Section 14

Question 1

The terminal velocity of a solid spherical particle falling through a stationary fluid mass in the Stoke’s law range is proportional to the

a. inverse of fluid viscosity.
b. square of particle size.
c. difference in the densities of the particle & fluid.
d. all (a), (b) and (c).

Answer 1

d. all (a), (b) and (c).

Question 2

Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (ε0) with age/time (t) (where, ε = roughness of the surface after time’t’. α = a co-efficient to be experimentally determined)?

a. ε = ε0 + α.t
b. ε = ε0 + α.t^2
c. ε = ε0 + α.t^3
d. ε = ε0 + α.t^4

Answer 2

a. ε = ε0 + α.t

Question 2

Nominal size of a pipe is an indication of its __________ diameter.

a. inner
b. outer
c. approximate
d. none of these

Answer 2

c. approximate

Question 3

Fluidised beds are formed, when the

a. fluid friction is zero
b. gravity force is less than the fluid friction.
c. pressure forces equal gravity forces.
d. sum of the fluid friction and pressure forces is equal and opposite to gravity forces.

Answer 3

b. gravity force is less than the fluid friction.

Question 3

A fluid is pumped at the rate of 10 lb/sec to a height of 55 ft. The horse power required is __________ hp.

a. 1
b. 10/55
c. 5.5
d. 1/55

Answer 3

a. 1

Question 4

Pick out the wrong statement:

a. The vacuum pressure is always the negative gauge pressure.
b. The pressure of the liquid measured by a piezometer tube is the gauge pressure.
c. Manometric liquid should have high surface tension.
d. The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity.

Answer 4

d. The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity.

Question 5

Medium viscosity lubricating oil can be most ideally pumped by a __________ pump.
a. vane
b. piston
c. centrifugal
d. plunger

Answer 5

a. vane

Question 6

In a fully turbulent flow (Re > 105) in a pipe of diameter ‘d’, for a constant pressure gradient, the dependence of volumetric flow rate of an incompressible fluid is

a. d
b. d^2
c. d^2.5
d. d^4

Answer 6

c. d^2.5

Question 7

Pump used for the transportation of molten sodium in a fast breader reactor is a/an __________ pump.

a. reciprocating
b. plunger
c. electromagnetic
d. gear

Answer 7

c. electromagnetic

Question 8

Small pressure differences in liquids is measured using a/an

a. U-tube manometer.
b. inclined tube manometer.
c. pitot tube.
d. none of these.

Answer 8

b. inclined tube manometer.

Question 9

With increase in pump speed, its NPSH requirement

a. decreases
b. increases
c. remains unaltered
d. can either increase or decrease ; depends on other factors

Answer 9

b. increases

Question 10

In the Newton’s law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass is __________ the fluid viscosity.

a. directly proportional to
b. inversely proportional to
c. inversely proportional to the square root of
d. independent of

Answer 10

b. inversely proportional to

Question 11

Gear pump

a. is a positive displacement pump.
b. is a centrifugal pump.
c. is a non-positive displacement pump.
d. can be started with delivery valve closed.

Answer 11

a. is a positive displacement pump.

Question 12

Most of the centrifugal pumps used in chemical plants are usually __________ driven.

a. steam
b. diesel engine
c. electric motor
d. gas turbine

Answer 12

c. electric motor

Question 13

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

a. back flow of fluid in the event of stoppage of pump.
b. discharge pressure.
c. Flow of liquid during operation of the pump.
d. all (a), (b) and (c).

Answer 13

d. all (a), (b) and (c).

Question 14

Venturimeters, orificemeters and nozzles are used to measure the fluid discharge from a pipeline. The average fluid velocity in a pipeline can be measured by a/an

a. weir
b. hot wire anemometer
c. cup and vane aneometer
d. none of these

Answer 14

b. hot wire anemometer

Question 15

The time taken for gravity flow of a fixed volume of liquid (as in Redwood viscometer) is directly proportional to its

a. absolute viscosity.
b. ratio of absolute viscosity to density.
c. density.
d. Reynolds number.

Answer 15

b. ratio of absolute viscosity to density.

Question 16

Sewage sludge is __________ type of non-Newtonion fluid.

a. dilatant
b. Bingham plastic
c. Pseudo plastic
d. none of these

Answer 16

b. Bingham plastic

Question 17

Ratio of pressure and inertia force gives __________ number.

a. Weber
b. Mach
c. Euler
d. Froude

Answer 17

c. Euler

Question 18

Permanent loss in a venturimeter is about __________ percent of the pressure drop in theupstream cone.

a. 1
b. 10
c. 40
d. 70

Answer 18

b. 10

Question 19

Volume of liquid displaced by a floating body is equivalent to its

a. own weight
b. submerged weight
c. own volume
d. submerged volume

Answer 19

a. own weight

Question 20

The __________ is measured by a piezometric opening.

a. dynamic pressure
b. static pressure
c. total pressure
d. point velocity

Answer 20

c. total pressure

Question 21

What is the pipe called which lifts water from a reservoir to a greater height than the initial level in the supply reservoir ?

a. Penstock
b. Siphon
c. Tunnel
d. Pressure pipeline

Answer 21

b. Siphon

Question 22

Steady uniform flow is represented by flow through a/an

a. long pipe at constant rate.
b. long pipe at decreasing rate.
c. expanding tube at constant rate.
d. none of these.

Answer 22

a. long pipe at constant rate.

Question 23

Pick out the correct statement pertaining to the flow through a converging diverging tube. a. The value of Mach number is always unity at the throat. b. No shock wave develops in the tube when the Mach number at exit is greater than unity. c. Throughout the converging portion of the tube, the density increases in the downstream direction. d. none of these.

Answer 23

b. No shock wave develops in the tube when the Mach number at exit is greater than unity.

Question 24

Cavitation can be prevented by a. suitably designing the pump. b. maintaining the suction head sufficiently greater than the vapour pressure. c. maintaining suction head = developed head. d. maintaining suction head lower than the vapour pressure.

Answer 24

b. maintaining the suction head sufficiently greater than the vapour pressure.

Question 25

Assuming flow to be laminar, if the diameter of the pipe is halved, then the pressure drop will a. increase b. decrease c. remain same d. be quadrupled

Answer 25

a. increase

Question 26

Steady flow occurs, when the a. conditions change steadily with time. b. conditions are the same at the adjacent points at any instant. c. conditions do not change with time at any point. d. rate of the velocity change is constant.

Answer 26

c. conditions do not change with time at any point.

Question 27

With increase in the ratio of orifice diameter to pipe diameter, the fraction of the orifice pressure differential that is permanently lost a. increases b. decreases c. remains unchanged d. increases exponentially

Answer 27

b. decreases

Question 28

Which of the following two quantities when same, makes one pipe system equivalent to another pipe system ? a. Head & discharge b. Length & discharge c. Length & diameter d. Friction factor & diameter.

Answer 28

a. Head & discharge

Question 29

The kinetic energy correction factor for velocity distribution of laminar flow is a. 0.5 b. 1.66 c. 1 d. 2

Answer 29

b. 1.66

Question 30

Priming of a centrifugal pump is done to a. increase the mass flow rate of fluid. b. develop effective pressure rise by the pump. c. avoid chances of separation inside the impeller. d. none of these.

Answer 30

c. avoid chances of separation inside the impeller.

Question 31

Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 200 kg/m3, Dp = 0.05 cm) of 60 cm bed depth and bed porosity of 0.5 expressed in cm of water (manometer) is a. 90 b. 60 c. 45 d. 30

Answer 31

b. 60

Question 32

For pipes that must be broken at intervals for maintenance, the connector used should be a/an a. union b. tee c. reducer d. elbow

Answer 32

a. union

Question 33

A fluid is the one, which a. cannot remain at rest under the action of shear force. b. continuously expands till it fills any container. c. is incompressible. d. permanently resists distortion.

Answer 33

a. cannot remain at rest under the action of shear force.

Question 34

One horsepower is equal to a.550 lbf.ft/second b. 550 kgf.m/second c. both (a) and (b) d. 550 lbf.ft./hr

Answer 34

a.550 lbf.ft/second

Question 35

A fluid is moving at critical flow condition (NRe = 2100) through a pipe of dia 3 cms. Velocity of flow is __________ cm/sec. a. 7 b. 700 c. 7000 d. 630

Answer 35

a. 7

Question 36

Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, σ = surface tension of mercury) a. d b. 1/d c. σ d. l/σ

Answer 36

c. σ

Question 37

The pressure drop per unit length of pipe incurred by a fluid 'X' flowing through pipe is Δp. If another fluid 'Y' having both the specific gravity & density just double of that of fluid 'X', flows through the same pipe at the same flow rate/average velocity, then the pressure drop in this case will be A. Δp b. 2Δp c. Δp2 d. Δp/2

Answer 37

b. 2Δp

Question 38

Fluid flow in a/an __________ is an example of pressure flow. a. partially filled pipeline b. pipe c. open channel d. river.

Answer 38

b. pipe

Question 39

In the laminar boundary layer flow over a flat plate, the ratio (δ/x) varies as :(where, 'δ' is the boundary layer thickness and 'x' is the distance from the leading edge in the direction of flow). a. Re b. √𝑅𝑒 c. 1/Re d. Re^-1/2

Answer 39

d. Re^-1/2

Question 40

A rotameter through which air at room temperature and atmospheric pressure is flowing gives a certain reading for a flow rate of 100 cc/sec. If helium (molecular weight 4) is used and rotameter shows the same reading, the flow rate (cc/sec) is a. 26 b. 42 c. 269 d. 325

Answer 40

c. 269

Question 41

A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m3 ) is to be fluidised by water (density 1000 kg/m3 ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is a. 4.4 KPa b. 2.94 KPa c. 3.7 KPa d. none of these

Answer 41

a. 4.4 KPa

Question 42

Select the wrong statement pertaining to flow of an incompressible fluid through a venturimeter. a. For frictionless flow, the fluid pressure entering the venturi meter will be exactly equal to that leaving the venturimeter. b. Discharge of fluid through a venturimeter depends upon the gage difference irrespective of the orientation of venturimeter. c. Venturimeter occupies less space than an orificemeter. d. Venturimeter incurs less power loss compared to an equivalent

Answer 42

c. Venturimeter occupies less space than an orificemeter.

Question 43

Reynolds number for water flow through a tube of I.D. 5 cm is 1500. If a liquid of 5 centipoise viscosity and 0.8 specific gravity flows in the same pipe at the same velocity, then the pressure drop will a. increase b. decrease c. remain same d. data insufficient to predict pressure drop

Answer 43

a. increase

Question 44

The bulk modulus of elasticity of a liquid a. is zero for incompressible liquid. b. decreases with pressure. c. Is independent of temperature & pressure. d. increases with pressure.

Answer 44

d. increases with pressure.