Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 4th Sem 3142507 Fluid Mechanics And Heat Transfer Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?IV (NEW) EXAMINATION ? WINTER 2020
Subject Code:3142507 Date:11/02/2021
Subject Name:Fluid Mechanics and Heat Transfer
Time:02:30 PM TO 04:30 PM Total Marks:56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Marks
Q.1 (a) What do you understand by hydrostatic paradox?
03
(b) State and prove Pascal's law.
04
(c) Derive Euler's equation of motion. State assumptions made. How will
07
you obtain Bernoulli's equation from Euler's equation?
Q.2 (a) Define centre of pressure. Obtain expression for centre of pressure for
03
vertical plane surface submerged in liquid.
(b) With neat sketch explain the stability conditions of submerged body.
04
(c) Enunciate Newton's law of viscosity. Explain importance of viscosity in
07
fluid motion. What is the effect of temperature on viscosity of water and
air?
Q.3 (a) Define the terms: Unsteady flow, Three dimensional flow, Uniform flow
03
(b) How repeating variables selected for dimensionless analysis?
04
(c) The water is flowing through a taper pipe of length 100 m having
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diameters 600 mm at the upper end and 300 mm at the lower end, at the
rate of 50 lps. The pipe has slope of 1 in 30. Find the pressure at the lower
end if pressure at the higher level is 19.62 N/cm2.
Q.4 (a) Explain electrical analogy of the heat transfer with the help of thermal
03
network.
(b) Define the terms: heat capacity and thermal diffusivity with their
04
physical significance.
(c) Derive general heat conduction equation in Cartesian coordinate system.
07
Reduce the equation to Laplace equation.
Q.5 (a) Explain the mechanism of convection heat transfer. Also explain natural
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and forced convection.
(b) What are dimensionless numbers? Explain physical significance of
04
Nusselt Number and Prandtl Number
(c) A furnace wall consists of 200 mm layer of refractory bricks, 6 mm layer
07
of steel plate and a 100 mm layer of insulation bricks. The maximum
temperature of the wall is 1150?C on the furnace side and the minimum
temperature is 40?C on the outermost side of the wall. An accurate
energy balance over the furnace shows that the heat loss from the wall is
400 W/m2. It is known that there is a thin layer of air between the layers
of refractory bricks and steel plate. Thermal conductivities for the three
layers are 1.52, 45 and 0.138 W/m?C respectively. Find :
i. To how many millimetres of insulation brick is the air layer
equivalent?
ii. What is the temperature of the outer surface of the steel plate ?
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Q.6 (a) Explain the concept of thermal boundary layer.
03
(b) Explain the following:
04
i.
Fin efficiency
ii.
Fin effectiveness
(c) By dimensionless analysis show that for forced convection Nu = f (Re,
07
Pr)
Q.7 (a) Define the tems: Absorptivity, Reflectivity, Transmittivity.
03
(b) State and prove Kirchoff's law of radiation.
04
(c) Derive the equation of heat exchange between two infinite parallel planes
07
of non-black body.
Q.8 (a) State limitations of LMTD method.
03
(b) State and explain Wein's displacement law.
04
(c) The flow rates of hot and cold water streams running through a parallel-
07
flow heat exchanger are 0.2 kg/s and 0.5 kg/s respectively. The inlet
temperatures on the hot and cold sides are 75?C and 20?C respectively.
The exit temperature of hot water is 45?C. If the individual heat transfer
coefficients on both sides are 650 W/m2?C, calculate the area of the heat
exchanger.
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This post was last modified on 04 March 2021