Section 5 Flashcards by justin balladares

The ratio of the wall drag to the form drag in the Stoke’s law range (for motion of spherical particles in a stationary fluid) is

A. 0.5
B. 1
C. 2
D. 0.33

C. 2

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For turbulent flow in smooth circular pipe, the velocity distribution is a function of the distance ‘d’ measured from the wall of the pipe and the friction velocity ‘v’, and it follows a __________ relationship.

A. logarithmic
B. linear
C. hyperbolic
D. parabolic

A. logarithmic

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Maintenance cost of a __________ pump for a particular duty is the least.

A. centrifugal
B. reciprocating
C. volute
D. gear

A. centrifugal

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Choking in case of pipe flow means that a

A. specified mass flow rate can not be achieved.
B. valve is closed in the line.
C. restriction in flow cross-section area occurs.
D. none of these.

A. specified mass flow rate can not be achieved.

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Velocity of liquid hydrocarbon fuels in a pipeline can not be measured by magnetic flowmeters, because their __________ is very low/small.

A. thermal conductivity
B. electrical conductivity
C. specific gravity
D. electrical resistivity

B. electrical conductivity

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The nominal size of a hose pipe is specified by its

A. I.D.
B. O.D.
C. thickness
D. none of these

A. I.D.

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Transition from laminar flow to turbulent flow is aided by the

A. surface roughness and curvature (i.e.sharp corners).
B. vibration.
C. pressure gradient and the compressibility of the flowing medium.
D. all (a), (b) & (c).

D. all (a), (b) & (c).

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For flow of fluids through packed bed, the superficial velocity is

A. less than the average velocity through channels.
B. more than the average velocity through channels.
C. dependent on the pressure drop across the bed.
D. same as the average velocity through channels.

A. less than the average velocity through channels.

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Cd is always __________ Cc.

A. greater than
B. less than
C. equal to
D. either more or less than

A. greater than

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Buoyant force

A. for non-symmetrical bodies is not vertical.
B. depends on the depth of the submergence of the floating body.
C. depends on the weight of the floating body.
D. none of these.

C. depends on the weight of the floating body.

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Which of the following is an undesirable property of a manometric liquid ?

A. Non-sticky & non-corrosive nature.
B. High vapour pressure.
C. Low viscosity & surface tension.
D. Low co-efficient of thermal expansion.

B. High vapour pressure.

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The speed of sound in an ideal gas varies as the

A. temperature
B. pressure
C. density
D. none of these

A. temperature

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Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head.

A. manometric
B. total
C. static
D. friction

A. manometric

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The maximum head that can be developed by a single impeller is __________ ft.

A. 25
B. 100
C. 250-300
D. 1000

C. 250-300

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The general relationship between speed N, head H, power P and discharge Q for a centrifugal pump is

A. Q∝N : H∝N2 : P∝N3
B. Q∝N2 : H∝N3 : P∝N
C. Q∝N : H∝N3 : P∝N2
D. Q∝N3 : H∝N : P∝N2

A. Q∝N : H∝N2 : P∝N3

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The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is

A. < 1
B. 1
C. >1
D. 2

A. < 1

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What is the ratio of the velocity at the axis of the pipe to the mean velocity of flow in case of pipe flow under viscous condition ?

A. 0.5
B. 0.67
C. 1
D. 2

D. 2

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Foot valve provided in the pump is a __________ valve.

A. direction control
B. back pressure
C. relief
D. pressure reduction

B. back pressure

The discharge co-efficient for an orificemeter does not depend upon the

A. pipe length.
B. ratio of pipe diameter to orifice diameter.
C. type of orifice & the Reynolds number.
D. pipe diameter.

A. pipe length.

Which of the following options will facilitate the achievement of a very high head (say 30 metres) in case of a centrifugal pump?

A. Increasing the impeller speed and the volute area.
B. Increasing the number of vanes in the impeller.
C. Mounting of two or more impellers in series on a single shaft. D. Either of (a), (b) or (c).

C. Mounting of two or more impellers in series on a single shaft.

An equipotential line is __________ to the velocity vector at every point.

A. normal
B. abnormal
C. tangential
D. none of these

A. normal

Path followed by water jet issuing from the bottom of a water tank will be a

A. parabola (vertex being at the opening).
B. hyperbola.
C. horizontal straight line.
D. zig-zag path (which is geometrically undefined).

A. parabola (vertex being at the opening).

Which of the following produces maximum pressure difference for transportation of gases ?

A. Vaccum pumps
B. Blowers
C. Fans
D. Compressors

D. Compressors

Drag co-efficient in hindered settling is __________ that in free settling.

A. less than
B. equal to
C. not necessarily greater than
D. always greater than

D. always greater than

Efficiency of power transmission (η) through a circular pipe is given by (ht - hf)/ht, which has a maximum value of __________ percent. A. 33:3 B. 50 C. 66.6 D. 88.8

C. 66.6

One dimensional fluid flow implies the A. flow in straight lines only. B. uniform flow. C. steady uniform flow. D. flow in which transverse components are zero.

D. flow in which transverse components are zero.

__________ forces act on a particle moving through a stationary fluid. A. Gravity B. Drag C. Buoyant D. all (a), (b), & (c)

D. all (a), (b), & (c)

Hydraulic radius is the ratio of A. wetted perimeter to flow area. B. flow area to wetted perimeter. C. flow area to square of wetted perimeter. D. square root of flow area to wetted perimeter.

B. flow area to wetted perimeter.

The unit of bulk modulus of elasticity for a liquid in S.I. unit is A. N B. N/m C. N/m^2 D. N/m^3

C. N/m^2

Power requirement of fans having constant wheel diameter varies __________ fan speed. A. as square of B. directly as C. as cube of D. none of these

C. as cube of

In the low Reynolds number region, the drag force on a sphere is proportional to A. V B. V^2 C. V^4 D. V^0.5

A. V

The continuity equation A. is independent of the compressibility of the fluid. B. is dependent upon the viscosity of the fluid. C. represents the conservation of mass. D. none of these.

C. represents the conservation of mass.

Experimental study of laminar fluid flow through a circular tube was conducted by A. Reynolds B. Hagen and Poiseuille C. Pascal D. Blake-Plummer

B. Hagen and Poiseuille

The most economical flow control valve for use with large diameter pipes is a A. butterfly valve B. globe valve C. needle valve D. none of these

A. butterfly valve

Each term in Bernaulli's equation represents the __________ of the fluid. A. energy per unit mass B. energy per unit weight C. force per unit mass D. none of these

B. energy per unit weight

Which of the following is a dimensionless parameter ? A. Angular velocity B. Specific weight C. Kinematic viscosity D. None of these

D. None of these

If the head over the triangular notch is doubled, the discharge will increase by __________ times. A. 2 B. 2.828 C. 5.657 D. 4

C. 5.657

Friction factor for a hydraulically smooth pipe at NRe = 2100 is f1. If the pipe is further smoothened (i.e., roughness is reduced), the friction factor at the same value of NRe, will A. increase. B. decrease. C. remain unchanged. D. increase or decrease depending on the pipe material.

A. increase.

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. A. NPSH required. B. BHP required by the pump. C. head of the liquid pumped. D. all (a), (b) and (c).

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

For the laminar flow of a fluid in a circular pipe of radius R, the Hagen- Poisseule equation predicts the volumetric flow rate to be proportional to A. R B. R^2 C. R^4 D. R^0.5

C. R^4

Interstage coolers are provided in a multistage compressor to A. save power in compressing a given volume to a given pressure. B. cool the delivered air. C. achieve the exact delivery pressure. D. none of these.

A. save power in compressing a given volume to a given pressure.

Reynolds number is the ratio of A. viscous forces to gravity forces. B. inertial forces to viscous forces. C. viscous forces to inertial forces. D. inertial forces to gravity forces.

B. inertial forces to viscous forces.

The discharge through a venturimeter depends upon A. pressure drop only. B. its orientation. C. co-efficient of contraction only. D. none of these.

A. pressure drop only.

N. second/m^2 is A. the S.I. unit of dynamic viscosity. B. the S.I. unit of kinematic viscosity. C. equivalent to one poise. D. equivalent to one stoke.

A. the S.I. unit of dynamic viscosity.