Fluid Mechanics for Chemical Quiz 3

1 / 50

Choking in case of pipe flow means that a_____?

None of these

Specified mass flow rate cannot be achieved

Valve is closed in the line

Restriction in flow cross-section area occurs

2 / 50

Boundary layer separation occurs when the______?

Pressure reaches a minimum

Cross-section of the channel is reduced

Velocity of sound is reached

Valve is closed in a pipeline

3 / 50

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

Less than the vapour pressure of the liquid at that temperature

Equal to the developed head

Greater than the vapour pressure of the liquid at that temperature

Equal to the vapour pressure

4 / 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?

NPSH required

BHP required by the pump

Head of the liquid pumped

All A., B. and C.

5 / 50

Check in a centrifugal pump is_________?

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

Generally a globe valve

Provided in the discharge line

6 / 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

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

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

7 / 50

Curve III in the bellow diagram represents a/an_________?

Ideal plastic

Pseudo plastic fluid

None of these

Dilatent fluid

8 / 50

Capacity of a rotary gear pump can be varied by___________?

Bleeding air into suction

Changing the speed of rotation

Bypassing liquid from the suction or discharge line

All A., B. and C.

9 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Have quieter operation

All A., B. and C.

Require less space

Have lower operating costs

10 / 50

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

d1/3

d2/3

d4/5

11 / 50

Differential manometer measures the_____?

Pressure difference

Gauge pressure

Absolute pressure

Pressure gradient

12 / 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

13 / 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___________?

0.42

0.82

0.62

0.98

14 / 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

15 / 50

Diaphragm valves are used for handling ________ fluids?

Viscous

Corrosive

Solid suspended

Non-Newtonian

16 / 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

Lies above the centroid of the plane surface

Is at the centroid of the plane surface

Is different for different fluids

17 / 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

18 / 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

19 / 50

Dimension of kinematic viscosity is_______?

L2T

L2T-2

L2T-1

MLT-1

20 / 50

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

Rate of falling of ram

Volume available in the cylinder

Flow rate through accumulator

Amount of energy stored

21 / 50

Cd for the orifice plate varies from _____?

0.02 to 0.03

0.58 to 0.8

0.2 to 0.3

0.93 to 0.98

22 / 50

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

Make the pipe joint leak-proof

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

23 / 50

Critical velocity in a pipe flow__________?

Increases as pipe diameter increases

Independent of fluid density

None of these

Increases as fluid viscosity increases

24 / 50

Diaphragm pumps are used to transport__________?

Fluids

Slurries

Liquids

Solids

25 / 50

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

< 2100

< 0.1

< 500

> 2.5

26 / 50

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

Less than

Not related to

More than

Equal to

27 / 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

28 / 50

Differential manometer measures the______?

Pressure difference between two points

None of these

Sub-atmospheric pressure

Atmospheric pressure

29 / 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) ?

ML-1T-3, F-1L2T

FLT, ML-1T-1

F-1L2T-1, MLT-3

FL-2T, ML-1T-1

30 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

Deliver fluid with pulsating/fluctuating discharge

Run at a lower speed for the same discharge

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

Do not need priming

31 / 50

Buoyant force___________?

Depends on the depth of the submergence of the floating body

None of these

For non-symmetrical bodies is not vertical

Depends on the weight of the floating body

32 / 50

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

Outlet pressure high

Outlet pressure low

Inlet pressure high

Inlet pressure low

33 / 50

Cp/Cv is termed as___________?

Prandtl number

Weber number

Adiabatic constant

Mach number

34 / 50

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

d1/3

d2/3

35 / 50

Centrifugal pump can?t be used to pump _______?

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

Moderately viscous vegetable oil used in soap industry

Thick molten soap at 80?C

None of the above

36 / 50

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

None of these

Stoke?s law

Navier-stokes equation

Hagen-Poiseuille?s equation

37 / 50

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

F-1. L

F-2. L

F.L-2

FL-1

38 / 50

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

Loss of static head

Back flow through impeller

Loss of kinetic head

None of these

39 / 50

Dean number is concerned with the______?

Psychrometry

Fluid flow through helical pipes

Fluid-particle interaction

Power consumption in agitated vessels

40 / 50

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

0.01 to 0.10

100 to 1000

2 to 3

200 to 300

41 / 50

Cocks are used to control _____?

None of these

Solids

Any liquid

Water

42 / 50

Check valves are used________?

For controlling water flow

For unidirectional flow

At high pressure

In bends

43 / 50

Centrifugal pump is normally classified on the basis of the_________?

Type of casing

rpm

Impeller blade angle

Number of blades in impeller

44 / 50

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

Either above or below; depends on the liquid density

Above

Below

45 / 50

Dimension of absolute viscosity is__________?

MLT

ML-1T-1

ML-1T

MLT-1

46 / 50

Cavitation can be prevented by_________?

Maintaining suction head = developed head

Maintaining the suction head sufficiently greater than the vapour pressure

Maintaining suction head lower than the vapour pressure

Suitably designing the pump

47 / 50

Cd is always _______ Cc?

Equal to

Greater than

Either more or less than

Less than

48 / 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

49 / 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

50 / 50

Check valve is used for _________ flow?

Multidirectional

Unidirectional

None of these

Very precise control of

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