Fluid Mechanics for Chemical Quiz 3

1 / 50

Critical velocity in a pipe flow__________?

Independent of fluid density

None of these

Increases as pipe diameter increases

Increases as fluid viscosity increases

2 / 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

3 / 50

Curve III in the bellow diagram represents a/an_________?

Pseudo plastic fluid

Ideal plastic

Dilatent fluid

None of these

4 / 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

5 / 50

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

Stoke?s law

Navier-stokes equation

None of these

Hagen-Poiseuille?s equation

6 / 50

Capacity of a rotary gear pump can be varied by___________?

Bypassing liquid from the suction or discharge line

All A., B. and C.

Changing the speed of rotation

Bleeding air into suction

7 / 50

Dean number is concerned with the______?

Psychrometry

Fluid-particle interaction

Power consumption in agitated vessels

Fluid flow through helical pipes

8 / 50

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

F-2. L

F.L-2

FL-1

F-1. L

9 / 50

Cavitation can be prevented by_________?

Maintaining suction head = developed head

Suitably designing the pump

Maintaining the suction head sufficiently greater than the vapour pressure

Maintaining suction head lower than the vapour pressure

10 / 50

Check valves are used________?

In bends

For controlling water flow

For unidirectional flow

At high pressure

11 / 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

12 / 50

Cp/Cv is termed as___________?

Mach number

Weber number

Prandtl number

Adiabatic constant

13 / 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

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

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

14 / 50

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

d2/3

d1/3

15 / 50

Centrifugal pump is normally classified on the basis of the_________?

Impeller blade angle

rpm

Type of casing

Number of blades in impeller

16 / 50

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

200 to 300

100 to 1000

2 to 3

0.01 to 0.10

17 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

Run at a lower speed for the same discharge

Do not need priming

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

Deliver fluid with pulsating/fluctuating discharge

18 / 50

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

Is primarily a friction drag

Is independent of body length

Depends mainly on cross-sectional shape

Occurs when NRe is very small

19 / 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

NPSH required

Head of the liquid pumped

20 / 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

0.98

0.62

21 / 50

Cd is always _______ Cc?

Less than

Greater than

Equal to

Either more or less than

22 / 50

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

> 2.5

< 500

< 0.1

< 2100

23 / 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

24 / 50

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

Rate of falling of ram

Volume available in the cylinder

Amount of energy stored

Flow rate through accumulator

25 / 50

Dimension of absolute viscosity is__________?

MLT

ML-1T-1

ML-1T

MLT-1

26 / 50

Cocks are used to control _____?

None of these

Water

Any liquid

Solids

27 / 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

28 / 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

29 / 50

Diaphragm valves are used for handling ________ fluids?

Solid suspended

Corrosive

Viscous

Non-Newtonian

30 / 50

Cd for the orifice plate varies from _____?

0.02 to 0.03

0.93 to 0.98

0.58 to 0.8

0.2 to 0.3

31 / 50

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

Develops high pressure

Develops noise

Increase in thrust

Decrease in effect

32 / 50

Centrifugal pump can?t be used to pump _______?

Thick molten soap at 80?C

None of the above

Moderately viscous vegetable oil used in soap industry

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

33 / 50

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

Outlet pressure high

Inlet pressure high

Outlet pressure low

Inlet pressure low

34 / 50

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

Either above or below; depends on the liquid density

Below

Above

35 / 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

Account for the pressure variation side the pipeline

Keep the pipe in proper orientation

36 / 50

Diaphragm pumps are used to transport__________?

Fluids

Slurries

Liquids

Solids

37 / 50

Boundary layer separation occurs when the______?

Velocity of sound is reached

Cross-section of the channel is reduced

Pressure reaches a minimum

Valve is closed in a pipeline

38 / 50

Check valve is used for _________ flow?

Unidirectional

Very precise control of

None of these

Multidirectional

39 / 50

Centrifugal compressors compared to reciprocating compressors___________?

All A., B. and C.

Require less space

Have lower operating costs

Have quieter operation

40 / 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

41 / 50

Dimension of kinematic viscosity is_______?

L2T-2

L2T

MLT-1

L2T-1

42 / 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

43 / 50

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

Loss of kinetic head

None of these

Loss of static head

Back flow through impeller

44 / 50

Differential manometer measures the_____?

Pressure difference

Absolute pressure

Gauge pressure

Pressure gradient

45 / 50

Check in a centrifugal pump is_________?

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

All A., B. and C.

46 / 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 independent of the specific weight of the fluid

Is different for different fluids

Is at the centroid of the plane surface

47 / 50

Differential manometer measures the______?

Pressure difference between two points

Atmospheric pressure

None of these

Sub-atmospheric pressure

48 / 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

49 / 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

ML-1T-3, F-1L2T

F-1L2T-1, MLT-3

FLT, ML-1T-1

50 / 50

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

More than

Not related to

Equal to

Less than

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