Fluid Mechanics for Chemical Quiz 3

1 / 50

Buoyant force___________?

For non-symmetrical bodies is not vertical

Depends on the depth of the submergence of the floating body

Depends on the weight of the floating body

None of these

2 / 50

Diaphragm valves are used for handling ________ fluids?

Corrosive

Viscous

Non-Newtonian

Solid suspended

3 / 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

Depends mainly on cross-sectional shape

Occurs when NRe is very small

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 developed head

Equal to the vapour pressure

5 / 50

Differential manometer measures the_____?

Absolute pressure

Pressure difference

Pressure gradient

Gauge pressure

6 / 50

Capacity of a rotary gear pump can be varied by___________?

All A., B. and C.

Bleeding air into suction

Changing the speed of rotation

Bypassing liquid from the suction or discharge line

7 / 50

Centrifugal compressors compared to reciprocating compressors___________?

Require less space

All A., B. and C.

Have lower operating costs

Have quieter operation

8 / 50

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

d4/5

d1/3

d2/3

9 / 50

Check valve is used for _________ flow?

None of these

Multidirectional

Very precise control of

Unidirectional

10 / 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

0.82

0.62

0.42

11 / 50

Centrifugal pump is normally classified on the basis of the_________?

Type of casing

Number of blades in impeller

rpm

Impeller blade angle

12 / 50

Centrifugal pump can?t be used to pump _______?

Moderately viscous vegetable oil used in soap industry

Thick molten soap at 80?C

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

None of the above

13 / 50

Boundary layer separation occurs when the______?

Cross-section of the channel is reduced

Velocity of sound is reached

Pressure reaches a minimum

Valve is closed in a pipeline

14 / 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

15 / 50

Choose the set of pressure intensities that are equivalent ?

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

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

16 / 50

Dean number is concerned with the______?

Psychrometry

Fluid flow through helical pipes

Fluid-particle interaction

Power consumption in agitated vessels

17 / 50

Dimension of kinematic viscosity is_______?

L2T

L2T-1

MLT-1

L2T-2

18 / 50

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

Not related to

Equal to

More than

Less than

19 / 50

Dimension of absolute viscosity is__________?

MLT-1

ML-1T

MLT

ML-1T-1

20 / 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 at the centroid of the plane surface

Is independent of the specific weight of the fluid

Lies above the centroid of the plane surface

21 / 50

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

< 500

< 2100

> 2.5

< 0.1

22 / 50

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

d1/3

d2/3

23 / 50

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

Increase in thrust

Develops noise

Decrease in effect

Develops high pressure

24 / 50

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

Flow rate through accumulator

Rate of falling of ram

Volume available in the cylinder

Amount of energy stored

25 / 50

Choking in case of pipe flow means that a_____?

Valve is closed in the line

Specified mass flow rate cannot be achieved

None of these

Restriction in flow cross-section area occurs

26 / 50

Centrifugal pumps as compared to reciprocating pumps___________?

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

Run at a lower speed for the same discharge

Do not need priming

Deliver fluid with pulsating/fluctuating discharge

27 / 50

Diaphragm pumps are used to transport__________?

Solids

Fluids

Liquids

Slurries

28 / 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/?

29 / 50

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

Outlet pressure low

Inlet pressure low

Inlet pressure high

Outlet pressure high

30 / 50

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

Navier-stokes equation

Stoke?s law

None of these

Hagen-Poiseuille?s equation

31 / 50

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

Make the pipe joint leak-proof

Account for the pressure variation side the pipeline

Account for contraction/expansion of pipe due to temperature changes of the surroundings

Keep the pipe in proper orientation

32 / 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

F-1L2T-1, MLT-3

FL-2T, ML-1T-1

FLT, ML-1T-1

33 / 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?

Head of the liquid pumped

All A., B. and C.

BHP required by the pump

NPSH required

34 / 50

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

Flow of liquid during operation of the pump

All A., B. and C.

Discharge pressure

Back flow of fluid in the event of stoppage of pump

35 / 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

Provided in the discharge line

All A., B. and C.

Generally a globe valve

36 / 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

37 / 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

38 / 50

Critical velocity in a pipe flow__________?

Increases as fluid viscosity increases

Independent of fluid density

Increases as pipe diameter increases

None of these

39 / 50

Cd is always _______ Cc?

Either more or less than

Equal to

Greater than

Less than

40 / 50

Cd for the orifice plate varies from _____?

0.58 to 0.8

0.93 to 0.98

0.2 to 0.3

0.02 to 0.03

41 / 50

Cocks are used to control _____?

Water

None of these

Any liquid

Solids

42 / 50

Curve III in the bellow diagram represents a/an_________?

Pseudo plastic fluid

Ideal plastic

Dilatent fluid

None of these

43 / 50

Check valves are used________?

At high pressure

In bends

For controlling water flow

For unidirectional flow

44 / 50

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

Loss of static head

Back flow through impeller

None of these

Loss of kinetic head

45 / 50

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

Above

Below

Either above or below; depends on the liquid density

46 / 50

Differential manometer measures the______?

Sub-atmospheric pressure

None of these

Pressure difference between two points

Atmospheric pressure

47 / 50

Cp/Cv is termed as___________?

Mach number

Prandtl number

Adiabatic constant

Weber number

48 / 50

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

FL-1

F-1. L

F-2. L

F.L-2

49 / 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

0.01 to 0.10

2 to 3

50 / 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

Data not sufficient to relate f1 & f2

f1 < f2

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