Fluid Mechanics Part 4 Flashcards
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.
10
100
1000
10000
100
Choose the set of pressure intensities that are equivalent.
4.33 psi, 10 ft. of water, 8.83 inches of Hg.
4.33 psi, 10 ft. of water, 20.7 inches of Hg.
10 psi, 19.7 ft. of water, 23.3 inches of Hg.
10 psi, 19.7 ft. of water, 5.3 inches of Hg.
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.
It is a line across which there is no flow and it is equivalent to a rigid boundary.
Streamlines intersect at isolated point of zero velocity and infintie velocity.
The fluid lying between any two streamlines can be considered to be in isolation and the streamline spacing varies inversely as the velocity.
It is always parallel to the main direction of the fluid flow.
The most serious disadvantage of an orificemeter is that
it is not very accurate.
it is very costly.
most of the pressure drop is not recoverable.
it is not suitable for measuring gas flow.
most of the pressure drop is not recoverable.
The discharge through a rectangular weir varies as
H^1/2
H^5/2
H^2/5
H^3/2
H^3/2
In case of supersonic flow of a fluid through pipeline, the ‘Mach number’ is
0
1
< 1
> 1
> 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
2
4
1
0.5
Transition length for turbulent flow in smooth pipe is equal to __________ times the pipe diameter.
0.5
5
50
100
50
Disc compensators are provided in large diameter fuel gas carrying pipelines to
keep the pipe in proper orientation.
make the pipe joint leak-proof.
account for contraction/expansion of pipe due to temperature changes of the surroundings.
account for the pressure variation side the pipeline.
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.
7.65
32.36
48.22
125.6
125.6
Paper pulp is an example of __________ fluid.
dilatant
bingham plastic
Newtonion
pseudoplastic
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
0.1
0.55
0.95
1.85
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 . Vg
ρL . A.Hg
ρL . Vg/2
ρL .Vg/3
ρL . A.Hg
A relief valve
provides back pressure for a cylinder.
unloads a pump.
is a directional control valve.
none of these.
is a directional control valve.
An isentropic process is the one, in which
pv = constant
pvr = constant
pvr = constant, and process is reversible
none of these
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 turbulent flow only.
linear with radius for laminar flow only.
linear with radius for both laminar & turbulent flow.
parabolic with radius for both laminar & turbulent flow.
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
less
equal
more or less, depending on the type of particle
more
Specific speed of a centrifugal pump relates it with another pump having the
dynamic similarity
same efficiency
same speed
geometrical similarity
dynamic similarity
Air vessel fitted to a reciprocating pump
increases the work done.
decreases the work done.
causes cavitation.
results in non-uniform discharge.
decreases the work done.
Deformation drag, which is caused by widespread deformation of fluid around the immersed body
occurs when NRe is very small.
is primarily a friction drag.
is independent of body length.
depends mainly on cross-sectional shape.
occurs when NRe is very small.
In isotropic turbulence, the __________ are equal to each other.
temporal velocity components
mean square of velocity fluctuations in the three co-ordinate directions
root mean square of velocity fluctuations in the three co-ordinate directions
none of these
mean square of velocity fluctuations in the three co-ordinate directions
Viscosity of water is about __________ times that of air at room temperature.
15
55
155
1050
55
Net positive suction head (NPSH) of a centrifugal pump must be
greater than the vapour pressure of the liquid.
less than the vapour pressure of the liquid.
equal to the vapour pressure of the liquid.
less than barometric pressure.
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
specific gravity & temperature of the liquid.
leakage & pressure decreasing at higher elevations.
frictional resistance through pipes, fittings & passages.
all of these
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?
Discharge of water by a centrifugal pump being run at a constant rpm.
Water flow in the suction and discharge pipe of a reciprocating pump.
Water discharge from a vertical vessel in which constant level is maintained.
Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe.
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
laminar
unsteady
steady
uniform
unsteady
The __________ pressure is measured by a static tube.
dynamic
static
total
none of these
static
The speed of a sound wave in a gas is analogous to the speed of
an elementary wave in an open channel.
flow in an open channel.
a disturbance travelling upstream in moving fluid.
none of these.
an elementary wave in an open channel.
Mercury is an ideal barometric fluid mainly due to its
high density.
low compressibility.
low capillary action.
very low vapor pressure.
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 ?
Inertial and drag forces are important.
Drag, gravitational and buoyancy forces are impportant.
Drag force and gravitational forces are important.
None of the above.
Drag, gravitational and buoyancy forces are impportant.
A gas
signifies absence of density.
can resist shearing action.
is incompressible.
is a supercritical vapor.
is a supercritical vapor.
Pitot tube measures the __________ of a fluid.
pressure
average velocity
average flow rate
point velocity
point velocity
Which of the following is not dimension-less?
Froude number
Kinematic viscosity
Pressure co-efficient
None of these
Kinematic viscosity
In laminar flow through a round tube, the discharge varies
linearly as the viscosity.
inversely as the pressure drop.
inversely as the viscosity.
as the square of the radius.
inversely as the viscosity.
Which is not a variable head meter ?
Venturimeter
Pitot tube
Rotameter
None of these
Rotameter
The pipe wall thickness is minimum for a pipe of given nominal size having schedule number
160
120
80
40
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
2000
10
100
1000
1000
Centrifugal pumps as compared to reciprocating pumps
run at a lower speed for the same discharge.
do not need priming.
deliver fluid with pulsating/fluctuating discharge.
can be run with discharge line valve closed for a short interval.
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 ?
Rotation
Translation
Linear deformation
Angular deformation
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 ?
Rotational
Unsteady
Turbulent
Non-uniform
Non-uniform
The continuity equation in ideal fluid flow states that
net rate of inflow into any small volume must be zero.
energy is not constant along a streamline.
energy is constant along a streamline.
there exists a velocity potential.
net rate of inflow into any small volume must be zero.
Bernoulli’s equation is not applicable, when the flow is
irrotational.
incompressible.
viscous.
all of these.
all of these.
The equivalent diameter for pressure drop calculation for a duct of square cross-section is given by(where, x = each side of the square duct)
x
√πx
√2x
x
Centre of pressure of a plane surface of arbitrary shape immersed vertically in a static mass of fluid
lies above the centroid of the plane surface.
is independent of the specific weight of the fluid.
is different for different fluids.
is at the centroid of the plane surface.
is independent of the specific weight of the fluid.
Drag co-efficient for flow past immersed body is the ratio of __________ to the product of velocity head and density.
shear stress
shear force
average drag per unit projected area
none of these
average drag per unit projected area
Creeping flow around a sphere is defined, when particle Reynolds number is
< 2100
< 0.1
> 2.5
< 500
< 0.1
< 0.1 creeping
Open channel liquid flow is most conveniently measured by a
hot wire anemometer
notch
rotameter
segmental orifice
notch
Toothpaste is a
Bingham plastic
pseudoplastic
Newtonion liquid
dilatent
dilatent
Slurries can be most conveniently pumped by a __________ pump.
screw
reciprocating
gear
centrifugal
centrifugal
Volute type of casing is provided in a centrifugal pump to
convert velocity head to pressure head.
convert pressure head to velocity head,
reduce the discharge fluctuation.
increase the discharge.
increase the discharge.
Each term of the Bernoulli’s equation written in the form, (1) , represents the total energy per unit
mass
volume
specific weight
none of these
mass
In a free vortex, the
velocity changes linearly with radial distance.
flow is necessarily rotational.
radial component of velocity is same everywhere.
stream lines are not circular.
velocity changes linearly with radial distance.
Pick out the wrong statement.
The eddy viscosity is a function of the type of turbulence involved.
The eddy viscosity is a fluid property.
The viscosity of gas increases with increase in temperature.
The viscosity of a liquid increases with decrease in temperature.
The eddy viscosity is a fluid property.
The velocity distribution in direction normal to the direction of flow in plane Poiseuille flow is
hyperbolic
parabolic
linear
none of these
parabolic
In fluid flow, the stagnation point is defined as a point, where the __________ is zero.
flow velocity
pressure
total energy
all of these
flow velocity
A special type of liquid transporting device is the diffuser pump, in which __________ are minimised.
bearing losses
disk friction
shock losses
cavitation
shock losses
diffuser - shock
Which of the following is most prone to pulsating discharge flow ?
Centrifugal pump
Reciprocating pump
Gear pump
Axial flow pump
Gear pump
A streamline is
the line connecting the mid-points of flow cross-sections.
defined for uniform flow only.
drawn normal to the velocity vector at every point.
always the path of a particle.
drawn normal to the velocity vector at every point.
Which of the following relationship is valid for the equilibrium position of the float in a rotameter ?(where, Df= Drag force on the float Bf = Buoyant force on the float Wf = Weight of the float)
Df + Bf = Wf
Df = Bf + Wf
Df + Bf + Wf =0
none of these
Df + Bf = Wf
Drag is defined as the force exerted by the
fluid on the solid in a direction opposite to flow.
fluid on the solid in the direction of flow.
solid on the fluid.
none of these.
fluid on the solid in the direction of flow.
The boundary layer is that part of a moving fluid, in which the fluid velocity is
affected by the fluid flow pressure.
constant.
affected by the presence of a solid boundary.
all of these
affected by the presence of a solid boundary.
The terminal velocity of a solid spherical particle falling through a stationary fluid mass in the Stoke’s law range is proportional to the
inverse of fluid viscosity.
square of particle size.
difference in the densities of the particle & fluid.
all of these
all of these
Which of the following equations as suggested by Colebrook and White gives the increase in roughness of a new surface (E0) with age/time (t) (where, E = roughness of the surface after time’t’. o = a co-efficient to be experimentally determined)?
E = E0 + o.t
E = E0 + o.t^2
E = E0 + o.t^3
E = E0 + o.t^4
E = E0 + o.t
Nominal size of a pipe is an indication of its __________ diameter.
inner
outer
approximate
none of these
approximate
Fluidised beds are formed, when the
fluid friction is zero
gravity force is less than the fluid friction.
pressure forces equal gravity forces.
sum of the fluid friction and pressure forces is equal and opposite to gravity forces.
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.
1
20363
5.5
20090
1
Pick out the wrong statement:
The vacuum pressure is always the negative gauge pressure.
The pressure of the liquid measured by a piezometer tube is the gauge pressure.
Manometric liquid should have high surface tension.
The point at which the resultant pressure on an immersed surface acts, is known as the centre of gravity.
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.
vane
piston
centrifugal
plunger
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
d
d^2
d^2.5
d^4
d^2.5
Pump used for the transportation of molten sodium in a fast breader reactor is a/an __________ pump.
reciprocating
plunger
electromagnetic
gear
electromagnetic
Small pressure differences in liquids is measured using a/an
U-tube manometer.
inclined tube manometer.
pitot tube.
none of these.
inclined tube manometer.
With increase in pump speed, its NPSH requirement
decreases
increases
remains unaltered
can either increase or decrease ; depends on other factors
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.
directly proportional to
inversely proportional to
inversely proportional to the square root of
independent of
inversely proportional to
Gear pump
is a positive displacement pump.
is a centrifugal pump.
is a non-positive displacement pump.
can be started with delivery valve closed.
is a positive displacement pump.
Most of the centrifugal pumps used in chemical plants are usually __________ driven.
steam
diesel engine
electric motor
gas turbine
electric motor
Check valve provided in the discharge line of a centrifugal pump serves the purpose of controlling the
back flow of fluid in the event of stoppage of pump.
discharge pressure.
flow of liquid during operation of the pump.
all of these
back flow of fluid in the event of stoppage of pump.
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
weir
hot wire anemometer
cup and vane aneometer
none of these
hot wire anemometer
The time taken for gravity flow of a fixed volume of liquid (as in Redwood viscometer) is directly proportional to its
absolute viscosity.
ratio of absolute viscosity to density.
density.
Reynolds number.
ratio of absolute viscosity to density.
Sewage sludge is __________ type of non-Newtonion fluid.
dilatant
Bingham plastic
Pseudo plastic
none of these
Bingham plastic
Ratio of pressure and inertia force gives __________ number.
Weber
Mach
Euler
Froude
Euler
ME Mach - inertial to Elastic
WS Weber - inertial to Surface tension
FG Froude - inertial to Gravitational
RV Reynold - inertial to Viscous
EP Euler - Pressure to inertial
Permanent loss in a venturimeter is about __________ percent of the pressure drop in theupstream cone.
1
10 .
40
70
10 .
Volume of liquid displaced by a floating body is equivalent to its
own weight
submerged weight
own volume
submerged volume
own weight
The __________ is measured by a piezometric opening.
dynamic pressure
static pressure
total pressure
point velocity
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 ?
Penstock
Siphon
Tunnel
Pressure pipeline
Siphon
Steady uniform flow is represented by flow through a/an
long pipe at constant rate.
long pipe at decreasing rate.
expanding tube at constant rate.
none of these.
long pipe at constant rate.
Pick out the correct statement pertaining to the flow through a converging-diverging tube.
The value of Mach number is always unity at the throat.
No shock wave develops in the tube when the Mach number at exit is greater than unity.
Throughout the converging portion of the tube, the density increases in the downstream direction.
none of these.
No shock wave develops in the tube when the Mach number at exit is greater than unity.
Cavitation can be prevented by
suitably designing the pump.
maintaining the suction head sufficiently greater than the vapour pressure.
maintaining suction head = developed head.
maintaining suction head lower than the vapour pressure.
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
increase
decrease
remain same
be quadrupled
increase
Steady flow occurs, when the
conditions change steadily with time.
conditions are the same at the adjacent points at any instant.
conditions do not change with time at any point.
rate of the velocity change is constant.
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
increases
decreases
remains unchanged
increases exponentially
decreases
Which of the following two quantities when same, makes one pipe system equivalent to another pipe system ?
Head & discharge
Length & discharge
Length & diameter
Friction factor & diameter.
Head & discharge
The kinetic energy correction factor for velocity distribution of laminar flow is
0.5
1.66
1
2
1.66
Priming of a centrifugal pump is done to
increase the mass flow rate of fluid.
develop effective pressure rise by the pump.
avoid chances of separation inside the impeller.
none of these.
avoid chances of separation inside the impeller.
Bed pressure drop in an air fluidised bed of catalyst particles (rho-p = 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
90
60
45
30
60
For pipes that must be broken at intervals for maintenance, the connector used should be a/an
union
tee
reducer
elbow
union
A fluid is the one, which
cannot remain at rest under the action of shear force.
continuously expands till it fills any container.
is incompressible.
permanently resists distortion.
cannot remain at rest under the action of shear force.
A fluid (1) is moving at critical flow condition (NRe = 2100) through a pipe of dia 3 cms. Velocity of flow is __________ cm/sec.
7
700
7000
630
7
Capillary rise of mercury in a small diameter tube is proportional to (where, d = diameter of the tube, σ = surface tension of mercury)
d
1/d
σ
l/σ
σ
The pressure drop per unit length of pipe incurred by a fluid ‘X’ flowing through pipe is delta-p. 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
Δp
2Δp
Δp²
Δp/2
2Δp
Fluid flow in a/an __________ is an example of pressure flow.
partially filled pipeline
pipe
open channel
river.
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).
Re
√Re
1/Re
Re^-1/2
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
26
42
269
325
269
A 0.5 m high bed made up of a 1 mm dia glass sphere (density 2500 kg/m^3 ) is to be fluidised by water (density 1000 kg/m^3 ). If at the point of incipient fluidisation, the bed voidage is 40%, the pressure drop across the bed is
4.4 KPa
2.94 KPa
3.7 KPa
none of these
4.4 KPa
Select the wrong statement pertaining to flow of an incompressible fluid through a venturimeter.
For frictionless flow, the fluid pressure entering the venturi meter will be exactly equal to that leaving the venturimeter.
Discharge of fluid through a venturimeter depends upon the gage difference irrespective of the orientation of venturimeter.
Venturimeter occupies less space than an orificemeter.
Venturimeter incurs less power loss compared to an equivalent orificemeter.
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
increase
decrease
remain same
data insufficient to predict pressure drop
increase
The bulk modulus of elasticity of a liquid
is zero for incompressible liquid.
decreases with pressure.
is independent of temperature & pressure.
increases with pressure.
increases with pressure.
Curve III in the above diagram represents a/an
dilatent fluid
pseudo plastic fluid
ideal plastic
none of these
pseudo plastic fluid
What is the ratio of total kinetic energy of fluid passing per second to the value obtained on the basis of average velocity (for laminar flow through a circular pipe)?
0.5
1
1.5
2
2
The line traced by a single fluid particle as it moves over a period of time is called __________ line.
stream
path
equipotential
none of these
path
A stream tube is that, which has __________ cross-section entirely bounded by stream lines.
a circular
any convenient
a small
a large
any convenient
Colebrook equation for friction factor in turbulent flow is given by, (1) . It reduces to Nikuradse equation for a value of (1) equal to
0
1
infinite
0.5
1
The unit of velocity head is
ft-lb/sec
ft-lb/ft^3
ft-lbf/lb
ft-lbf/sec.
ft-lbf/lb
Which of the following properties of a fluid is responsible for offering resistance to shear ?
Surface tension.
Viscosity.
Specific gravity.
all of these
Viscosity.
Erosion and pits formation on the impeller of a centrifugal pump may be due to
cavitation.
low speed of impeller.
its operation with delivery valve closed for considerable time after starting the pump.
off centering of pump with motor.
cavitation.
The velocity profile exhibited by laminar flow of Newtonion fluids is such that the velocity distribution w.r.t. radius of the circular pipe is a/an __________ with the apex at the centre line of the pipe.
hyperbola
parabola
semi-circle
semi-ellipse
parabola
The excess of the sum of pressure & velocity heads over the vapor pressure of the liquid at the suction is called the
static submergence.
net positive suction head (NPSH).
cavitation sensitivity.
priming.
net positive suction head (NPSH).
Piezometric head is the sum of the __________ heads.
elevation & kinetic energy
elevation & pressure
kinetic energy & pressure
none of these
elevation & pressure
Propellers are
axial flow mixers.
low speed impeller.
used for mixingliquids of high viscosity.
radial flow mixers.
axial flow mixers.
Which of the following is not an advantage of fluidisation from transfer operation point of view?
Intimate contact of the fluid with all parts of the solid particles.
Lower fluid pumping power requirement.
Minimisation of temperature variation.
Prevention of particle seggregation.
Lower fluid pumping power requirement.
Upto what value of ‘Mach number’, a fluid may be considered as incompressible ?
0.03
0.3
3
10
0.3
The head developed by a centrifugal pump is largely determined by the
power of the pump.
nature of the liquid being pumped.
angle of the vanes and the speed of the tip of the impeller.
vapour pressure of the liquid.
angle of the vanes and the speed of the tip of the impeller.
Pick out the wrong statement:
Greater is the kinematic viscosity of the liquid, greater is the thickness of the boundary layer.
Blowers develop a maximum pressure of 2 atmospheres.
Friction losses in pipe fittings are generally expressed in terms of velocity heads.
Fanning friction factor in case of turbulent flow of liquids in pipe depends upon relative roughness & Reynolds number.
Friction losses in pipe fittings are generally expressed in terms of velocity heads.
Flow rate of high velocity flue gas discharged through a stack to the atmosphere can be most conveniently measured by a
pitot tube
manometer
rotameter
none of these
pitot tube
Potential flow is the flow of
compressible fluids with shear.
compressible fluids with no shear.
incompressible fluids with shear.
incompressible fluids with no shear.
incompressible fluids with no shear.
The value of critical Reynolds number for pipe flow is
1300
10000
100,s000
none of these.
1300
Mach number is important in a fluid flow problem, when the inertia and __________ forces predominate.
elastic
viscous
gravity
none of these
elastic
Fanning friction factor is equal to(where, fB = Blassius friction factor).
fB/4
fB/2
4fB
2fB
fB/4
In case of coutte flow, the fluid flow is between two large flat parallel plates with
top plate moving and the bottom plate fixed.
bottom plate moving and the top plate fixed.
both the plates fixed.
both the plates moving.
top plate moving and the bottom plate fixed.
In a stabilised soap bubble, pressure inside it compared to external pressure is
more
less
same
unpredictable
more
The component of acceleration resulting due to unsteady nature of flow is called __________ acceleration.
normal
local
convective
tangential
local
Power required for mixing Newtonion fluids is a function of the
speed of impeller, diameter of impeller & viscosity.
density & viscosity of fluid only.
density of fluid, viscosity of fluid & impeller dia only.
none of these.
none of these.
Multistage compressors are used in industry, because they
reduce the cost of compressor.
reduce the size requirement,
resemble closely to isothermal compression.
are easy to control.
resemble closely to isothermal compression.
The hydrodynamic and thermal boundary layers will merge, when
Prandtl number is one.
Schmidt number tends to infinity.
Nusselt number tends to infinity.
Archimedes number is greater than 10000.
Prandtl number is one.
Differential manometer measures the
atmospheric pressure.
sub-atmospheric pressure.
pressure difference between two points.
none of these.
pressure difference between two points.
For a stable equilibrium of a submerged body (where, G and B are centres of gravity & buoyancy respectively).
G is above B
B is above G
B & coincide
none of these
B is above G
With increase in the ratio of orifice diameter to pipe diameter in case of an orificemeter, the overall pressure loss
decreases
increases
remains constant
increases linearly
remains constant
The vent valve provided in a liquid handling centrifugal pump is
generally a needle valve.
used to release any gases that might be vapour locking the pump.
helpful in easy removal of samples.
all (a), and (b) and (c).
all (a), and (b) and (c).
The discharge through a semi-circular weir varies as (where, H = Head of liquid.)
H
H^2
H^3/2
H^1/2
H^2
The Mach number for hypersonic flow of compressible fluid is
1
> 1
> 4
< 2
> 4
Boundary layer thickness in turbulent flow over a flat plate increases as (where, d = distance from the leading edge.)
√d
d^2/3
d^4/5
d^1/3
d^4/5
The valve used for very remote and accurate control of fluid is a __________ valve.
needle
globe
gate
butterfly
needle
f = 16/NRe, is valid for
turbulent flow
laminar flow through an open channel
steady flow
none of these
none of these
A mixed flow centrifugal pump
employs such an impeller, through which the flow is a combination of radial & axial flow.
mixes the two fluids before pumping them.
pumps the two fluids separately and then mixes them.
employs impellers in both the radial & axial directions.
employs such an impeller, through which the flow is a combination of radial & axial flow.
In centrifugal pump operation, the cavitation can be eliminated by maintaining suction pressure __________ the vapor pressure of the liquid at the suction temperature.
lower than
higher than
equal to
none of these
higher than
A rectangular surface 3’ x 4’, has the lower 3 edge horizontal and 6’ below a free oil surface (sp. gr. 0.8). The surface inclination is 300 with the horizontal. The force on one side of the surface is(where, y = specific weight of water)
39.6y
48y
49.2y
58y
48y
A bed of spherical particles (specific gravity 2.5) of uniform size 1500 um is 0.5 m in diameter and 0.5 m high. In packed bed state, the porosity may be taken as 0.4. Ergun’s equation for the above fluid-particle system (in SI units) is given below : delta- P/L = 375 x 10^3 VOM + 10.94 x 10^6 V^2OM (SI units) If water is to be used as the fluidising medium, the minimum fluidisation velocity, VOM is
12 mm/s
16 mm/s
24 mm/s
28 mm/s
16 mm/s
One dimensional flow implies
flow in a straight line.
steady uniform flow.
unsteady uniform flow.
a flow which does not account for changes in transverse direction.
a flow which does not account for changes in transverse direction.
one dimensional - does not… transverse
In case of turbulent flow of a Newtonion fluid in a straight pipe, the maximum velocity is equal to (where, Vavg = average fluid velocity)
Vavg
1.2 Vavg
1.5 Vavg
1.8 Vavg
1.2 Vavg
Centrifugal compressors compared to reciprocating compressors
require less space.
have quieter operation.
have lower operating costs.
all of these
all of these
For laminar flow of Newtonion fluids through a circular pipe, for a given pressure drop and length & diameter of pipe, the velocity of fluid is proportional to(where, u = fluid viscosity )
u
1/u
sqrt-u
1/sqrt-u
1/u
Umf is the minimum fluidisation velocity for a bed of particles. An increase in the superficial gas velocity from 2 Umf to 2.5 Umf results in (all velocities are smaller than the entrainment velocity of the particles) no change in the
drag on particles
drag on coloumn walls
bed height
bed voidage
bed height
Stoke’s law is valid, when the particle Reynolds number is
< 1
> 1
< 5
none of these
< 1
Which of the following is not a dimension-less parameter ?
Pressure-co-efficient
Froude number
Kinematic viscosity
Weber number
Kinematic viscosity
In which of the following cases, it is possible for flow to occur from low pressure to high pressure ?
Flow of liquid upward in a vertical pipe.
Flow through a converging section.
Flow of air downward in a pipe.
Impossible in a constant cross-section conduit.
Flow through a converging section.
The blades of a centrifugal impeller are said to be curved forward, if the __________ of the motion of impeller blades.
inlet tip of a blade curves in a direction opposite to that
outlet tip of a blade curves in a direction opposite to that
inlet tip of a blade is towards the direction
outlet tip of a blade is towards the direction
outlet tip of a blade is towards the direction
For the same terminal conditions and fitting size, the least friction loss is incurred in a/an
T-joint
union
45 elbow
90 bend
union
A floating/submerged body is always stable, if its centre of gravity
lies above its centre of buoyancy.
and centre of buoyancy coincide.
lies below its centre of buoyancy.
lies above its meta centre.
lies below its centre of buoyancy.
Critical velocity in a pipe flow
increases as fluid viscosity increases.
increases as pipe diameter increases.
independent of fluid density.
none of these.
increases as pipe diameter increases.
A centrifugal pump designed to pump water is employed to pump a more viscous oil. In the later case, the pump
develops a lower head.
capacity is reduced.
requires more power.
all of these
all of these
In an incompressible flow of fluid, the fluid
temperature remains constant.
compressibility is greater than zero.
density does not change with pressure & temperature.
is frictionless.
density does not change with pressure & temperature.
The ratio of maximum to average velocity in case of streamline flow between parallel plates is
1
1.5
2
2.5
1.5
A weir is used to measure the large water discharge rate from a river or from an open channel. A weir is not of __________ shape.
circular
rectangular
triangular
trapezoidal
circular
Pressure co-efficient is the ratio of pressure forces to __________ forces.
gravity
inertial
viscous
none of these
inertial
Which of the following conditions must be satisfied for lift force to be developed ?
The body should be bluff body.
The body should be stream lined.
Circulation around the body is essentially required.
The main stream velocity must approach the velocity of sound in that fluid medium.
Circulation around the body is essentially required.
The Reynolds number for an ideal fluid flow is
4
2100-4000
4000
∞
∞
