Question

thermo II question

A jet engine does not produce shaftwork; how is power produced?

Answer 1

In jet engine power produces as follows.

The first part is compressor. The compressor sucks the air & compresses it. This highly compressed air is then forced into combustion chamber.
Then the Multiple nozzles inject fuel into the air & igniter(similar to spark plug) causes air to catch fire. The fuel then burns with oxygen present in compressed air which produce hot expanding gases.
These gases are passed through the turbines which causes the blades to rotate. This turning of turbine also rotates the shaft to which it is fixed. The same shaft in turn rotates the compressor. Which means instead of just letting out those hot gases, they are indirectly used to suck fresh air at the same time. This is the reason we need turbine after the combustion chamber section.
After coming out of the turbine, then the gases are allowed to exit the engine through a converging shaped nozzle.
The force of the exhaust gases pushing backwards(action) produces equal & opposite forward force(reaction)(Newton’s third law of motion). We call this forward force as thrust which powers the aircraft or vehicle forward.