Fluid Mechanics for Chemical Quiz 3

1 / 50

Choking in case of pipe flow means that a_____?

Specified mass flow rate cannot be achieved

Restriction in flow cross-section area occurs

None of these

Valve is closed in the line

2 / 50

Check in a centrifugal pump is_________?

Provided in the discharge line

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

All A., B. and C.

Generally a globe valve

3 / 50

Differential manometer measures the______?

Sub-atmospheric pressure

Atmospheric pressure

None of these

Pressure difference between two points

4 / 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

5 / 50

Boundary layer separation occurs when the______?

Valve is closed in a pipeline

Pressure reaches a minimum

Cross-section of the channel is reduced

Velocity of sound is reached

6 / 50

Check valves are used________?

For unidirectional flow

In bends

For controlling water flow

At high pressure

7 / 50

Cavitation can be prevented by_________?

Maintaining suction head lower than the vapour pressure

Suitably designing the pump

Maintaining suction head = developed head

Maintaining the suction head sufficiently greater than the vapour pressure

8 / 50

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

Either above or below; depends on the liquid density

Below

Above

9 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Require less space

Have quieter operation

Have lower operating costs

All A., B. and C.

10 / 50

Curve III in the bellow diagram represents a/an_________?

Pseudo plastic fluid

Dilatent fluid

None of these

Ideal plastic

11 / 50

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

Loss of static head

Loss of kinetic head

None of these

Back flow through impeller

12 / 50

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

Stoke?s law

Navier-stokes equation

None of these

Hagen-Poiseuille?s equation

13 / 50

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

F-2. L

F.L-2

F-1. L

FL-1

14 / 50

Dimension of kinematic viscosity is_______?

L2T

MLT-1

L2T-2

L2T-1

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?

All A., B. and C.

BHP required by the pump

Head of the liquid pumped

NPSH required

16 / 50

Cocks are used to control _____?

Water

None of these

Solids

Any liquid

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

Develops noise

Increase in thrust

Decrease in effect

Develops high pressure

19 / 50

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

d4/5

d2/3

d1/3

20 / 50

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

Keep the pipe in proper orientation

Account for the pressure variation side the pipeline

Make the pipe joint leak-proof

21 / 50

Choose the set of pressure intensities that are equivalent ?

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

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

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

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

22 / 50

Dean number is concerned with the______?

Psychrometry

Power consumption in agitated vessels

Fluid flow through helical pipes

Fluid-particle interaction

23 / 50

Cd is always _______ Cc?

Either more or less than

Equal to

Greater than

Less than

24 / 50

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

Is at the centroid of the plane surface

Lies above the centroid of the plane surface

Is independent of the specific weight of the fluid

Is different for different fluids

25 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

Do not need priming

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

Run at a lower speed for the same discharge

Deliver fluid with pulsating/fluctuating discharge

26 / 50

Cp/Cv is termed as___________?

Prandtl number

Weber number

Mach number

Adiabatic constant

27 / 50

Check valve is used for _________ flow?

Multidirectional

Very precise control of

None of these

Unidirectional

28 / 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) ?

F-1L2T-1, MLT-3

ML-1T-3, F-1L2T

FL-2T, ML-1T-1

FLT, ML-1T-1

29 / 50

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

Occurs when NRe is very small

Is primarily a friction drag

Depends mainly on cross-sectional shape

Is independent of body length

30 / 50

Centrifugal pump is normally classified on the basis of the_________?

Type of casing

Number of blades in impeller

Impeller blade angle

rpm

31 / 50

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

Amount of energy stored

Volume available in the cylinder

Rate of falling of ram

Flow rate through accumulator

32 / 50

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

d1/3

d2/3

33 / 50

Capacity of a rotary gear pump can be varied by___________?

All A., B. and C.

Bypassing liquid from the suction or discharge line

Changing the speed of rotation

Bleeding air into suction

34 / 50

Centrifugal pump can?t be used to pump _______?

None of the above

Thick molten soap at 80?C

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

Moderately viscous vegetable oil used in soap industry

35 / 50

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

Outlet pressure high

Inlet pressure low

Inlet pressure high

Outlet pressure low

36 / 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

0.01 to 0.10

2 to 3

200 to 300

37 / 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

f1 > f2

Data not sufficient to relate f1 & f2

38 / 50

Dimension of absolute viscosity is__________?

ML-1T-1

ML-1T

MLT

MLT-1

39 / 50

Critical velocity in a pipe flow__________?

None of these

Increases as fluid viscosity increases

Independent of fluid density

Increases as pipe diameter increases

40 / 50

Diaphragm valves are used for handling ________ fluids?

Solid suspended

Non-Newtonian

Viscous

Corrosive

41 / 50

Cd for the orifice plate varies from _____?

0.2 to 0.3

0.58 to 0.8

0.93 to 0.98

0.02 to 0.03

42 / 50

Buoyant force___________?

None of these

For non-symmetrical bodies is not vertical

Depends on the weight of the floating body

Depends on the depth of the submergence of the floating body

43 / 50

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

< 0.1

< 500

< 2100

> 2.5

44 / 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

45 / 50

Differential manometer measures the_____?

Absolute pressure

Pressure gradient

Pressure difference

Gauge pressure

46 / 50

Diaphragm pumps are used to transport__________?

Liquids

Fluids

Slurries

Solids

47 / 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

0.82

0.42

48 / 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

49 / 50

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

All A., B. and C.

Back flow of fluid in the event of stoppage of pump

Flow of liquid during operation of the pump

Discharge pressure

50 / 50

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

Not related to

Equal to

Less than

More than

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