves are used for handling ________ fluids?

Solid suspended

Non-Newtonian

Viscous

Corrosive

50 / 50

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

Discharge pressure

All A., B. and C.

Flow of liquid during operation of the pump

Back flow of fluid in the event of stoppage of pump

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