Fluid Mechanics

Question: For Laminar flow through a packed bed, the pressure drop is proportional to (Vs is the superficial liquid velocity and Dp is the particle diameter)
[A].

Vs/Dp2

[B].

Vs2/Dp2

[C].

Vs2/Dp3

[D].

Vs/Dp3

Answer: Option A

Explanation:

No answer description available for this question.

Question: 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
[A].

d

[B].

d2

[C].

d2.5

[D].

d4

Answer: Option C

Explanation:

No answer description available for this question.

Question: 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
[A].

26

[B].

42

[C].

269

[D].

325

Answer: Option C

Explanation:

No answer description available for this question.

Question: In centrifugal pumps, cavitation occurs, when pressure of the impeller eye or vane becomes
[A].

less than atmospheric pressure.

[B].

more than liquid vapor pressure.

[C].

less than liquid vapor pressure.

[D].

more than atmospheric pressure.

Answer: Option C

Explanation:

No answer description available for this question.

Question: Bed pressure drop in an air fluidised bed of catalyst particles (ρp = 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
[A].

90

[B].

60

[C].

45

[D].

30

Answer: Option B

Explanation:

No answer description available for this question.

Question: A bed consists of particles of density 2000 kg/m3. 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
[A].

25.61 kPa

[B].

11.77 kPa

[C].

14.86 kPa

[D].

21.13 kPa

Answer: Option B

Explanation:

No answer description available for this question.

Question: 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
[A].

5

[B].

14.1

[C].

56.22

[D].

28.2

Answer: Option D

Explanation:

No answer description available for this question.

Question: For laminar flow of a shear thinning liquid in a pipe, if the volumetric flow rate is doubled, the pressure gradient will increase by a factor of
[A].

2

[B].

<2

[C].

>2

[D].

1/2

Answer: Option A

Explanation:

No answer description available for this question.

Question: 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

Answer: Option D

Explanation:

No answer description available for this question.

Question: Boundary layer separation is characterised by one of the conditions given below, where ‘Re’ is the Reynolds number for the flow. Select the appropriate conditions.
[A].

Re << 1, accelerating flow

[B].

Re >> 1, accelerating flow

[C].

Re << 1, decelerating flow

[D].

Re >>1, decelerating flow

Answer: Option D

Explanation:

No answer description available for this question.