Section 14 Flashcards
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).
d. all (a), (b) and (c).
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
a. ε = ε0 + α.t
Nominal size of a pipe is an indication of its __________ diameter.
a. inner
b. outer
c. approximate
d. none of these
c. approximate
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.
b. gravity force is less than the fluid friction.
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
a. 1
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.
d. The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity.
Medium viscosity lubricating oil can be most ideally pumped by a __________ pump.
a. vane
b. piston
c. centrifugal
d. plunger
a. vane
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
c. d^2.5
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
c. electromagnetic
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.
b. inclined tube manometer.
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
b. increases
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
b. inversely proportional to
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.
a. is a positive displacement pump.
Most of the centrifugal pumps used in chemical plants are usually __________ driven.
a. steam
b. diesel engine
c. electric motor
d. gas turbine
c. electric motor
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).
d. all (a), (b) and (c).
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
b. hot wire anemometer
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.
b. ratio of absolute viscosity to density.
Sewage sludge is __________ type of non-Newtonion fluid.
a. dilatant
b. Bingham plastic
c. Pseudo plastic
d. none of these
b. Bingham plastic
Ratio of pressure and inertia force gives __________ number.
a. Weber
b. Mach
c. Euler
d. Froude
c. Euler
Permanent loss in a venturimeter is about __________ percent of the pressure drop in theupstream cone.
a. 1
b. 10
c. 40
d. 70
b. 10
Volume of liquid displaced by a floating body is equivalent to its
a. own weight
b. submerged weight
c. own volume
d. submerged volume
a. own weight
The __________ is measured by a piezometric opening.
a. dynamic pressure
b. static pressure
c. total pressure
d. point velocity
c. total pressure
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
b. Siphon
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.
a. long pipe at constant rate.
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.
b. No shock wave develops in the tube when the Mach number at exit is greater than unity.
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.
b. maintaining the suction head sufficiently greater than the vapour pressure.
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
a. increase
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.
c. conditions do not change with time at any point.
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
b. decreases
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.
a. Head & discharge
The kinetic energy correction factor for velocity distribution of laminar flow is
a. 0.5
b. 1.66
c. 1
d. 2
b. 1.66
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.
c. avoid chances of separation inside the impeller.
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
b. 60
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
a. union
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.
a. cannot remain at rest under the action of shear force.
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
a.550 lbf.ft/second
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
a. 7
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
c. σ
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
b. 2Δp
Fluid flow in a/an __________ is an example of pressure flow.
a. partially filled pipeline
b. pipe
c. open channel
d. river.
b. pipe
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
d. Re^-1/2
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
c. 269
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
a. 4.4 KPa
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
c. Venturimeter occupies less space than an orificemeter.
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
a. increase
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.
d. increases with pressure.
