I.C Engines LAB VIVA Questions :-
1. What is IC ENGINE?
The internal combustion engine converts chemical energy into useful mechanical energy by burning fuel. Chemical energy is released when the fuel-air mixture is ignited by the spark in the combustion chamber. The gas produced in this reaction rapidly expands forcing the piston down the cylinder on the power stroke.
2. What are the Advantages and Disadvantages of using LPG in Car?
Advantages :
- Complete combustion
- Fuel saving
- Homogeneous combustion.
Disadvantages :
- As complete combustion is occurring, more heat liberated, not advised for long journey, engine will be over heated
- Installation is difficult
- Reduce engine life efficiency.
3. What is Scavenging?
Scavenging is process of flushing out burnt gases from engine cylinder by introducing fresh air in the cylinder before exhaust stroke ends.
4. What is meant by supercharging?
Supercharging is a method of increasing an engine’s power output, by forcing air into the engine under greater than atmospheric pressures. Supercharging usually refers to belt driven compressor (I.E. roots/screw or centrifugal), some early uses superchargers were driven directly off the crank shaft.
5. Why diesel Engine don’t have spark plug?
The compression ratio is high enough to combust the diesel without the aid of sparkplugs Answer Most diesel engines will have a ‘glow’ plug, this gives of enough heat to help get the engine started, the heat generated from the first few revolutions together with the compression from the piston is enough to ensure the engine keeps running. Some modern diesel engines no longer require a glow plug.
6. Which are the reference fuels for knock rating of S.I. engines?
n-heptane and ISO-octane.
7. Which pollutant is major greenhouse gas and what is its effect?
CO is major greenhouse gas and it traps the radiation of heat from the sun within earth’s atmosphere.
8. What are the important operational performance parameters in design of fuel firing equipment?
Fuel flexibility, electrical load following capability, reliability, availability, and maintenance ease.
9. How the analyses and calorific values of fuels can be reported?
It may be reported as
- As received or fired (wet) basis .
- Dry or moisture free basis.
- Combustible or ash and moisture free basis.
10. What is ATFT Technology used in Honda Hunk?
ATFT means Advance Tumble Flow Induction Technology,
Tumble flow means swirling. In this technology fuel air mixture from the carburetor into the engine cylinder with a swirl action. The advantage being one gets a more efficient burning of fuel hence more power and better fuel economy with lesser emissions.
More IC Engine VIVA Questions :-
1. The constant volume process in I.C. engines is characteristic of the _________.
2. Compression-ignition engines use liquid fuels of _______ volatility.
3. Compression ratio maybe of the order of 11.5 : 1 to 22 : 1 in case of _______.
4. Low CO and hydrocarbon emission occurs at low and moderate loads in case of_______.
5. A triangular rotor rotates on an eccentric shaft inside an epitrochoidal housing, the rotor tips being in constant contact with the housing and form three working chambers.
6. In case of aircraft engines, the power at 6100 m altitude is about_______% of the sea level wide-open throttle output for any given speed.
7. The stroke-bore ratio in case of aircraft engines in normally _________.
8. The spontaneous combustion or autoignition of an appreciable portion of the charge
9. A divided chamber construction, a combination of the precombustion chamber and the turbulence chamber design.
10. Early or late injection of fuel in the diesel engine results in _________.
11. Injection system which forces fuel through spray nozzle by hydraulic pressure.
12. It times, meters and forces the fuel at high pressure through the spray nozzle.
13. A restriction in the outer end of the carburettor to provide an extra rich air-fuel mixture for starting.
14. Used to produce gas-tight seal between the piston and the cylinder liners.
15. It takes care of the fluctuations or the cyclic variations in speed.
16. Closes one end of the cylinder and contains the inlet and exhaust valves.
17. A _______is a device used to diminish noise of the intake or exhaust.
18. The finished part of a shaft which rotates in or against a bearing is called_______.
19. An item made of thin layers.
20. The most effective knock suppressor.
21. Optimum spark advance is the timing which develops maximum
22. Higher concentrations of NO.,, are found in I.C. engines with_______compression ratio.
23. The principal source of exhaust carbon monoxide is_______.
24. Masses used for balancing purposes.
25. A device for atomising and vaporising the fuel and mixing it with air in varying proportions.
26. Used to step up 6 or 12 volts to high tension voltage of about 20 Kvolts.
27. The closed area formed by suction and exhaust operation in I.C. engines.
28. Ratio of brake power to indicated power.
29. The ratio of brake power output to the fuel energy input per unit time _________.
30. The ratio of the mass of the charge admitted during the suction stroke of the engine to the mass at normal pressure and temperature of the volume of the charge equal to piston displacement.
31. Ratio of the indicated thermal efficiency to the corresponding ideal air standard efficiency
32. The ratio of actual fuel air ratio and chemicall correct fuel air ratio.
33. Specific fuel consumption is minimum for fuel air ratio _________.
34. Mean effective pressure is maximum for fuel air ratio _________.
35. The mechanical efficiency of a multicylinder engine is determined by _______test.
36. The four stroke cycle is complete in _______revolutions of crankshaft.
37. For completion of four strokes, the cam shaft makes _______revolution.
38. Only air is sucked in during suction stroke.
39 operation in 4 stroke cycle petrol engine continues from 50° before bottom dead centre to 10° after top dead centre.
40. The thermal efficiency of diesel engine in comparison to petrol engine is ________.
41 _______ is used for obtaining required firing order in spark ignition engines.
42. Petrol engines employ governing.
43. Standard firing order for 4 cylinder petrol engine is _______.
44. Standard firing order for 6 cylinder petrol engine is _______.
45. Morse test is used for multicylinder spark ignition engines to determine
46. Auto-ignition reaction time for petrol-air mixture is minimum for relative fuel air ratio of _______.
47. The tendency to knock in C.I. engines increases with_______the cooling water temperature.
48. Iso-octane in a fuel for spark ignition engines auto ignition.
49. Normal heptane in fuel for spark ignition engines _______auto ignition.
50. The knocking in S.I. engines increases with _______in compression ratio.
51. Advancing the spark timing in S.I. engines _______the tendency for knocking.
52. Tendency to knock in S.I. engines and the cooling water temperature are related.
53. Ignition quality of fuel for S.I. engines is determined by_______number rating.
54. The petrol available commercially in the country has octane number of_______.
55. The diesel available commercially in the country has cetane number of_______.
56. The knocking tendency in C.I. engines increases with ______ of compression ratio.
ANSWERS::
1. spark ignition
2. low
3. C.I. engines
4. diesel engines
5. Wankel or rotary engine
6. 50
7. below 1.0
8. combustion knock
9. energy cell
10. loss of power
11. mechanical injection
12. injection pump
13. choke
14. piston rings
15. flywheel
16. cylinder head
17. muffler
18. journal
19. laminated
20. tetraethyl lead
21. torque
22. higher
23. rjch mixture combustion
24. crank webs
25. carburettor
26. ignition coil
27. negative loop
28. mechanical efficiency
29. thermal efficiency
30. charge efficiency
31. relative efficiency
32. relative fuel air ratio
33. less than one
34. greater than one
35. Morse
36. two
37. one
38. diesel engines
39. exhaust
40. higher
41. distributor
42. quantity
43. 1-3-4-2
44. 1-4-2-6-3-5
45. mechanical efficiency
46. unity
47. lowering
48. retards
49. accelerates
50. increase
51. increases
52. directly
53. octane
54. 80-85
55. 40-45
56. decrease