Fluid Mechanics Part 1 Flashcards
The fluid property, due to which, mercury does not wet the glass is
surface tension
viscosity
cohesion
adhesion
surface tension
Laminar flow of a Newtonion fluid ceases to exist, when the Reynolds number exceeds
4000
2100
1500
3000
2100
When the momentum of one fluid is used for moving another fluid, such a device is called a/an
jet pump
blower
acid egg
none of these
jet pump
The head loss in turbulent flow in a pipe varies
as velocity
as (velocity)^2
inversely as the square of diameter
inversely as the velocity
as (velocity)^2
Most commonly used joint in the underground pipe lines is the
sleevejoint
coupling
flange
expansion joint
sleevejoint
Schedule number of a pipe, which is a measure of its wall thickness, is given by
1000 P’/S
100 P’/S
1000 S/P’
10000 P’/S
1000 P’/S
The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the
discharge.
suction.
suction minus vapor pressure of the liquid at suction temperature.
discharge minus vapor pressure of the liquid at the discharge temperature.
suction minus vapor pressure of the liquid at suction temperature.
With increasing flow rate, the hydraulic efficiency of a centrifugal pump
monotonically decreases.
decreases and then increases.
remains constant.
increases and then decreases.
monotonically decreases.
The velocity profile for turbulent flow through a closed conduit is
logarithmic
parabolic
hyperbolic
linear
logarithmic
In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness. Two pipes are said to have the same hydraulic roughness, when they have equal values of
relative roughness.
absolute roughness.
friction co-efficient for flows at equal Reynold number.
all of these.
friction co-efficient for flows at equal Reynold number.
Water hammer in a pipeline results from the
bursting of pipelines due to closure by a valve.
rapid pressure change due to a rapid change in the rate of flow.
pressure increase due to closure of a valve resulting in decrease in rate of flow.
none of these.
rapid pressure change due to a rapid change in the rate of flow.
Molten soap mass is transported by a __________ pump.
diaphragm
reciprocating
gear
centrifugal
centrifugal
Which of the following denotes the effect of compressibility in fluid flow ?
Weber number
Mach number
Euler number
Reynolds number
Mach number
Nominal size of the discharge pipe of a pump is usually __________ the nominal size of the inlet pipe.
smaller than
larger than
same as
twice
smaller than
The terminal velocity of a small sphere settling in a viscous fluid varies as the
first power of its dimeter.
inverse of the fluid viscosity.
inverse square of the diameter.
square of the difference in specific weights of solid & fluid.
inverse of the fluid viscosity.
If the discharge of a centrifugal pump is throttled, then its suction lift
increases
decreases
remains unchanged
data insufficient to predict
increases
Foot valves provided in pumps are __________ valves.
relief
three/four way
pressure reducing
directional control
directional control
At high Reynolds number
inertial forces control and viscous forces are unimportant.
viscous forces predominate.
inertial forces are unimportant and viscous forces control.
none of these.
inertial forces control and viscous forces are unimportant.
Power loss in an orificemeter is __________ that in a venturimeter.
less than
same as
more than
data insufficient, cannot be predicted
more than
The terminal velocity of a particle moving through a fluid varies as dpn. What is the value of n’ for Newton’s law regime ?
0.5
1
1.5
3
0.5
What is the normal range of exit cone angle of a venturimeter ?
2 to 5
7 to 15
15 to 25
>25
7 to 15
The dimension of dynamic viscosity is
ML^-1T^-1
L2T^-1
LT^-2
ML^-1T^-2
ML^-1T^-1
A particle A of diameter 10 microns settles in an oil of specific gravity 0.9 and viscosity 10 poise under Stoke’s law. A particle B with diameter 20 microns settling in the same oil will have a settling velocity
same as that of A.
one fourth as that of A.
twice as that of A.
four times as that of A.
one fourth as that of A.
The pitot static tube does not measure the __________ pressure.
static
total
difference in static & dynamic
all of these
all of these