At a high level, this is simple. Hot gas goes out the back, and Newton's third law says the engine is pushed forwards. But when you look inside the engine, it's less clear which part experiences the thrust. Compressor? Turbine? Combustion chambers? Nozzle? How about if there's an afterburner?
For other kinds of aircraft engine, this is comparatively easy to figure out:
- For a piston engine, the thrust is felt on the propeller blades, since they're doing the work on the air.
- For a turboprop, most of the thrust is on the propeller blades, and the residual jet thrust presumably works like a turbojet.
- For a turbofan, most of the thrust comes from the fan blades, and, again, the thrust from the hot core presumably works like a turbojet.
- For a rocket, some of it comes from pressure on the head of the combustion chamber, and the rest from the divergent part of the nozzle.
Reading about turbojet history, largely in Anthony Kay's books, has shown me that compressors sometimes pull forward and turbines backwards, but hasn't shown me any rules about this. How does it work?