JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II FLUID MECHANICS AND HEAT TRANSFER Previous Question Paper (April/May - 2023 - R16)

B.Tech | II | II | R16 | April/May - 2023

Answer PaperPaper Code: 134BBMaximum Marks: 75Time: 3 Hours

Note: i) Question paper consists of Part A, Part B. ii) Part A is compulsory, which carries 25 marks. In Part A, Answer all questions. iii) In Part B, Answer any one question from each unit. Each question carries 10 marks and may have a, b as sub questions.

PART - A

125 marks
a
State the condition for Irrotational flow.
2 marks

Answer

A flow is considered irrotational if the vorticity vector is zero at every point in the flow field. Mathematically, this is expressed as the curl of the velocity vector being zero: ∇ × V = 0. In Cartesian coordinates, this implies that the angular velocity components about the x, y, and z axes are all zero.

b
Classify different types of flows with example.
3 marks

Answer

Flows are classified based on time and space variations:

  • Steady and Unsteady flow: Steady flow properties do not change with time (e.g., flow through a pipe at constant discharge). Unsteady flow properties change with time (e.g., flow during pipe start-up).
  • Uniform and Non-uniform flow: Uniform flow velocity does not change with location (e.g., flow through a constant diameter pipe). Non-uniform flow velocity changes with location (e.g., flow through a tapering pipe).
  • Laminar and Turbulent flow: Laminar flow involves fluid particles moving in smooth layers (e.g., oil flow in a capillary). Turbulent flow involves chaotic, eddy-driven motion (e.g., high-velocity flow in a river).
c
Derive momentum equation.
2 marks

Answer

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d
Write the expressions for cv, cc and cd for an orifice.
3 marks

Answer

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e
Define conduction.
2 marks

Answer

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f
Explain different modes of heat transfer.
3 marks

Answer

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g
Define Euler number and Weber number.
2 marks

Answer

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h
Explain about maximum and minimum heat dissipation.
3 marks

Answer

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i
Define gray body.
2 marks

Answer

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j
With a neat sketch, explain parallel flow heat exchanger.
3 marks

Answer

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PART - B

210 marks
a
Define and distinguish between streamline, path line and streak line.
5 marks

Answer

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b
The flow field is given by ψ = x3y. Check whether the given field exists or not? Further check whether it is irrotational?
5 marks

Answer

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OR
310 marks
a
Define and distinguish between (i) steady and unsteady flow (ii) uniform and non-uniform flow (iii) rotational and irrotational flow.
5 marks

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b
Determine whether the following velocity components satisfy the continuity equation. i) u = cx, v = -cy ii) u = -cx/y, v = c log xy.
5 marks

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410 marks
a
Write Euler’s equation of motion. State the Bernoulli’s equation and write the assumption made in it. How is it modified while applying in practice.
5 marks

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b
A pipe through which water is flowing, is having diameters, 20cm and 10cm at the cross-sections 1 and 2 respectively. The velocity of water at section 1 is given as 4 m/s. Find the velocity head at sections 1 and 2 and also rate of discharge.
5 marks

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OR
510 marks
a
What are the surface and body forces associated with fluid flow? How are they incorporated in Euler’s equation?
5 marks

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b
A 30-cm diameter horizontal pipe terminates in a nozzle with the exit diameter of 7.5 cm. If the water flows through the pipe at the rate of 0.15 m3/s. What force will be exerted by the fluid on the nozzle?
5 marks

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610 marks
a
Derive the general heat conduction equation in Cartesian coordinates.
5 marks

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b
A large slab of aluminium at a uniform temperature of 200°C suddenly has its surface temperature lowered to 70°C. What is time when the temperature at a depth 4 cm has dropped to 120°C.
5 marks

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OR
710 marks
a
What is critical radius? Why it is necessary? Derive expression of critical radius for Spherical shape.
5 marks

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b
A wall of 0.5 m thickness is to be constructed of a material which has an average thermal conductivity of 1.4 W/mK. The wall is to be insulated with a material having a thermal conductivity of 0.35 W/mK. Heat loss/m2 is not to exceed 450W. Assuming that the inner and outer surface temperatures are 1200°C and 15°C calculate the thickness of insulation required.
5 marks

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810 marks
a
Explain the development of velocity and thermal boundary layers for flow over a flat plate.
5 marks

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b
Calculate the convective heat transfer from a radiator 0.5m wide and 1m high at 84°C in a room at 20°C. Treat the radiator as a vertical plate.
5 marks

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OR
910 marks
a
Air at 20°C at 3m/s flows over a thin plate of 2m long and 1m wide at 100°C. Estimate the boundary layer thickness at the trailing edge, total drag force, mass flow of air between x = 30cm and x = 80 cm. Also, calculate heat transferred. Take viscosity = 15 × 10-6 kg/ms and density = 1.17 kg/m3.
8 marks

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b
Write about Colburn’s analogy.
2 marks

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1010 marks
a
What is fouling in heat exchangers? How is it specified?
5 marks

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b
Explain Plate type heat exchanger with its advantage and disadvantage.
5 marks

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OR
1110 marks
a
A furnace is approximated as an equilateral triangular duct of sufficient length so that end effects can be neglected. The hot wall of the furnace is maintained at 900 K and has an emissivity of 0.8. The cold wall is at 400 K and has the same emissivity. Find the net radiation heat flux leaving the wall. Third wall of the furnace may be assumed as a reradiating surface.
5 marks

Answer

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b
An enclosure measures 1.5m × 1.5m with a height of 2m under steady state conditions. The wall and ceiling are maintained at 525 K and floor is at 400K. Determine net radiation to floor. Take emissivity of ceiling and wall = 0.85 and emissivity of floor = 0.75.
5 marks

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About this paper

This page contains the solved question paper with answers of FLUID MECHANICS AND HEAT TRANSFER from JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD for B.Tech MECT-MCT-MEM II II, April/May - 2023, R16.

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