Download GTU BE/B.Tech 2018 Winter 8th Sem Old 181904 Thermal Engineering Question Paper

Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2018 Winter 8th Sem Old 181904 Thermal Engineering Previous Question Paper

1
Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE - SEMESTER ?VIII (OLD) EXAMINATION ? WINTER 2018
Subject Code: 181904 Date: 03/12/2018

Subject Name: Thermal Engineering

Time: 02:30 PM TO 05:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.
Q.1 (a) Define the term ?steam nozzle? and state its application. Explain in brief various
types of nozzles.
07
(b) Explain the working of ramjet engine with a neat sketch and also state its
applications.
07

Q.2 (a) State the various methods of governing of steam turbines. Explain nozzle
governing with neat sketch.
07
(b) Explain in brief the various internal and external losses in steam turbines. 07
OR
(b) In an air standard gas turbine engine, air at a temperature of 15
0
C and a pressure of
1.01 bar enters the compressor, where it is compressed through a pressure ratio of
5. Air enters the turbine at a temperature of 815
0
C and expands to original pressure
of 1.01 bar.
Determine the thermal efficiency and the ratio of turbine work to compressor work
when the engine operates on an ideal Brayton cycle. Take ? = 1.4,
Cp = 1.005 kJ/kg
0
K.
07

Q.3 (a) Derive an expression for mass flow rate of steam through the nozzle in terms of
initial pressure, initial specific volume, area of cross-section, final pressure and
index ?n?.
07
(b) Derive the expression for critical velocity in a nozzle in terms of local sonic
velocity at inlet conditions and isentropic index of expansion.
07
OR
Q.3 (a) Explain pressure compounded impulse steam turbine. State its advantages and
disadvantages.
07
(b) With schematic and T-S diagram explain gas turbine cycle with intercooling,
regeneration and reheating.
07

Q.4 (a) Define the terms with respect to steam turbine:-
(i) Blade efficiency (ii) Blade speed ratio (iii) Work done (iv) Axial thrust (v)
Stage efficiency (vi) Tangential force (vii) Carry over coefficient
07
(b) Write a short note on ?Pulse Jet Engine?. 07
OR
Q.4 (a) With a neat sketch explain closed cycle gas turbine plant. What are the advantages
of closed cycle over open cycle gas turbine plant?
07
(b) Write a short note on ?Turbo prop engine?. 07

Q.5 (a) Give a brief comparison of impulse and reaction steam turbines. 07
(b) Define reheat factor and internal efficiency. Derive the relation between stage
efficiency, internal efficiency and reheat factor.
07
OR

Q.5 (a) State the merits and demerits of gas turbine over steam turbine. 07
(b) Explain any three methods of blade fixation on the turbine rotor with neat sketch. 07

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