THEORY OF A JET/ GAS ENGINE

Theory behind the jet engine as the ballon theory : when you let air out of a balloon , a reaction propels the balloon in the opposite direction ( this is the practical application of Newton third law of motion) .

Jet engines adopted the principle of taking a small mass of air and expelling it at an extremely high velocity .

A Jet engine is unsuitable as an aircraft power plant because it is incapable of producing thrust at low speed , it requires a forward motion itself before it produces any thrust .

Gas turbine engines have evolved into taking a large mass of air and expelling it at relatively slow speed velocity .

The Gas turbine engine has avoided the weakness of the jet engine by introducing a turbine driven compressor that produces thrust at slow speed

Therefore the aircraft power plant is the Gas turbine engines .

How is the Gas turbine enging work?

Gas turbine engine Is essentially a heat engine using air as a working fluid to provide thrust by accelerating air through the engine and increasing its kinetic energy .

To increase and maintain this kintic energy it passes through 3 steps :

1- Compressor : this will increase the pressure energy.

2- Combustion chamber : by adding heat energy

3- Exhaust: this will provide extra shaft power to either drive a conventional frontal fan to compress extra air to provide more jet flow , then finally exhausted through the exhaust nozzle .

By Captain / Shebl

FAA CFI,CFII AND MEI