STUPIDSID
Answer the following any four:-
1 (a)
Explain the main functions of fuel supply system in C.I. engines.
5 M
1 (b)
Explain the phenomenon of pre-ignition. Explain how pre-ignition leads to detonation and vice versa.
5 M
1 (c)
Explain how induction swirl is created? What are the requirements of injector for this type of swirl?
5 M
1 (d)
Describe the phenomenon of knocking in S.I. engines with the help of P-? and P-V plots.
5 M
1 (e)
Give a brief classification of diesel injection system with explanation of any one system.
5 M
2 (a)
A four cylinder, four stroke, square engine running at 2400rpm has a carburettor venturi with a 30m throat. The engine cylinder bore is 100mm and volumetric efficiency 75%. Take density of air as 1.15kg/m3 and coefficient of air flow, Cd as 0.75. Neglecting compressibility of air, calculate the suction at the throat.
10 M
2 (b)
Define the following terms and explain their significance. Also name the tests used to evaluate them for:
i) Constant speed
ii) Variable speed engines
iii) Indicated power
iv) Mechanical efficiency
v) Brake thermal efficiency
vi) Frictional power
i) Constant speed
ii) Variable speed engines
iii) Indicated power
iv) Mechanical efficiency
v) Brake thermal efficiency
vi) Frictional power
10 M
3 (a)
The following observations were made during a test on a diesel engine:-
Brake power of engine=31kW
Fuel consumption=10kg/h
Flow rate of cooling water=530kg/h
Rise in temperature of cooling water=50°C
Calorific value of fuel=44000kJ/kg
Exhaust gases are passed through an exhaust gas calorimeter. Flow rate of water through the calorimeter is 450kg/h and its rise in temperature is 40°C. Exhaust gases leave the calorimeter at 90°C. Assuming the engine used A/F ratio of 20:1. Prepare a heat balance sheet on minute basis and percentage basis.
Brake power of engine=31kW
Fuel consumption=10kg/h
Flow rate of cooling water=530kg/h
Rise in temperature of cooling water=50°C
Calorific value of fuel=44000kJ/kg
Exhaust gases are passed through an exhaust gas calorimeter. Flow rate of water through the calorimeter is 450kg/h and its rise in temperature is 40°C. Exhaust gases leave the calorimeter at 90°C. Assuming the engine used A/F ratio of 20:1. Prepare a heat balance sheet on minute basis and percentage basis.
10 M
3 (b)
Explain:
i) Octane number
ii) Cetane number
i) Octane number
ii) Cetane number
10 M
4 (a)
Determine the diameter of a fuel orifice for a four stroke engine which develops 15kW at 2000rpm. Fuel consumption is 0.24kg/kW-h of a fuel of 32°C API. The duration of fuel injection is 30° of crank rotation. Fuel injection pressure is 130bar and cylinder pressure is 45bar. Assume velocity coefficient 0.9 and specific gravity of fuel is given by the relation:-
10 M
4 (b)
Explain the function of any two with neat sketches:-
i) Air bleed jet
ii) Emulsion tube
iii) Anti-dieseling system
iv) Economiser system
i) Air bleed jet
ii) Emulsion tube
iii) Anti-dieseling system
iv) Economiser system
10 M
5 (a)
What are the objectives of supercharging? What are the limitations of supercharging? Explain the term charge cooling and how it is achieved in a turbocharged engine.
10 M
5 (b)
Explain the types of combustion chambers used in S.I. engines and compare them why the maximum diameter of S.I. engine combustion chambers is limited?
10 M
6 (a)
A fuel has the following percentage composition by mass:-
C=85%, H2=15%
Determine:
i) The stoichiometric mass of air required for complete combustion of fuel.
ii) The percentage composition by mass of dry products of combustion.
Air contains 23.2% oxygen by mass.
C=85%, H2=15%
Determine:
i) The stoichiometric mass of air required for complete combustion of fuel.
ii) The percentage composition by mass of dry products of combustion.
Air contains 23.2% oxygen by mass.
10 M
6 (b)
Explain with neat sketches the working of a battery ignition and magneto ignition and compare their advantages and disadvantages.
10 M
Write short notes on any four:-
7 (a)
Requirements of spark plug in S.I. engine with neat sketch.
5 M
7 (b)
Alternative fuels used in I.C. engines.
5 M
7 (c)
Wankel Engines.
5 M
7 (d)
MPFI for S.I. engines.
5 M
7 (e)
Engine cooling systems.
5 M
7 (f)
SAE ratings of lubricants.
5 M
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