AT6301 Automotive Engines Nov Dec 2016 Important Questions

Anna University Chennai - Important Questions of AT6301 Automotive Engines
B.E/B.TECH DEGREE EXAMINATION NOV / DEC 2016
Third Semester
Department of Automobile Engineering
AT6301 Automotive Engines
Nov Dec 2016 Important Questions
(Regulation 2013)

AT6301 Automotive Engines - All Important 16 Marks and 2 Marks Questions

AT6301 - AUTOMOTIVE ENGINES – QUESTION Important Questions 2 Marks and 16 Marks
UNIT I: CONSTRUCTION & WORKING PRINCIPLE OF IC ENGINES
Part A
1. State the application of CI engines?
2. What is Cubic capacity of an engine?
3. What is the purpose of gudgeon pin?
4. What is the speed ratio of cam shaft to the crankshaft?
5. What is clearance volume?
6. What is swept volume?
7. What is compression ratio?
8. What is stroke length?
9. What is square engine?
10. What is under square engine?
11. What is over square engine?’
12. What is radial engine?
13. Write the drawbacks of two stroke engine?
14. Write the advantages of two stroke engine?
15. Write the purpose of PV diagram?
16. What do you mean by pumping loss?
17. What do you mean by Frictional losses?
18. Define: Firing order
19. Define: Thermal efficiency
20. What is mean effective pressure?
21. What is piston clearance?
22. What is piston pin clearance?
23. What is ovality?
24. Write the purpose of Compression ring?
25. Write the purpose of Oil ring?
26. Write the purpose of connecting rod?
27. What is piston? By what material is made of? State why.
28. What is heat engine?
29. Which is heavier engine CI or SI? State why.
30. Classify the engine with cylinder arrangement?
31. Differentiate Wet liner and Dry liner
32. What is the purpose of liner?
33. Write the advantages of V type engine?
34. What is rotary engine?
35. Which engine has maximum thermal efficiency?
36. Write the formula thermal efficiency of Otto cycle?
37. Write the formula thermal efficiency of Diesel cycle?
38. Write the formula thermal efficiency of Dual cycle?
39. What is Damper?
40. Which is bigger in size, the exhaust valve or intake valve?
41. What is reversible engine?
42. What is power to weight ratio?
Part B
1) Compare two stroke engine and four stroke engine with regard to power output and thermal
efficiency?
2) Briefly explain the working principle of four stroke SI engine?
3) Briefly explain the working principle of four stroke CI engine?
4) Briefly explain the working principle of two stroke SI engine?
5) Briefly explain the working principle of two stroke CI engine?
6) Compare the SI engine and CI engine
7) Compare the two stroke and four stoke engine?
8) Classify the engine with various parameters?
9) Write the major difference between Otto cycle and Diesel cycle?
10) Find the derivation to calculate the thermal efficiency and the Mean effective pressure of Otto
cycle?
11) Find the derivation to calculate the thermal efficiency for Constant Pressure heat addition cycle?
12) Derive the thermal efficiency for Dual Cycle?
13) An air standard dual cycle has a compression ratio 9.5:1. The pressure and temperature at
beginning of compression are 1 bar and 25°C. Maximum pressure reached is 38 bar and the
maximum temperature is 1300°C. Determine work done per kg of air and cycle efficiency. Take
Cp=1.0004 KJ/Kg.K and Cv=0.717 KJ/kg.K for air (April 2012)
14) In an Otto cycle air at 17°C and 1 bar is compressed adiabatically until the pressure is 18 bar.
Heat is added at constant volume until the pressure is 42 bar. Calculate the air standard
efficiency, the compression ratio and the mean effective pressure for the cycle. Assume Cv =
0.717 kJ/kg K and R = 8.314 kJ/kmol K
15) In an SI engine working on the ideal Otto cycle the compression ratio is 6. The pressure and the
temperature at the beginning of compression are 1.013 bar and 27°C respectively. The Peak
pressure is 30 bar. Determine the pressure and temperature at the salient points, the air standard
efficiency and the mean effective pressure. Assume γ = 1.4 (Nov 2011)
16) A gas engine operating on the ideal otto cycle has a compression ratio of 6:1. The pressure and
temperature at the commencement of compression are 1 bar and 27°C. Heat added during the
constant volume combustion process is 1170 kJ/kg. Determine the peak pressure and temperatue
and work output per kg of air and the air standard efficiency. (April 2010)
17) In an Otto engine, pressure and temperature at the beginning of compression are 1 bar and
37°C respectively. Calculate the theoretical thermal efficiency of this cycle if the pressure at the
end of the adiabatic compression is 15 bar. Peak temperatue during the cycle is 2000 K.
Calculate (i) the heat supplied per kg of air (ii) the work done per kg of air and (iii) the pressure
at the end of adiabatic expansion. Take Cv=0.717 kJ/kg K and γ = 1.4
18) In an Ideal diesel cycle, the pressure and temperatue are 1.013 bar and 27°C respectively. The
maximum pressure in the cycle is 47 bar and the heat supplied during the cycle is 545 kJ/kg.
Determine (i) the compression ratio (ii) the temperature at the end of compression (iii) the
temperature at the end of constant pressure combustion and (iv) the air standard efficiency.
Assume γ = 1.4 and Cp = 1.004 kJ/kg K for air. (April 2011)
19) An ideal Diesel cycle operates on a pressure of 1 bar and a temperature of 27°C at the beginning
of compression and a pressure of 2 bar at the end of adiabatic expansion. Calculate the amount of
heat required to be supplied per kg of air if the ideal thermal efficiency is taken as to 60%. Take
Cv=0.717 kJ/kg K
20) A Diesel cycle operates at a pressure of 1 bar at the beginning of compression and the volume is
compressed to 1/15 of the initial volume. Heat is then supplied until the volume is twice that of the clearance volume. Determine the mean effective pressure. Take γ = 1.4
21) In a dual cycle the compression ratio is 10 and the maximum pressure is limited to 70 bar. If the
heat supplied is 1720 kJ/kg. Find the pressure and temperature at the various salient points of the cycle and cycle efficiency. The pressure and temperature at the commencement of compression are 1 bar and 100°C respectively. Assume Cp=1.004 kJ/kg K and Cv = 0.717 kJ/kg K for air. (April 2010)
22) An engine working with dual cycle has a compression ratio of 10 and 2/3 of heat of combustion
is liberated at constant volume and the remainder at constant pressure. The pressure and temperature at the beginning are 1 bar and 27°C. and the maximum pressure is 40 bar. Find the temperature at the end of compression and expansion. And the air standard efficiency. Assume γ
= 1.4 (Nov 2010)
23) A diesel cycle operates at a pressure of 1 bar at the beginning of compression and the volume is
compressed to 1/15 of the initial volume. Heat is then supplied until the volume is twice that of the clearance volume. Determine the mean effective pressure. Take γ = 1.4
UNIT II -- FUEL SYSTEMS FOR SI AND CI ENGINES
Part A
1) What is stoichiometric or chemically correct ratio?
2) What is the purpose of carburetor?
3) What is constant vacuum carburetor?
4) What is constant choke carburetor?
5) What is choke valve?
6) Define: Idling system?
7) Why the idling system needs rich mixture?
8) What is venture? How it assists for better carburetion?
9) What is equivalence ratio?
10) Write the various types of carburetor?
11) Write the disadvantages of carburetor?
12) What is distributor pump?
13) Write the classification of solid injection system.
14) Write the purpose of governor?
15) Write the classification of nozzle?
16) What are the advantages of multihole nozzle?
17) What is the advantage of Pintle nozzle?
18) What is unit injector?
19) What is Feed pump or transfer pump?
20) What is CRDI?
21) What is dripplilng?
22) What is calibration of injection pump?
Part B
1) Explain the working principle of Simple carburetor?
2) Explain the working principle of Constant vacuum type carburetor?
3) Explain the air fuel ratio requirements with the emission?
4) Explain the working principle of Distributor pump?
5) Explain the working principle of Jerk type pump?
6) Explain briefly about Pintle and Multihole nozzle?
7) Explain with neat sketch about common rail diesel injection system (CRDIS)
8) Explain the working of Unit injector?
9) Explain with neat sketch about the working principle of Simple mechanical governor?
10) A simple jet carburetor is required to supply 4.6 Kg of air per minute. The pressure and
temperature of air are 1.013 bar and 25°C respectively. Assuming flow to be isentropic and
compressible and velocity co-efficient as 0.8. Calculate the throat diameter of the choke for air
flow velocity of 80 m/s. (April 2012)
11) A simple jet carburetor is required to supply 5 kg of air and 0.5 kg of fuel per minute. The fuel
specific gravity if 0.75. The air is initially at 1 bar and 300 K. Calculate the throat diameter of the
choke for a flow velocity of 100 m/s. Velocity coefficient is 0.8. If the pressure drop across the
fuel metering orifice is 0.80 of that of the choke. Calculate orifice diameter assuming Cdf=0.60
and γ = 1.4 (Nov 2011)
12) A simple carburetor is designed to supply 6 kg of air per minute and 0.4 kg of fuel per minute.
The density of the fuel is 770 kg/m3. The air is initially at 1 bar and 17 C. Calculate the venture
throat diameter if the velocity of air at throat is 100 m/s. Assume Cda=0.84. Cdf=0.65 and γ=1.4.
If the pressure drop across the fuel metering orifice is 0.85 of the pressure at the throat.
(April 2010)
UNIT III COMBUSTION IN SI AND CI ENGINES
Part A
1) What is Homogeneous mixture?
2) What is Heterogeneous combustion?
3) What is Flame front propagation?
4) Name the various factors affecting the flame speed?
5) What is turbulence?
6) Write the method of increasing the turbulence?
7) What is abnormal combustion?
8) What do you mean by Knocking in SI engine?
9) What is Octane rating?
10) What is Octane number?
11) What is air swirl?
12) What do you mean by ignition lag?
13) What is delay period?
14) What is Pre-ignition?
15) What do you mean by squish motion?
16) What is surface ignition?
17) What are the different air motions created in CI Engines?
18) What is motoring?
19) What is open or direct combustion chamber?
20) What is indirect injection chamber or Auxiliary combustion chamber?
21) Define: Air-cell chamber
22) What is Swirl chamber?
23) What is precombustion chamber?
24) Write the disadvantages of indirect injection chambers?
25) Write the advantages of indirect injection chambers?
26) Mention the three zones of combustion in SI Engine combustion chamber?
27) Mention the Stages of combustion in CI Engine combustion chamber?
28) Write about the Rapid or uncontrolled combustion?
29) What is Cetane number?
Part B
1) Compare the Knock in SI Engine and CI Engine?
2) Explain briefly the process of knocking combustion in a SI Engine?
3) Explain briefly the Stages of combustion in SI Engine?
4) Explain briefly the Stages of combustion in CI Engine?
5) Explain briefly the process of knocking combustion in a CI Engine?
6) Briefly explain about the ignition timing with respect load and speed?
7) Briefly explain about various types combustion chamber designed for SI engines?
UNIT IV: SUPER CHARGING, TURBO CHARGING & ENGINE PERFORMANCE
Part A
1) What is naturally aspirated engine?
2) What is supercharged engine?
3) What is supercharging?
4) What is Turbo charging?
5) Mention the effect of supercharging?
6) What is supercharger?
7) Write the limitations or drawbacks of supercharging?
8) Why the cooling after compressing is necessary in supercharging?
9) What is blow down period?
10) What you meant by degree of supercharging?
11) What is turbo lag in turbocharging?
12) What is ram effect?
13) What is waste gate control in the turbocharger system?
14) Write the classification of dynamometers?
15) What is thermal efficiency?
16) What is Indicated thermal efficiency?
17) What is brake thermal efficiency?
18) What is brake mean effective pressure?
Part B
1) Explain : Supercharging
2) Explain : Turbo charging with waste gate, variable geometry
3) Explain : Engine Testing Standards
4) Briefly explain about the Hydraulic Dynamometer?
5) Explain about the Turbocharging methods?
6) Briefly explain about the Eddy current Dynamometer?
7) Explain : Engine performance maps
8) The following particulars were obtained in a trial on a four stroke gas engine:
Duration of trial = 1 hour, Revolutions = 14000, Number of missed cycle = 500, Net brake load
= 1470 N, Mean effective pressure = 7.5 bar, Gas consumption = 20000 liter, L.C.V. of gas at
supply conditions = 21 KJ/Liter, Cylinder diameter = 250 mm, Stroke = 400 mm, Effective
brake circumferences = 4 m, Compression ratio = 6.5:1 Calculate
i) Indicated power ii) Brake power iii) Mechanical efficiency iv) Indicated thermal efficiency

UNIT V: COOLING AND LUBRCATION SYSTEM
Part A
1) Why the cooling system is necessary in a vehicle?
2) Mention the different types of cooling system?
3) Write the characteristics of the cooling system?
4) Write the drawbacks or limitation of air cooling system?
5) Write the advantages of air cooling system?
6) Write the advantages of liquid cooling system?
7) Write the limitations of liquid cooling system?
8) What is thermostat?
9) Write the different properties of coolant?
10) What is thermosyphon cooling system?
11) What are the advantages of thermosyphon type cooling system?
12) Write the limitation of thermosyphon cooling system?
13) What is forced circulation cooling system?
14) What is pressurized cooling system?
15) Why the lubrication system is necessary in a vehicle?
16) Mention the different types of lubrication system?
17) What is dry sump lubrication?
18) What is wet sump lubrication?
19) Write the properties of lubricant?
20) Name the additives of lubricant?
21) Two-stroke engines need higher lubrication system, why?
22) What are the causes of overheating and overcooling?
Part B
1) Explain the requirements of lubrication system?
2) Briefly explain with neat sketch about the pressurized lubrication system?
3) Explain about wet sump lubrication system?
4) Briefly explain with neat sketch about the Splash type lubrication system?
5) Briefly explain with neat sketch about the Dry sump lubrication system?
6) Explain about Mist type lubrication system?
7) Explain about properties of lubricants?

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