The power output of an engine depends up on the amount of air indicated per unit time, the degree of utilization of this air and the thermal efficiency of the engine. The amount of air inducted per unit time can be increased by increasing the engine speed pr by increasing the engine speed or by increasing the density of air intake. The method increasing the inlet air density, called supercharging, is usually employed to increase the power output of the engine. This is done by supplying air to a pressure higher than the pressure at which the engine naturally aspirates air from the atmosphere by using a pressure boosting device called a super charger.
OBJECTS OF SUPERCHARGING
The increase in the amount of air inducted per unit time by supercharging is obtained mainly to burn a greater amount of fuel in a given engine and thus increase its power output. The objects of supercharging include one or more of the following.
1. To increase the power output for a given weight and bulk of the engine. This is important for aircraft, marine and automotive engines where weight and space are important.
2. To compensate for the loss of power due to altitude. This mainly relates to aircraft engines which lose power at an approximate rate of one percent 100 meters altitude. This is also relevant for others engines which are used at high altitudes