Section 7 Flashcards
Cocks are used to control
a. water
b. any liquid
c. solids
d. none of these
b. any liquid
The dimension of surface tension is
a. ML^-2
b. MT^-2
c. MLT^-2
d. ML^-2 T
b. MT^-2
Pick out the correct statement.
a. Fanning friction factor is inversely proportional to Reynolds number
always.
b. The property of a randomly packed bed (with raschig rings) is given by the ratio of the total volume to the volume of voids in the bed.
c. Mach number in an incompressible fluid is always unity.
d. Mach number is given by the ratio of the speed of the fluid to
that of sound in the fluid under conditions of flow.
d. Mach number is given by the ratio of the speed of the fluid to
that of sound in the fluid under conditions of flow.
The friction factor is
a. always inversely proportional to the Reynolds number. b. not dimensionless.
c. not dependent on the roughness of the pipe.
d. none of these
d. none of these
Rubber latex is an example of a __________ .fluid.
a. pseudoplastic
b. bingham plastic
c. dilatent
d. Newtonion
a. pseudoplastic
Which of the following factors does not contribute to the pressure drop in a pipeline ?
a. Velocity of fluid
b. Size of pipe
c. Length of pipe and number of bends
d. None of these
d. None of these
The phenomenon occuring during pumping of a liquid solution containing dissolved gases, which may come out of the solution giving rise to gas pockets, is termed as
a. evaporation
b. cavitation
c. sublimation
d. stripping
b. cavitation
Working of a __________ pump characterises mixed flow.
a. turbine
b. piston
c. diaphragm
d. none of these
a. turbine
The rate of change of moment of momentum represents the ____ by the liquid
a. torque applied
b. force exerted
c. work done
d. power developed
a. torque applied
Cdfor the orifice plate varies from
a. 0.58 to 0.8
b. 0.93 to 0.98
c. 0.2 to 0.3
d. 0.02 to 0.03
a. 0.58 to 0.8
The discharge through a V-notch weir varies as
a. H^3/2
b. H^1/2
c. H^5/2
d. H^2/3
c. H^5/2
Water flow rate in a pipe of 3.5 metres diameter can be most economically and conveniently measured by a/an
a. pitot tube
b. venturimeter
c. orificemeter
d. rotameter
a. pitot tube
The specific speed of a pump is defined as the speed of a unit of such a size, that it
a. delivers unit discharge at unit head.
b. requires unit power for unit head.
c. delivers unit discharge at unit power.
d. none of these.
a. delivers unit discharge at unit head.
In case of venturimeters, friction losses are about __________ percent of maximum velocity head.
a. 2
b. 8
c. 12
d. 20
a. 2
With increase in the schedule number of a pipe of a particular nominal size, the
a. wall thickness also increases.
b. I.D. of the pipe decreases.
c. O.D. of the pipe remains constant.
d. all (a), (b) and (c)
d. all (a), (b) and (c)
Turbine impeller
a. produces only radial current.
b. produces only tangential current.
c. is effective over wide range of viscosities.
d. does not produce tangential current.
c. is effective over wide range of viscosities.
Friction produced by the formation of wakes is called the __________
friction.
a. disk
b. skin
c. form
d. none of these
c. form
Various efficiencies of a centrifugal pump are related as (where, ηm = mechanical efficiency ηv = volumetric efficiency. ηma = manometric efficiency ηo = overall efficiency)
a. ηma xηm xηv =ηo
b. ηm = ηv . ηma
c. ηma =ηm xηv
d. ηv =ηm xηma
b. ηm = ηv . ηma
When the pipe Reynold’s number is 6000, the flow is generally
a. viscous
b. laminar
c. turbulent
d. transition
c. turbulent
With a constant diameter impeller of a centrifugal pump
a. its capacity varies directly as the square of speed.
b. head varies as the square of speed.
c. horsepower input varies as the square of speed.
d. head varies as the speed.
b. head varies as the square of speed.
For water, when the pressure increases, the viscosity
a. also increases
b. decreases
c. remains constant
d. first decreases, and then increases
d. first decreases, and then increases
Location of vena-contracta in an orificemeter does not depend upon the
a. type of orifice.
b. density, viscosity & compressibility of the fluid.
c. ratio of pipe diameter to orifice diameter.
d. pipe roughness.
a. type of orifice.
At low Reynolds number
a. viscous forces are unimportant.
b. viscous forces control.
c. viscous forces control and inertial forces are unimportant.
d. gravity forces control.
c. viscous forces control and inertial forces are unimportant.
In Newton’s law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass varies as the __________ of its diameter.
a. inverse
b. square root
c. second power
d. first power
b. square root
Unsteady 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 increasing rate.
d. expanding tube at constant rate.
b. long pipe at decreasing rate.
Pick out the wrong statement pertaining to fluid flow.
a. The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
b. The Newtonion fluid velocity in a circular pipe flow is maximum at the centre of the pipe.
c. Navier-Stokes equation is applicable to the analysis of viscous flows.
d. Hagen-Poiseuille equation is applicable to the laminar flow of Newtonion fluids.
a. The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
A Newtonion liquid (ρ = density, μ = viscosity) is flowing with velocity v in a tube of diameter ‘D’. Let Δp be the pressure drop across the length ‘L’. For a laminar flow, Δp is proportional to
a. L ρv2/D
b. L μ;V/D2
c. D ρv^2/L
d. μ V/L
a. L ρv2/D
While starting a centrifugal pump, its delivery valve should be kept
a. opened.
b. closed.
c. either opened or closed ; it does not make any difference.
d. either opened or closed; depending on the fluid viscosity.
b. closed.
For flow past a flat plate, if x is the distance along the plate in the direction of flow, the boundary layer thickness is proportional to
a. sqrt(x)
b. 1/x
c. x
d. 1/x
a. sqrt(x)
Sewage sludge is an example of the __________ fluid.
a. Bingham plastic
b. Newtonion
c. pseudoplastic
d. dilatant
a. Bingham plastic
Multistage centrifugal pumps are generally used for
a. high head.
b. low head but high discharge.
c. highly viscous liquid.
d. slurries of high solid concentration.
a. high head.
The fluid jet discharging from a 2” diameter orifice has a diameter of 1.75” at its vena-contracta. The co-efficient of contraction is
a. 1.3
b. 0.766
c. 0.87
d. none of these
b. 0.766
A bed consists of particles of density 2000 kg/m^3. If the height of the bed is 1.5 metres and its porosity 0.6, the pressure drop required to fluidise the bed by air is
a. 25.61 kPa
b. 11.77 kPa
c. 14.86 kPa
d. 21.13 kPa
b. 11.77 kPa
Cavitation in a pump creates so many undesirable effects. Out of the following, which is not an undesirable effect created by cavitation ?
a. Decrease in effect
b. Increase in thrust
c. Develops noise
d. Develops high pressure
d. Develops high pressure
For a specific centrifugal air blower operating at constant speed & capacity, the power requirement and pressure vary
a. directly as square of gas density.
b. directly as gas density.
c. directly as square root of gas density.
d. inversely as gas density.
b. directly as gas density.
Capillary tube method of viscosity measurement is based on the
a. Hagen-Poiseulle’s equation
b. Stoke’s law
c. Navier-stokes equation
d. none of these
a. Hagen-Poiseulle’s equation
It is possible to integrate an automatic flow controller to a
a. flow nozzle
b. venturimeter
c. rotameter
d. none of these
c. rotameter
For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is
a. more
b. less
c. equal
d. independent of porosity
b. less
For a reciprocating pump, the indicator diagram is the graph between the
a.discharge and overall efficiency.
b. volume swept by piston for one complete revolution and the pressure in the cylinder.
c. angle swept by the crank pin at any instant and the discharge.
d. none of these.
b. volume swept by piston for one complete revolution and the pressure in the cylinder.
High specific speed of a pump implies that, it is a/an __________ pump.
a. centrifugal
b. mixed flow
c. axial flow
d. none of these
c. axial flow
A gas (density = 1.5 kg/m^3 , viscosity = 2x 10^-5 kg/m.s) flowing through a packed bed (particle size = 0.5 cm, porosity = 0.5) at a superficial velocity of 2 m/s causes a pressure drop of 8400 Pa/m. The pressure drop for another gas, with density of 1.5kg/m^3 and viscosity of 3 x 10^-5 kg/m.s flowing at 3 m/s will be
a. 8400 Pa/m
b. 12600 Pa/m
c. 18900 Pa/m
d. 16800 Pa/m
b. 12600 Pa/m
