Fluid Mechanics for Chemical Quiz 3

1 / 50

Choking in case of pipe flow means that a_____?

Valve is closed in the line

Restriction in flow cross-section area occurs

Specified mass flow rate cannot be achieved

None of these

2 / 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

3 / 50

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

Navier-stokes equation

Hagen-Poiseuille?s equation

Stoke?s law

None of these

4 / 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

5 / 50

Cd is always _______ Cc?

Either more or less than

Less than

Greater than

Equal to

6 / 50

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

Flow of liquid during operation of the pump

Discharge pressure

All A., B. and C.

7 / 50

Boundary layer separation occurs when the______?

Pressure reaches a minimum

Velocity of sound is reached

Cross-section of the channel is reduced

Valve is closed in a pipeline

8 / 50

Cocks are used to control _____?

Water

None of these

Solids

Any liquid

9 / 50

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

Inlet pressure high

Inlet pressure low

Outlet pressure low

Outlet pressure high

10 / 50

Cavitation can be prevented by_________?

Maintaining suction head lower than the vapour pressure

Suitably designing the pump

Maintaining the suction head sufficiently greater than the vapour pressure

Maintaining suction head = developed head

11 / 50

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

Is different for different fluids

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

12 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Have lower operating costs

Have quieter operation

All A., B. and C.

Require less space

13 / 50

Differential manometer measures the______?

Pressure difference between two points

None of these

Atmospheric pressure

Sub-atmospheric pressure

14 / 50

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

< 500

> 2.5

< 2100

< 0.1

15 / 50

Dean number is concerned with the______?

Fluid-particle interaction

Psychrometry

Fluid flow through helical pipes

Power consumption in agitated vessels

16 / 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

200 to 300

0.01 to 0.10

2 to 3

17 / 50

Buoyant force___________?

None of these

Depends on the depth of the submergence of the floating body

For non-symmetrical bodies is not vertical

Depends on the weight of the floating body

18 / 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 contraction/expansion of pipe due to temperature changes of the surroundings

Account for the pressure variation side the pipeline

19 / 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

20 / 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

All A., B. and C.

Head of the liquid pumped

BHP required by the pump

21 / 50

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

Either above or below; depends on the liquid density

Below

Above

22 / 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

None of the above

Moderately viscous vegetable oil used in soap industry

23 / 50

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

Back flow through impeller

None of these

Loss of kinetic head

Loss of static head

24 / 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

25 / 50

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

F-2. L

FL-1

F-1. L

F.L-2

26 / 50

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

More than

Equal to

Less than

Not related to

27 / 50

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

Depends mainly on cross-sectional shape

Is primarily a friction drag

Occurs when NRe is very small

Is independent of body length

28 / 50

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

d1/3

d2/3

29 / 50

Cd for the orifice plate varies from _____?

0.58 to 0.8

0.02 to 0.03

0.2 to 0.3

0.93 to 0.98

30 / 50

Dimension of kinematic viscosity is_______?

L2T-1

L2T-2

L2T

MLT-1

31 / 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___________?

0.82

0.42

0.62

0.98

32 / 50

Capacity of a rotary gear pump can be varied by___________?

Bypassing liquid from the suction or discharge line

Changing the speed of rotation

Bleeding air into suction

All A., B. and C.

33 / 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

34 / 50

Dimension of absolute viscosity is__________?

MLT-1

ML-1T-1

MLT

ML-1T

35 / 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

FL-2T, ML-1T-1

FLT, ML-1T-1

F-1L2T-1, MLT-3

36 / 50

Centrifugal pump is normally classified on the basis of the_________?

Number of blades in impeller

Impeller blade angle

Type of casing

rpm

37 / 50

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

1/d

1/?

38 / 50

Differential manometer measures the_____?

Absolute pressure

Pressure difference

Pressure gradient

Gauge pressure

39 / 50

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

d2/3

d1/3

d4/5

40 / 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

Develops high pressure

Increase in thrust

Decrease in effect

41 / 50

Curve III in the bellow diagram represents a/an_________?

Pseudo plastic fluid

Dilatent fluid

None of these

Ideal plastic

42 / 50

Check valves are used________?

In bends

For controlling water flow

At high pressure

For unidirectional flow

43 / 50

Cp/Cv is termed as___________?

Weber number

Mach number

Prandtl number

Adiabatic constant

44 / 50

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

Rate of falling of ram

Amount of energy stored

Flow rate through accumulator

Volume available in the cylinder

45 / 50

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

Equal to the vapour pressure

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 developed head

46 / 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

Generally a globe valve

All A., B. and C.

47 / 50

Diaphragm valves are used for handling ________ fluids?

Non-Newtonian

Solid suspended

Viscous

Corrosive

48 / 50

Diaphragm pumps are used to transport__________?

Solids

Liquids

Fluids

Slurries

49 / 50

Check valve is used for _________ flow?

Multidirectional

None of these

Unidirectional

Very precise control of

50 / 50

Critical velocity in a pipe flow__________?

None of these

Increases as pipe diameter increases

Increases as fluid viscosity increases

Independent of fluid density

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