Fluid Mechanics for Chemical Quiz 3

1 / 50

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

Lies above the centroid of the plane surface

Is different for different fluids

Is at the centroid of the plane surface

Is independent of the specific weight of the fluid

2 / 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/?

3 / 50

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

d2/3

d4/5

d1/3

4 / 50

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

Above

Either above or below; depends on the liquid density

Below

5 / 50

Choking in case of pipe flow means that a_____?

Restriction in flow cross-section area occurs

None of these

Valve is closed in the line

Specified mass flow rate cannot be achieved

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?

All A., B. and C.

NPSH required

Head of the liquid pumped

BHP required by the pump

7 / 50

Cocks are used to control _____?

Solids

None of these

Any liquid

Water

8 / 50

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

< 2100

< 500

> 2.5

< 0.1

9 / 50

Check valves are used________?

At high pressure

For controlling water flow

For unidirectional flow

In bends

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

Buoyant force___________?

For non-symmetrical bodies is not vertical

None of these

Depends on the weight of the floating body

Depends on the depth of the submergence of the floating body

12 / 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

13 / 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

Decrease in effect

Develops high pressure

Increase in thrust

14 / 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

0.42

0.82

0.62

15 / 50

Diaphragm valves are used for handling ________ fluids?

Non-Newtonian

Corrosive

Solid suspended

Viscous

16 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Require less space

Have lower operating costs

All A., B. and C.

Have quieter operation

17 / 50

Dimension of kinematic viscosity is_______?

L2T

MLT-1

L2T-1

L2T-2

18 / 50

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

None of these

Loss of static head

Back flow through impeller

Loss of kinetic head

19 / 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

2 to 3

200 to 300

100 to 1000

20 / 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

FLT, ML-1T-1

FL-2T, ML-1T-1

21 / 50

Differential manometer measures the______?

None of these

Pressure difference between two points

Atmospheric pressure

Sub-atmospheric pressure

22 / 50

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

Hagen-Poiseuille?s equation

Stoke?s law

None of these

Navier-stokes equation

23 / 50

Check in a centrifugal pump is_________?

Provided in the discharge line

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

24 / 50

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

Volume available in the cylinder

Flow rate through accumulator

Rate of falling of ram

Amount of energy stored

25 / 50

Critical velocity in a pipe flow__________?

Increases as fluid viscosity increases

None of these

Increases as pipe diameter increases

Independent of fluid density

26 / 50

Differential manometer measures the_____?

Pressure gradient

Absolute pressure

Pressure difference

Gauge pressure

27 / 50

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

F-1. L

F.L-2

FL-1

F-2. L

28 / 50

Cp/Cv is termed as___________?

Adiabatic constant

Mach number

Prandtl number

Weber number

29 / 50

Choose the set of pressure intensities that are equivalent ?

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

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

30 / 50

Cd for the orifice plate varies from _____?

0.2 to 0.3

0.58 to 0.8

0.02 to 0.03

0.93 to 0.98

31 / 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 vapour pressure

Greater than the vapour pressure of the liquid at that temperature

Equal to the developed head

32 / 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

33 / 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

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 pumps as compared to reciprocating pumps___________?

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

Deliver fluid with pulsating/fluctuating discharge

Do not need priming

Run at a lower speed for the same discharge

36 / 50

Dean number is concerned with the______?

Psychrometry

Fluid-particle interaction

Fluid flow through helical pipes

Power consumption in agitated vessels

37 / 50

Check valve is used for _________ flow?

Multidirectional

Unidirectional

None of these

Very precise control of

38 / 50

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

Outlet pressure high

Inlet pressure low

Outlet pressure low

Inlet pressure high

39 / 50

Curve III in the bellow diagram represents a/an_________?

Dilatent fluid

None of these

Pseudo plastic fluid

Ideal plastic

40 / 50

Cd is always _______ Cc?

Equal to

Less than

Either more or less than

Greater than

41 / 50

Centrifugal pump is normally classified on the basis of the_________?

Impeller blade angle

rpm

Type of casing

Number of blades in impeller

42 / 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

All A., B. and C.

Discharge pressure

43 / 50

Capacity of a rotary gear pump can be varied by___________?

Changing the speed of rotation

All A., B. and C.

Bleeding air into suction

Bypassing liquid from the suction or discharge line

44 / 50

Centrifugal pump can?t be used to pump _______?

Thick molten soap at 80?C

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

Moderately viscous vegetable oil used in soap industry

None of the above

45 / 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

46 / 50

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

Less than

Not related to

Equal to

More than

47 / 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

48 / 50

Diaphragm pumps are used to transport__________?

Fluids

Liquids

Solids

Slurries

49 / 50

Dimension of absolute viscosity is__________?

ML-1T

MLT-1

MLT

ML-1T-1

50 / 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

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