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Fluid Mechanics > section 3 > Flashcards

section 3 Flashcards

1
Q

Pick out the wrong statement.
a. The form drag is dependent upon the occurrence of a wake.
b. The shear stress at any given cross-section of a pipe for steady flow (either laminar or turbulent) varies linearly as the radial distance.
c. An ideal fluid is the one, which has negligible surface tension and obeys the Newton’s law of viscosity.
d. Existence of the boundary layer in fluid flow is because of viscosity of the fluid.

A

c

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2
Q

Mass velocity is independent of temperature & pressure, when the flow is
a. unsteady through unchanged cross-section.
b. steady through changing cross-section.
c. steady and the cross-section is unchanged.
d. unsteady and the cross-section is changed.

A

c

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3
Q

Very small pressure difference (< 5 mm water coloumn) can be most conveniently measured by a/an __________ manometer.
a. U-tube water.
b. U-tube mercury.
c. inclined tube mercury.
d. inclined tube water.

A

d

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4
Q

For pipe flows, head is proportional to __________ at constant capacity(where, D = pipe diameter).
a. 1/D
b. 1/D2
c. 1/D5
d. D2

A

c

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5
Q

For a given Reynold number as d/D for an orifice increases, Cd will (where, d & D are orifice & pipe diameters respectively).
a. increase
b. decrease
c. remain constant
d. either (a) or (b); depends on other factors

A

a

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6
Q

word file

A
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7
Q

word file

A
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8
Q

A differential pressure cell is used for
a. measuring small pressure difference in gases.
b. measuring small pressure difference in liquids.
c. remote recording of pressure difference.
d. measuring the difference of the impact & the static pressure.

A

c

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9
Q

If more than two branches of pipes are to be connected at the same point, then use a/an
a. elbow
b. union
c. tee
d. none of these.

A

c

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10
Q

In case of a centrifugal pump, the ratio of total delivered pressure to pressure developed with the impeller is called the __________ efficiency.
a. manometric
b. mechanical
c. volumetric
d. overall

A

a

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11
Q

Acceleration head in a reciprocating pump
a. increases the work done during delivery stroke.
b. decreases the work done during suction stroke.
c. does not change the work requirement of the pump.
d. increases the work done during suction stroke.

A

c

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12
Q

The ratio of inertial forces to elastic forces is called the __________ number.
a. Reynolds
b. Mach
c. Euler
d. Weber

A

b

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13
Q

word

A
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14
Q

Fluid flow at increasing rate through a diverging pipe is an example of __________ flow.
a. steady uniform
b. non-steady uniform
c. steady non-uniform
d. non-steady non-uniform

A

d

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15
Q

word

A
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15
Q

The temperature in isentropic flow
a. does not depend on Mach number.
b. depends on Mach number only.
c. cannot drop and then increase again downstream.
d. none of these.

A

b

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16
Q

Check in a centrifugal pump is
provided in the discharge line.
generally a globe valve.
provided to prevent liquid from backing up through the pump when the pump is turned off or accidently stops running.
all (a), (b) and (c).

A

d

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17
Q

Centrifugal pump is normally classified on the basis of the
a. rpm.
b. type of casing.
c. impeller blade angle.
d. number of blades in impeller.

A

b

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18
Q

Drag force acting on a body does not depend upon the
a. density of the fluid.
b. density of the body.
c. velocity of the body.
d. projected area of the body.

A

b

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19
Q

Where does the maximum stress occur in case of laminar flow of incompressible fluid in a closed conduit of diameter ‘d’?
a. At the centre
b. At d/4 from the wall
c. At the wall
d. At d/8 from the wall

A

c

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20
Q

word

A
21
Q

Applying a pressure drop across a capillary results in a volumetric flow rate ‘Q’ under laminar flow conditions. The flow rate for the same pressure drop, in a capillary of the same length but half the radius is
a. Q/2
b. Q/4
c. Q/8
d. Q/16

A

d

22
Q

WORD

A
23
Q

In an incompressible fluid, the density is
a. greatly affected by moderate changes in pressure.
b. greatly affected only by moderate changes in temperature.
c. not affected with moderate change in temperature & pressure.
d. sensible to changes in both temperature & pressure.

A

c

24
Q

Check valves are used
a. at high pressure.
b. in bends.
c. for controlling water flow.
d. for unidirectional flow.

A

d

25
Q

Velocity distribution for flow between two fixed parallel plates
a. varies parabolically across the section.
b. is constant over the entire cross-section.
c. is zero at the plates and increases linearly to the midplane.
d. none of these.

A

a

26
Q

Priming is needed in a __________ pump.
a. reciprocating
b. gear
c. centrifugal
d. diaphragm

A

c

26
Q

An ideal nozzle design aims at
a. minimising wall friction.
b. suppressing boundary layer separation.
c. both (a) & (b).
d. neither (a) nor (b).

A

c

27
Q

Which of the fluid forces are not considered in the Reynold’s equation of flow ?
a. Viscous forces
b. Turbulent forces
c. Pressure forces
d. Compressibility forces

A

d

28
Q

For ideally incompressible fluid, the Mach number will be
a. 1.5
b. 1
c. 0
d. 5

A

b

29
Q

A mono pump is a __________ pump.
a. centrifugal
b. piston
c. positive acting rotary
d. a group of vacuum

A

c

30
Q

Higher specific speed (200-500) of a centrifugal pump indicates that the pump is of __________ flow type.
a. axial
b. radial
c. mixed
d. none of these

A

a

31
Q

The variable required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are
P. Inlet pressure Q. Compressor rpm
R. Delivery pressure S. Volumetric flow rate at inlet.
a. P, Q and R
b. P and R
c. R and S
d. P, Rand S

A

a

32
Q

Theoretical head developed by a centrifugal pump does not depend upon the __________ the impeller.
a. radius of
b. speed of
c. fluid velocity leaving
d. none of these

A

d

33
Q

An ideal fluid is
a. non-viscous
b. incompressible
c. both (a) & (b)
d. neither (a) & (b)

A

c

34
Q

word

A
35
Q

In case of isentropic flow, the speed of sound in an ideal gas is proportional to (where M = molecular weight of the gas)
a. 1/sqrt M
b. sqrtM
c. 1/M
d. M

A

a

36
Q

Boundary layer separation is caused by the
a. reduction of pressure to vapour pressure.
b. boundary layer thickness reducing to zero.
c. adverse pressure gradient.
d. reduction of pressure gradient to zero.

A

c

37
Q

With increase in temperature, the vapor pressure of liquids
a. increases
b. increases linearly
c. decreases
d. remains constant

A

a

38
Q

A mercury (specific gravity = 13.6) manometer connected across an orificemeter fitted in a pipe shows a manometer reading of 2 cms. If the manometer liquid is changed to carbon tetrachloride (specific gravity = 1.6), then for the same flow rate of water the new manometer reading will be __________ cms.
a. 17
b. 42
c. 84
d. 1.8

A

a

39
Q

The ratio of wall drag to total drag in the Stoke’s law range is
a. 0.5
b. 1
c. 1/3
d. 2/3

A

d

40
Q

Rotary vacuum pumps can reduce the absolute pressure to as low as __________ mm Hg.
a. 1
b. 0.1
c. 0.01
d. 0.001

A

c

41
Q

The most suitable flow measuring device for the fluid flow measurement in a very large diameter pipeline is a
a. weir
b. pitot tube
c. Kennison nozzle
d. V-notch

A

b

42
Q

A pitched-blade turbine draws __________ a straight blade turbine.
a. less power than
b. more power than
c. same power as
d. data insufficient to predict

A

a

43
Q

A centrifugal pump is called a turbine pump, if it is having a
a. turbine type impeller.
b. vaned diffusion casing.
c. rotating vaned volute.
d. none of these.

A

b

44
Q

Remote control valve is a __________ valve.
a. gate
b. butterfly
c. needle
d. globe

A

b

45
Q

Which of the following quantities are computed by using the hydraulic radius for non-circular ducts ?
a. Velocity and relative roughness.
b. Head loss and velocity.
c. Reynold number, relative roughness and head loss.
d. Reynolds number and friction factor.

A

c

46
Q

Centre of pressure in an immersed body is __________ the centre of gravity.
a. above
b. below
c. at
d. either above or below; depends on the liquid density

A

b

47
Q

The centre of pressure is
a. always below the centroid of the area.
b. always above the centroid of the area.
c. a point on the line of action of the resultant force.
d. at the centroid of the submerged area.

A

c

48
Q

The uniformity of a gas fluidised bed depends upon the __________ of the solid particles.
a. size
b. surface properties
c. both (a) and (b)
d. neither (a) nor (b)

A

c

Fluid Mechanics (4 decks)

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