Momentum Transfer (Set 2) Flashcards
As one of the transport phenomena, the concepts in momentum transfer (also known as fluid mechanics) are crucial for the design, operation, and maintenance of fluid flow equipment such as pipes, pumps/compressors, turbines/expanders, agitators, and metering devices.
For the production of very high vacuum, a ____ pump is normally used.
diffusion
In parallel pipe problems, the
head loss is the same through each pipe.
Fluid flow through a packed bed is represented by the ____ equation.
Ergun’s
____ is an example of axial flow impeller.
Propeller
Froude number is not a factor
when there is no vortex formation.
If three pipes of different diameters, lengths & friction factors are connected in parallel, then (where, Q = flow rate, V= fluid velocity f = friction factor).
Q = Q1 + Q2 + Q3
Horsepower requirement for given pump capacity depends upon the
all of these
Bernoulli’s equation accounts for the
different forms of mechanical energy
____ pumps are a group of vacuum pumps.
Hyter
Plunger pumps are used for
higher pressure
What is the ratio of displacement thickness to nominal thickness for a linear distribution of velocity in the boundary layer on a flat plate ?
0.5
In turbulent flow, the
shear stresses are generally larger than in a similar laminar flow.
Momentum correction factor used in fluid flow problems accounts for the
non uniform direction of velocities at inlet & outlet sections.
Design of the casing of centrifugal pump should be such as to minimise the
loss of kinetic head
Which of the following is used for pumping crude oil from oil well ?
Duplex/triplex reciprocating pump
The energy loss in flow through ven-turimeter is less than that through flow nozzle, because in case of a flow nozzle, the
sudden expansion of flow in the downstream occurs.
____ flow means the flow of incompressible fluid with no shear.
Potential
The continuity equation
relates mass flow rate along a stream tube.
The energy loss over a length of pipeline according to Darcy-Weisbach equation for pipe flow is…..the mean velocity of flow.
directly proportional to square of
Pressure drop in a packed bed for laminar flow is given by the ____ equation.
Kozney-Karman
The fluid velocity varies as the cube of the cylinderical pipe diameter in case of steady state laminar flow at constant pressure drop for ____ fluid.
pseudoplastic
Stoke’s law is valid, when NRe, p is less than
2
Froude number is the ratio of
inertial stress to gravitational stress.
Normal depth in open channel flow is the depth of flow in the channel
corresponding to uniform flow.
Which of the following flow measuring devices is an area meter ?
Rotameter
With decrease in particle size to be fluidised by a particular fluid, the operating range of fluidisation velocity
does not change
Diaphragm valves are used for handling ____ fluids.
corrosive
The schedule number of a pipe is an indication of its
wall thickness
Minimum porosity for fluidisation is
the porosity of the bed when true fluidisation begins.
A centrifugal pump used to pump water is used to pump an oil with specific gravity of 0.8 at the same rate. The power consumption will now
decrease
Steady non-uniform flow is exemplified by flow through a/an
expanding tube at constant rate.
The maximum depth from which a centrifugal pump can draw water is
34 feet.
Hot wire anemometer is used to measure the
velocity of gases.
Propeller type centrifugal pumps are most suitable for
high capacity at low heads.
The fluid velocity varies as the square of the cylindrical pipe diameter, in case of steady state laminar flow at constant pressure drop, for ____ fluid.
Newtonion
Momentum transfer in laminar flow of fluids results due to the
velocity gradient
The capillary rise of mercury is maximum in glass tube of dia ____ mm.
0.5
Diaphragm pumps are used to transport
slurries
For steady ideal fluid flow, the Bernoulli’s equation states that the
energy is constant along a stream line, but may vary across stream lines
In case of a centrifugal pump, the theoretical head developed is dependent on the ____ the impeller.
a. speed of
b. diameter of
c. fluid velocity leaving
all of these
A hydraulic press has a ram of 10 cms in diameter and a plunger of 1 cm in diameter. The force required on the plunger to raise a weight of 10 tons on the ram is ____ kg.
100
Choose the set of pressure intensities that are equivalent.
4.33 psi, 10 ft. of water, 8.83 inches of Hg.
Pick out the wrong statement about a streamline.
It is always parallel to the main direction of the fluid flow.
The most serious disadvantage of an orificemeter is that
most of the pressure drop is not recoverable.
The discharge through a rectangular weir varies as
H^3/2
In case of supersonic flow of a fluid through pipeline, the ‘Mach number’ is
> 1
A centrifugal pump has the following specifications: Power = 4 H.P.; Speed = 800 rpmHead = 8 metresFlow = 1000 litres/minutes.If its speed is halved, the power consumed now will be ____ hp.
0.5
Transition length for turbulent flow in smooth pipe is equal to ____ times the pipe diameter.
50
Disc compensators are provided in large diameter fuel gas carrying pipelines to
account for contraction/expansion of pipe due to temperature changes of the surroundings.
Discharge from a 24 inch pipe of water at 10 ft/sec will be ____ ft3/sec.
125.6
Paper pulp is an example of ____ fluid.
bingham plastic
The ratio of the depth of flow to the diameter of the channel for maximum discharge in a circular channel in open channel flow is
0.95
A conical tank with a bottom opening of cross-sectional area A is filled with water and is mounted on supports as shown in the figure. What is the force F with which plate X must be pushed up to prevent water from leaking ? Assume that the density of air is negligible as compared to the density of water ρL. (1)
ρL . A.Hg
A relief valve
is a directional control valve.
An isentropic process is the one, in which
pvr = constant, and process is reversible
The distribution of shear stress in a stream of fluid in a circular tube is
linear with radius for both laminar & turbulent flow.
For motion of spherical particles in a stationary fluid, the drag co-efficient in hindered settling compared to that in free settling is
more
Specific speed of a centrifugal pump relates it with another pump having the
dynamic similarity
Air vessel fitted to a reciprocating pump
decreases the work done.
Deformation drag, which is caused by widespread deformation of fluid around the immersed body
occurs when NRe is very small.
In isotropic turbulence, the ____ are equal to each other.
mean square of velocity fluctuations in the three co-ordinate directions
Viscosity of water is about ____ times that of air at room temperature.
55
Net positive suction head (NPSH) of a centrifugal pump must be
greater than the vapour pressure of the liquid.
Actual lift of a pump is always less than the theoretical lift and is limited by the
a. specific gravity & temperature of the liquid.
b. leakage & pressure decreasing at higher elevations.
c. frictional resistance through pipes, fittings & passages.
all of these
In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow?
Water flow in the suction and discharge pipe of a reciprocating pump.
Nature of fluid flow during the opening of a valve in a pipeline is
unsteady
The ____ pressure is measured by a static tube.
static
The speed of a sound wave in a gas is analogous to the speed of
an elementary wave in an open channel.
Mercury is an ideal barometric fluid mainly due to its
very low vapor pressure.
A spherical particle is falling slow in a viscous liquid such that Reynolds number is less than 1. Which statement is correct for this situation ?
Drag, gravitational and buoyancy forces are impportant.
A gas
is a supercritical vapor.
Pitot tube measures the ____ of a fluid.
point velocity
Which of the following is not dimension-less?
Kinematic viscosity
In laminar flow through a round tube, the discharge varies
inversely as the viscosity.
Which is not a variable head meter ?
Rotameter
The pipe wall thickness is minimum for a pipe of given nominal size having schedule number
40
Reynolds number for flow of water at room temperature through 2 cm dia pipe at an average velocity of 5 cm/sec is around
1000
Centrifugal pumps as compared to reciprocating pumps
can be run with discharge line valve closed for a short interval.
What type of motion the fluid element undergoes, when it changes from one position to another position, such that the angle between the two sides change ?
Angular deformation
In which type of fluid flow, the velocity of flow of fluid changes from point to point in the fluid at any instant ?
Non-uniform
The continuity equation in ideal fluid flow states that
net rate of inflow into any small volume must be zero.
Bernoulli’s equation is not applicable, when the flow is
a. irrotational.
b. incompressible.
c. viscous.
all of these.
