Correct Answer - Option 1 : increase specific output
Few main objectives of supercharging:
(i) To increase the power output for a given weight and bulk of the engine. This is important for aircraft, marine and automotive engine where weight and space important.
(ii) To compensate for the loss of power due to attitude. This mainly relates to aircraft engines which lose power at an approximate rate of one percent 100 metres altitudes. This is also relevant for other engines which are used at high altitudes.
(iii) To obtain more power from an existing engine.
The purpose of supercharging an engine is to raise the density of the air charge before it enters the cylinders. Thus, the increased mass of air will be inducted which will then be compressed in each cylinder. This makes more oxygen available for combustion. Consequently, more air and fuel per cylinder will be forced into the cylinder, and this can be effectively burnt during the combustion process to raise the engine power output to a higher value.
Purpose of supercharging:
- Provides better mixing of the air-fuel mixture
- Increase the volumetric efficiency
- Increase the power output of the engine
- It tends to increase the possibility of detonation in an S.I. engine and lessen the possibility of knocking in a C.I. engine