Code No: A65C2 R 22
BVRAJU INSTITUTE OF TECHNOLOGY, NARSAPUR
(UGC - AUTONOMOUS)
III B.Tech I Semester Regular Examinations, Dec. – 2024
INTERNAL COMBUSTION ENGINES AND GAS TURBINES
(MECHANICAL ENGINEERING)
Time: 3 Hours Max Marks: 60
Note: This Question Paper contains two Parts A and B
Part A is compulsory which carries 10 marks. Ten questions from five units. Answer all questions in
Part A at one place only.
Part-B consists of 5 Questions (numbered from 2 to 6) carrying 10 marks each. Each of these
questions is from one unit and may contain a, b, c as sub-questions. For each question there will be an
either/or choice (that means there will be two questions from each unit and the student should answer
only one question).
PART – A (10x1 = 10 Marks)
1. Marks Bloom Level CO
a Explain the significance of the fuel-air cycle. 1 2 1
b List three principal factors that influence engine performance? 1 1 1
c What is the importance of valve and port timing diagrams of I C 1 2 2
Engines.
d How the fuel injection system function in CI Engine? 1 2 2
e Define knocking in SI engines. 1 1 3
f List out the three desirable properties of CI engine fuels. 1 1 4
g List various methods available for finding friction power of an 1 1 5
engine.
h What is the need for measurement of speed of an I.C. engine? 1 1 5
i Define work ratio with reference to Gas turbines. 1 1 6
j Explain Inter cooling method in gas turbines. 1 2 6
PART – B (5x10 = 50 Marks)
Marks Bloom Level CO
2 .a Why the actual cycle efficiency is much lower than the air 10 2 1
standard cycle efficiency? Explain the major losses in the actual
engine.
OR
2.b Briefly explain the following: (i) time loss factor (ii) heat loss 10 2 1
factor (iii) exhaust blowdown factor.
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3.a Explain the working principle of four stroke SI engine with the 10 2 2
help of neat sketches.
OR
3.b Explain the working of any one battery ignition system with the 10 2 2
neat sketch.
***
4.a Briefly explain the stages of combustion in SI engines elaborating 10 2 3
the flame front propagation.
OR
4.b What are the types of combustion chambers used in C.I. engines 10 4 4
and explain their role in generating turbulence.
***
5.a Schematically explain the use of the study of heat balance of an 10 5 5
engine?
OR
5.b A 4 cylinder, 4 stroke gasoline engine having a bore of 80 mm 10 3 5
and stroke of 90 mm has a compression ratio of 8. The relative
efficiency is 65% when indicated fuel specific consumption (ifsc)
is 200 gm/kwhr. Estimate: i) Calorific value of fuel ii)
Corresponding fuel consumption, given that indicated mean
effective pressure (imep) is 7.5 bar and speed is 2000 RPM.
***
6.a Clearly explain the various methods to improve thermal efficiency 10 4 6
of an open cycle Gas turbine with the help of neat line diagrams
and T – s diagrams,
OR
6.b A simple gas turbine cycle has a pressure ratio of six and a 10 3 6
maximum cycle temperature of 600oC. The isentropic efficiencies
of compressor and turbine are 82% and 85% respectively.
Calculate the power output in kW of an electric generator geared
to the turbine when the air enters the compressor at 15oC at the
rate of 15 kg/s.
Take: Cp = 1.005 kJ/kgK and γ = 1.4 for compression process.
Cp = 1.11 kJ/kgK and γ = 1.333 for expansion process.
***
