Fluid Mechanics Part 2 Flashcards
In Newton’s law range, the drag co-efficient for the motion of spherical particle in a stationary fluid is
0.44
0.044
4.4
44
0.44
A pressure of 10 m head of water is equivalent to __________ kN/m2.
98
147
196
49
98
A pressure head of 320 metres of water in meters of CCl4 (sp.gr = 1.6) will be
100
200
320
160
200
P1=P2
ρgh1=ρgh2
1x9.8x320=1.6x9.8xh2
h2=320/1.6=200
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
0.5
1
2
0.33
2
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.
logarithmic
linear
hyperbolic
parabolic
logarithmic
Maintenance cost of a __________ pump for a particular duty is the least.
centrifugal
reciprocating
volute
gear
centrifugal
Remember: centrifugal maintenance lowest
Choking in case of pipe flow means that a
specified mass flow rate can not be achieved.
valve is closed in the line.
restriction in flow cross-section area occurs.
none of these.
specified mass flow rate can not be achieved.
Velocity of liquid hydrocarbon fuels in a pipeline can not be measured by magnetic flowmeters, because their __________ is very low/small.
thermal conductivity
electrical conductivity
specific gravity
electrical resistivity
electrical conductivity
The nominal size of a hose pipe is specified by its
I.D.
O.D.
thickness
none of these
I.D.
Remember: nominal hose ID
Transition from laminar flow to turbulent flow is aided by the
surface roughness and curvature (i.e.sharp corners).
vibration.
pressure gradient and the compressibility of the flowing medium.
all of these.
all of these.
For flow of fluids through packed bed, the superficial velocity is
less than the average velocity through channels.
more than the average velocity through channels.
dependent on the pressure drop across the bed.
same as the average velocity through channels.
less than the average velocity through channels.
Cd is always __________ Cc.
greater than
less than
equal to
either more or less than
greater than
Buoyant force
for non-symmetrical bodies is not vertical.
depends on the depth of the submergence of the floating body.
depends on the weight of the floating body.
none of these.
depends on the weight of the floating body.
Which of the following is an undesirable property of a manometric liquid ?
Non-sticky & non-corrosive nature.
High vapour pressure.
Low viscosity & surface tension.
Low co-efficient of thermal expansion.
High vapour pressure.
Characteristic curves for a centrifugal pump plotted against its capacity is shown in the diagram. x, y and z denote respectively (1)
efficiency, head and B.H.P.
head, efficiency and B.H.P.
B.H.P., efficiency and head
efficiency, B.H.P. and head
head, efficiency and B.H.P.
Liquid delivery by centrifugal pump starts, only when the head developed by it is equal to the __________ head.
manometric
total
static
friction
manometric
The speed of sound in an ideal gas varies as the
temperature
pressure
density
none of these
temperature
The maximum head that can be developed by a single impeller is __________ ft.
25
100
250-300
1000
250-300
The ratio of hydrodynamic boundary layer to thermal boundary layer thickness in case of liquid metals is
< 1
1
> 1
2
< 1
The general relationship between speed N, head H, power P and discharge Q for a centrifugal pump is
Q ∝ N : H ∝ N^2 : P ∝ N^3
Q ∝ N^2 : H ∝ N^3 : P ∝ N
Q ∝ N : H ∝ N^3 : P ∝ N2
Q ∝ N^3 : H ∝ N : P ∝ N^2
Q ∝ N : H ∝ N^2 : P ∝ N^3
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 ?
0.5
0.67
1
2
2
Foot valve provided in the pump is a __________ valve.
direction control
back pressure
relief
pressure reduction
back pressure
The discharge co-efficient for an orificemeter does not depend upon the
pipe length.
ratio of pipe diameter to orifice diameter.
type of orifice & the Reynolds number.
pipe diameter.
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?
Increasing the impeller speed and the volute area.
Increasing the number of vanes in the impeller.
Mounting of two or more impellers in series on a single shaft.
Either of (a), (b) or (c).
Mounting of two or more impellers in series on a single shaft.
An equipotential line is __________ to the velocity vector at every point.
normal
abnormal
tangential
none of these
normal
Path followed by water jet issuing from the bottom of a water tank will be a
parabola (vertex being at the opening).
hyperbola.
horizontal straight line.
zig-zag path (which is geometrically undefined).
parabola (vertex being at the opening).
Which of the following produces maximum pressure difference for transportation of gases ?
Vaccum pumps
Blowers
Fans
Compressors
Compressors
For flow through a venturi at a particular discharge, the correct relationships among velocities at point X, Y and Z would be (1)
V1 < V2 < V3
V2 > V1 and V2 > V3
V1 > V2 > V3
none of these.
V2 > V1 and V2 > V3
Drag co-efficient in hindered settling is __________ that in free settling.
less than
equal to
not necessarily greater than
always greater than
always greater than
Efficiency of power transmission (n) through a circular pipe is given by (ht - hf)/ht, which has a maximum value of __________ percent.
1.3770833333333332
50
66.6
88.8
66.6
One dimensional fluid flow implies the
flow in straight lines only.
uniform flow.
steady uniform flow.
flow in which transverse components are zero.
flow in which transverse components are zero.
__________ forces act on a particle moving through a stationary fluid.
Gravity
Drag
Buoyant
all of these
all of these
In frictional fluid flow, the quantity, P/ρ + V²/2gc + gc/gz , is
constant along a streamline.
not constant along a streamline.
increased in the direction of flow.
none of these.
not constant along a streamline.
Hydraulic radius is the ratio of
wetted perimeter to flow area.
flow area to wetted perimeter.
flow area to square of wetted perimeter.
square root of flow area to wetted perimeter.
flow area to wetted perimeter.
The unit of bulk modulus of elasticity for a liquid in S.I. unit is
N
N/m
N/m^2
N/m^3
N/m^2
Power requirement of fans having constant wheel diameter varies __________ fan speed.
as square of
directly as
as cube of
none of these
as cube of
In the low Reynolds number region, the drag force on a sphere is proportional to
V
V^2
V^4
V^0.5
V
The continuity equation
is independent of the compressibility of the fluid.
is dependent upon the viscosity of the fluid.
represents the conservation of mass.
none of these.
represents the conservation of mass.
Experimental study of laminar fluid flow through a circular tube was conducted by
Reynolds
Hagen and Poiseuille
Pascal
Blake-Plummer
Hagen and Poiseuille
The most economical flow control valve for use with large diameter pipes is a
butterfly valve
globe valve
needle valve
none of these
butterfly valve
Each term in Bernaulli’s equation represents the __________ of the fluid.
energy per unit mass
energy per unit weight
force per unit mass
none of these
energy per unit weight
Which of the following is a dimensionless parameter ?
Angular velocity
Specific weight
Kinematic viscosity
None of these
None of these
If the head over the triangular notch is doubled, the discharge will increase by __________ times.
2
2.828
5.657
4
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
increase.
decrease.
remain unchanged.
increase or decrease depending on the pipe material.
increase.
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
R
R^2
R^4
R^0.5
R^4
Interstage coolers are provided in a multistage compressor to
save power in compressing a given volume to a given pressure.
cool the delivered air.
achieve the exact delivery pressure.
none of these.
save power in compressing a given volume to a given pressure.
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.
NPSH required.
BHP required by the pump.
head of the liquid pumped.
all of these
all of these
Reynolds number is the ratio of
viscous forces to gravity forces.
inertial forces to viscous forces.
viscous forces to inertial forces.
inertial forces to gravity forces.
inertial forces to viscous forces.
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
For the manometer set up shown in the figure, https://www.indiabix.com/_files/images/chemical-engineering/fluid-mechanics/60-786-1.png, the pressure difference PA - PB is given by
(ρH - ρair)gH
(ρH - ρL)gH
(ρH -ρL) gH + (ρL - ρair) . g(L - H)
(ρH - ρL) gL + (ρL - ρair) gH
(ρH - ρair)gH
The discharge through a venturimeter depends upon
pressure drop only.
its orientation.
co-efficient of contraction only.
none of these.
pressure drop only.
N. second/m^2 is
the S.I. unit of dynamic viscosity.
the S.I. unit of kinematic viscosity.
equivalent to one poise.
equivalent to one stoke.
the S.I. unit of dynamic viscosity.
The distance between metacentre and __________ is called metacentric height.
water surface
centre of gravity
centre of buoyancy
none of these
centre of gravity
Check valve is used for __________ flow.
very precise control of
unidirectional
multidirectional
none of these
unidirectional
Capacity of a rotary gear pump can be varied by
changing the speed of rotation.
bleeding air into suction.
bypassing liquid from the suction or discharge line.
all (a), (6) and (c).
all (a), (6) and (c).
For a given Reynolds number, in a hydraulically smooth pipe, further smoothening __________ the friction factor.
brings about no further reduction of
increases
decreases
none of these
brings about no further reduction of
Power number is the ratio of
drag stress to inertial stress.
inertial stress to drag stress.
inertial stress to gravitational stress.
gravitational stress to drag stress.
drag stress to inertial stress.
The momentum correction factor for the velocity distribution of laminar flow is
1.3
1.66
2.5
none of these
none of these
For the same flow rate of a fluid, the pressure drop is the least for
venturimeter
orificemeter
flow-nozzle
delta-p is same for all
venturimeter
The valve commonly used in pipes larger than 2” dia is a
globe valve
plug-cock
gate valve
check valve
gate valve
Foot valves are provided in the suction line of a centrifugal pump to
avoid priming, every time we start the pump.
remove the contaminant present in the liquid.
minimise the fluctuation in discharge.
control the liquid discharge.
avoid priming, every time we start the pump.
An ideal fluid is
frictionless & incompressible.
one, which obeys Newton’s law of viscosity.
highly viscous.
none of these.
frictionless & incompressible.
In area meter (e.g., rotameter), with increase in the fluid flow rate, the
pressure drop increases linearly.
pressure drop is almost constant.
area through which fluid flows does not vary.
none of these.
pressure drop is almost constant.
In power law, ζ = A (du/dy)² + B, then the fluid is
Newtonian
dilatant
thixotropic
rheopectic
Newtonian
The buoyant force acting on a floating body is dependent on the
viscosity of the liquid.
weight of the liquid displaced.
depth of immersion of the body.
surface tension of the liquid.
weight of the liquid displaced.
A Newtonion fluid is that
which follows Newton’s law of motion.
which needs a minimum shear, before it starts deforming.
for which shear & deformation are related as τ = μ (∂u/∂γ)
none of these.
for which shear & deformation are related as τ = μ (∂u/∂γ)
In case of end to end connection of two or more pipes in series, the __________ each pipe.
same rate of flow passes through
head loss is same through
rate of flow in each pipe is proportional to the length of
total flow rate is the sum of flow rate in
same rate of flow passes through
Which of the following equations applies to the fluid flow through a packed bed for very large Reynolds number ?
Fanning equation
Blake-Pllummer equation
Hagen-Poiseulle equation
Kozney-Karman equation
Blake-Pllummer equation
The flow of gas along a pipe in the direction of decreasing pressure causes decrease in its
viscosity
specific volume
velocity
none of these
specific volume
Centrifugal pump can’t be used to pump
molten sodium (used as a coolant in Fast Breeder Reactor).
moderately viscous vegetable oil used in soap industry.
thick molten soap at 80 C.
none of the above.
thick molten soap at 80 C.
A stream line is
fixed in space in steady flow.
always the path of particle.
drawn normal to the velocity vector at every point.
a line connecting the mid points of flow cross-section.
fixed in space in steady flow.
Quicksand is an example of a __________ fluid.
bingham plastic
dilatent
Newtonion
pseudoplastic
dilatent
Correction for capillary effect in manometers (used for pressure measurement) need not be applied, if diameter of the manometer tube is __________ mm.
< 4
> 4
> 12.5
< 10
> 12.5
Differential manometer measures the
absolute pressure
gauge pressure
pressure difference
pressure gradient
pressure difference
The pressure and power requirement of a gas fan at constant speed & capacity varies __________ the gas density.
directly as
inversely as square root of
inversely as
as square of
directly as
Boundary layer thickness in laminar flow over a flat plate increases as(where, d = distance from the leading edge.)
√d
d^1/3
d^2
d^2/3
√d
Gradually varied flow in open channel is a/an __________ flow.
steady uniform
steady non-uniform
unsteady uniform
unsteady non-uniform
steady non-uniform
The line of action of the buoyant force acts through the
centroid of the displaced volume of fluid.
centre of gravity of a submerged body.
centroid of the volume of any floating body.
none of these.
centroid of the displaced volume of fluid.
Cavitation in a centrifugal pump can be avoided by keeping the
inlet pressure high
outlet pressure low
inlet pressure low
outlet pressure high
inlet pressure high
Vane anemometer
is an area meter.
is a variable head meter.
rotates an element at a speed determined by the velocity of the fluid in which the meter is immersed.
none of these.
rotates an element at a speed determined by the velocity of the fluid in which the meter is immersed.
The peripherial velocity at inlet of a centrifugal pump having inlet diameter of 25 cms and rotating at 950 rpm is __________ m/sec.
1.8
12.4
186.2
736.4
12.4
Laminar flow is characterised by the nonexistence of
pressure fluctuation.
eddies.
deviating velocities.
all (a), (b)&(c).
all (a), (b)&(c).
The length of the tube necessary for the boundary layer to reach the centre of the tube and for fully developed flow to be established is called the __________ length.
equivalent
transition
Prandtl mixing
none of these
transition
Select the correct practical example of steady non-uniform flow.
Motion of water around a ship in a lake.
Motion of river around bridge piers.
Steadily decreasing flow through a reducing section.
Steadily increasing flow through a pipe.
Steadily decreasing flow through a reducing section.
Hydraulic diameter for non-circular ducts is equal to __________ times the area of flow divided by the perimeter.
two
three
four
eight
four
Terminal velocity is
a constant velocity with no acceleration.
a fluctuating velocity.
attained after moving one-half of total distance.
none of these.
a constant velocity with no acceleration.
Consider two pipes of same length and diameter through which water is passed at the same velocity. The friction factor for rough pipe is f1 and that for smooth pipe is f2. Pick out the correct statement.
f1 = f2
f1 < f2
f1 > f2
data not sufficient to relate f1 & f2
f1 > f2
For an incompressible fluid, the bulk modulus of elasticity is
5 kg/m³
∞ N/m²
1 N
0 N/m
∞ N/m²
A fluid is a substance, that
has to be kept in a closed container.
is almost incompressible.
has zero shear stress.
flows when even a small shear is applied to it.
flows when even a small shear is applied to it.
The pressure intensity is the same in all directions at a point in a fluid
only when the fluid is frictionless.
only when the fluid is at rest having zero velocity.
when there is no motion of one fluid layer relative to an adjacent layer.
regardless of the motion of one fluid layer relative to an adjacent layer.
when there is no motion of one fluid layer relative to an adjacent layer.
Which of the following must be followed by the flow of a fluid (real or ideal)? (I) Newton’s law of viscosity. (II) Newton’s second law of motion. (III) The continuity equation. (IV) Velocity of boundary layer must be zero relative to boundary. (V) Fluid cannot penetrate a boundary.
I, II, III
II, III, V
I, II, V
II, IV, V
II, III, V
Mach number is defined as the ratio of the local flow velocity to the sonic velocity in the fluid. For what value of Mach number, the gases are considered incompressible ?
< 0.3
> 3
50
1
< 0.3
Boundary layer exists in flow
of real fluids.
over flat surfaces only.
in pipes only.
of ideal fluids only.
of real fluids.
Rubber latex is an example of __________ fluid.
dilatent
Newtonion
pseudoplastic
Bingham plastic
pseudoplastic
The frictional resistance in laminar flow does not depend on the
area of surface in contact.
flow velocity.
fluid temperature.
pressure of flow.
area of surface in contact.
A venturimeter measures the
velocity head
pressure
point velocity
none of these
none of these
Gradually varying fluid flow is an example of __________ flow.
non-steady uniform
non-steady non-uniform
steady uniform
steady non-uniform
non-steady uniform
Drag is the force component exerted on an immersed object,
passing the centroid of the body at 60 to the direction of motion.
the component being parallel to theflow direction.
the component being normal to the flow direction.
none of these.
the component being parallel to theflow direction.
To handle smaller quantity of fluid at higher discharge pressure, use a __________ pump.
reciprocating
centrifugal
volute
rotary vacuum
reciprocating
Cocks are used to control
water
any liquid
solids
none of these
any liquid
The dimension of surface tension is
ML^-2
MT^-2
MLT^-2
ML^-2T
MT^-2
Pick out the correct statement.
Fanning friction factor is inversely proportional to Reynolds number always.
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.
Mach number in an incompressible fluid is always unity.
Mach number is given by the ratio of the speed of the fluid to that of sound in the fluid under conditions of flow.
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
always inversely proportional to the Reynolds number.
not dimensionless.
not dependent on the roughness of the pipe.
none of these.
none of these.
Rubber latex is an example of a __________ .fluid.
pseudoplastic
bingham plastic
dilatent
Newtonion
pseudoplastic
Which of the following factors does not contribute to the pressure drop in a pipeline ?
Velocity of fluid
Size of pipe
Length of pipe and number of bends
None of these
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
evaporation
cavitation
sublimation
stripping
cavitation
Working of a __________ pump characterises mixed flow.
turbine
piston
diaphragm
none of these
turbine
The rate of change of moment of momentum represents the __________ by the fluid.
torque applied
force exerted
work done
power developed
torque applied
Cd for the orifice plate varies from
0.58 to 0.8
0.93 to 0.98
0.2 to 0.3
0.02 to 0.03
0.58 to 0.8
The discharge through a V-notch weir varies as
H^3/2
H^1/2
H^5/2
H^2/3
H^5/2
Water flow rate in a pipe of 3.5 metres diameter can be most economically and conveniently measured by a/an
pitot tube
venturimeter
orificemeter
rotameter
pitot tube
The specific speed of a pump is defined as the speed of a unit of such a size, that it
delivers unit discharge at unit head.
requires unit power for unit head.
delivers unit discharge at unit power.
none of these.
delivers unit discharge at unit head.
In case of venturimeters, friction losses are about __________ percent of maximum velocity head.
2
8
12
20
2
With increase in the schedule number of a pipe of a particular nominal size, the
wall thickness also increases.
I.D. of the pipe decreases.
O.D. of the pipe remains constant.
all of these
all of these
Turbine impeller
produces only radial current.
produces only tangential current.
is effective over wide range of viscosities.
does not produce tangential current.
is effective over wide range of viscosities.
Friction produced by the formation of wakes is called the __________ friction.
disk
skin
form
none of these
form
wakes form friction
Various efficiencies of a centrifugal pump are related as (where, nm = mechanical efficiency nv = volumetric efficiency. nma = manometric efficiency no = overall efficiency)
nma x nm x nv = no
nm = nv . nma
nma = nm x nv
nv = nm x nma
nm = nv . nma
When the pipe Reynold’s number is 6000, the flow is generally
viscous
laminar
turbulent
transition
turbulent
With a constant diameter impeller of a centrifugal pump
its capacity varies directly as the square of speed.
head varies as the square of speed.
horsepower input varies as the square of speed.
head varies as the speed.
head varies as the square of speed.
For water, when the pressure increases, the viscosity
also increases
decreases
remains constant
first decreases, and then increases
first decreases, and then increases
Location of vena-contracta in an orificemeter does not depend upon the
type of orifice.
density, viscosity & compressibility of the fluid.
ratio of pipe diameter to orifice diameter.
pipe roughness.
type of orifice.
At low Reynolds number
viscous forces are unimportant.
viscous forces control.
viscous forces control and inertial forces are unimportant.
gravity forces control.
viscous forces control and inertial forces are unimportant.
For laminar flow through a closed conduit
Vmax = 2Vav
Vmax = Vav
Vmax = 1.5Vav
Vmax = 0.5Vav
Vmax = 2Vav
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.
inverse
square root
second power
first power
square root
Unsteady uniform flow is represented by flow through a/an
long pipe at constant rate.
long pipe at decreasing rate.
expanding tube at increasing rate.
expanding tube at constant rate.
long pipe at decreasing rate.
If Blausius or Darcey friction factor is ‘f1’ then the Fanning friction factor is equal to
f1/4
4f2
2f1
f1/2
f1/4
Pick out the wrong statement pertaining to fluid flow.
The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
The Newtonion fluid velocity in a circular pipe flow is maximum at the centre of the pipe.
Navier-Stokes equation is applicable to the analysis of viscous flows.
Hagen-Poiseuille equation is applicable to the laminar flow of Newtonion fluids.
The ratio of average velocity to the maximum velocity for turbulent flow of Newtonion fluid in circular pipes is 0.5.
A Newtonion liquid (rho = density, u = viscosity) is flowing with velocity v in a tube of diameter ‘D’. Let delta-p be the pressure drop across the length ‘L’. For a laminar flow, delta-p is proportional to
L rho-v2/D
L u;V/D2
D rho-v^2/L
u V/L
L rho-v2/D
While starting a centrifugal pump, its delivery valve should be kept
opened.
closed.
either opened or closed ; it does not make any difference.
either opened or closed; depending on the fluid viscosity.
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
x
1/sqrt-x
x
1/x
x
Sewage sludge is an example of the __________ fluid.
Bingham plastic
Newtonion
pseudoplastic
dilatent
Bingham plastic
Multistage centrifugal pumps are generally used for
high head.
low head but high discharge.
highly viscous liquid.
slurries of high solid concentration.
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
1.3
0.766
0.87
none of these
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
25.61 kPa
11.77 kPa
14.86 kPa
21.13 kPa
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 ?
Decrease in effect
Increase in thrust
Develops noise
Develops high pressure
Develops high pressure
For a specific centrifugal air blower operating at constant speed & capacity, the power requirement and pressure vary
directly as square of gas density.
directly as gas density.
directly as square root of gas density.
inversely as gas density.
directly as gas density.
Capillary tube method of viscosity measurement is based on the
Hagen-Poiseulle’s equation
Stoke’s law
Navier-stokes equation
none of these
Hagen-Poiseulle’s equation
It is possible to integrate an automatic flow controller to a
flow nozzle
venturimeter
rotameter
none of these
rotameter
For liquid flow through a packed bed, the superficial velocity as compared to average velocity through the channel in the bed is
more
less
equal
independent of porosity
less
For a reciprocating pump, the indicator diagram is the graph between the
discharge and overall efficiency.
volume swept by piston for one complete revolution and the pressure in the cylinder.
angle swept by the crank pin at any instant and the discharge.
none of these.
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.
centrifugal
mixed flow
axial flow
none of these
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^3and viscosity of 3 x 10^-5kg/m.s flowing at 3 m/s will be
8400 Pa/m
12600 Pa/m
18900 Pa/m
16800 Pa/m
12600 Pa/m
One poise (unit of absolute/dynamic viscosity) is equivalent to one
gm/cm^2. sec.
gm/cm. sec.
cm^2/sec.
m2/sec.
gm/cm. sec.
The equation relating friction factor to Reynold number, f^-0.5 = 4 loge (NRe/f)^-0.4, is called the __________ equation.
Nikuradse
Von-Karman
Blausius
Colebrook
Nikuradse
What is the co-efficient of contraction, if a fluid jet discharging from a 50 mm diameter orifice has a 40 mm diameter at its vena-contracta ?
0.64
1.65
0.32
0.94
0.64
Cc = A(vena-contracta)/A(orifice)
Cc = (πDvc²/4) / (πDo²/4)
Cc = Dvc²/Do²
Cc = 40²/50²
Cc = 0.64
For an unstable equilibrium of a floating body (where, M = metacentre.)
M is above G
M is below G
M & G coincide
none of these
M is below G
Which of the following can be used for the direct measurement of volumetric flow rate of slurry ?
Venturimeter
Orificemeter
Rotameter
Pitot tube
Rotameter
A pipe is defined as ‘hydraulically smooth’, if the friction factor
is not a function of Reynolds number.
for a given Reynolds number remains constant even on further smoothening of the pipe.
is zero irrespective of the Reynolds number.
none of these.
for a given Reynolds number remains constant even on further smoothening of the pipe.
A Pitot tube indicates 5 cm of water (manometer) when it is being used for measuring velocity of air. The velocity of air in m/sec is
5
14.1
56.22
28.2
28.2
Delivery of insufficient quantity of liquid by a pump may be caused by
air leak in the inlet
low rpm
too high a lift
all of these
all of these
In case of a __________ the energy of flow is considerably decreased downstream of the machine.
blower
turbine
centrifugal pump
centrifugal fan
turbine
With increase in the shear rate, the apparent viscosity of pseudoplastic fluids
increases
decreases
remains same
may increase or decrease; depends on the magnitude of shear rate
decreases
Co-efficient of discharge (Cd) is defined as actual discharge/theoretical discharge and is equal to Cc . Cv; where Cc = Co-efficient of contraction and Cv = co-efficient of velocity. Cd of an orifice is usually about
0.42
0.62
0.82
0.98
0.62
Purpose of hydraulic accumulator is to
ensure intermittant supply of hydraulic pressure.
increase the pressure and store/ accumulate it.
accumulate pressure to increase force.
generate high pressure to operate hydraulic machines like cranes, lifts, presses etc
generate high pressure to operate hydraulic machines like cranes, lifts, presses etc
HH high pressure - hydraulic accumulator
Pick out the wrong statement.
Surface tension of a liquid is because of the difference in magnitude of adhesive & cohesive forces.
A hydrometer used for the determination of specific gravities of liquids works on the principle of buoyant forces.
In case of unsteady fluid flow, the velocity at any given point does not change with time.
Turbulent fluid flow is characterised by the rapid fluctuation of instantaneous pressure & velocity at a point.
In case of unsteady fluid flow, the velocity at any given point does not change with time.
Purpose of relief valve in a reciprocating pump is to
protect the pump against developing excessive pressure.
facilitate unidirectional flow of liquid.
reduce the discharge pressure.
control the rate of discharge.
protect the pump against developing excessive pressure.
Select the correct statement.
The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter.
A venturimeter with a given gage difference discharges at a greater rate, when the flow is vertically downward through it, than when the flow is vertically upward.
For a given pressure difference, the discharge of gas is greater through a venturimeter, when compressibility is taken into account, than when it is neglected.
The overall pressure loss is the same in a given pipe line, whether a venturimeter or a nozzle with the same throat dia is used.
The discharge through a venturimeter depends upon Δp only and is independent of orientation of the meter.
Remember: correct statement upon Δp only
In case of turbulent flow of fluid through a circular pipe, the
mean flow velocity is about 0.5 times the maximum velocity.
velocity profile becomes flatter and flatter with increasing Reynolds number.
point of maximum instability exists at a distance of 2r/3 from the pipe wall (r = pipe radius).
skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.
skin friction drag, shear stresses, random orientation of fluid particles and slope of velocity profile at the wall are more.
What is the maximum theoretical suction lift (metres) of a reciprocating pump ?
5
10
50
100
10
The terminal velocity of a particle moving through a fluid varies as dp^n. The value of n is equal to __________ in Stoke’s law regime.
1
0.5
2
1.5
2
Function of air vessel provided in a reciprocating pump is to
reduce discharge fluctuation.
reduce the danger of cavitation.
avoid the necessity of priming.
increase the pump efficiency.
reduce discharge fluctuation.
The Prandtl pitot tube measures the
velocity at a point in the flow.
pressure at a point.
average flow velocity.
pressure difference in pipe flow.
velocity at a point in the flow.
Pressure drop in packed bed for turbulent flow is given by the __________ equation.
Kozney-Karman
Blake-Plummer
Leva’s
Hagen-Poiseulle’s
Blake-Plummer
In the complete turbulence zone (in rough pipes), the
rough and smooth pipes have the same friction factor.
laminar film covers the roughness projections.
friction factor depends upon NRe only.
friction factor is independent of the relative roughness.
friction factor is independent of the relative roughness.
Which of the following has the minimum compressibility ?
Water at room temperature
Air at room temperature
Oxygen at room temperature
Nitrogen at room temperature
Water at room temperature
In case of centrifugal fan or blower, the gas capacity varies as
speed
(speed)^2
(speed)^3
(speed)^0.5
speed
Pick out the wrong statement.
A fluid mass is free from shearing forces, when it is made to rotate with a uniform velocity.
Newton’s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution.
Laminar flow of viscous liquids is involved in the lubrication of various types of bearings.
Rise of water in capillary tubes reduces with the increasing diameter of capillary tubes.
Newton’s law of viscosity is not applicable to the turbulent flow of fluid with linear velocity distribution.
Pick out the wrong statement.
In a static mass of liquid, the pressure at a point is the same for all liquids.
Pressure decreases exponentially with elevation in an isothermal atmosphere.
Atmospheric pressure = absolute pressure-gage pressure.
As per Pascal’s law, the pressure at a point in a static or uniformly moving fluid is equal in all directions.
In a static mass of liquid, the pressure at a point is the same for all liquids.
The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is
parabolic
flat
flat near the wall and parabolic in the middle
parabolic near the wall and flat in the middle.
parabolic near the wall and flat in the middle.
Mach number is the ratio of the speed of the
fluid to that of the light.
light to that of the fluid.
fluid to that of the sound.
sound to that of the fluid.
fluid to that of the sound.
A piezometer opening measures the __________ fluid pressure.
static
undisturbed
total
dynamic
undisturbed
Drag force on the float of a rotameter is(where Q = flow rate of the )
is propotional to Q
is propotional to sqrt-Q
is propotional to Q2
constant
constant
The unit of dynamic viscosity in SI unit is
kg/m . sec
N/m^2
m^2 /sec.
m/N. sec.
kg/m . sec
Pressure drop (delta-p) for a fluid flowing in turbulent flow through a pipe is a function of velocity (V) as
V^1.8
V^-0.2
V^2.7
V^2
V^2
Dean number is concerned with the
fluid-particle interaction.
fluid flow through helical pipes.
power consumption in agitated vessels.
psychrometry.
fluid flow through helical pipes.
The equation given below is called the __________ .
F^-0.5 = 4.07 loge (NResqrt-f)^-0.6
Colebrook formula
Von-Karman equation
Fanning equation
none of these
Von-Karman equation
Poise is converted into stoke by
multiplying with density (gm/c.c).
dividing by density (gm/c.c).
multiplying with specific gravity.
dividing by specific gravity.
dividing by density (gm/c.c).
The fluid velocity varies as the square root of the cylindrical pipe diameter in case of steady state laminar flow at constant pressure drop fo __________ fluid.
dilatant
pseudoplastic
Bingham plastic
Newtonion
dilatant
square root cylindrical laminar dilatant
Kinetic energy of fluid per unit weight represented by the velocity head is given by
2v^2/gc
v^2/2gc
rho-v^2/gc
rho-.v^2/2gc
v^2/2gc
At a constant speed of the centrifugal pump . it __________ the impeller diameter.
capacity varies directly with
head varies as the square of
horsepower varies as the cube of
all of these
all of these
The pressure co-efficient is the ratio of pressure forces to __________ forces.
viscous
inertial
gravity
surface tension
viscous
