Propulsion systems Flashcards
Piston engines
Used for small commercial aircraft (the cyclinders are flat, linear to each other). The engine does not offer same performance as turbine but are powerful enough for small commercial applications and very cheap. Some high performance piston engine planes use turbochargers.
Turbojet
Jet engines use compressors to compress intake air which then is mixed with the fuel mixture. Then the air/fuel mixture is combusted which rushes air out of the end of the jet engine providing thrust.
Turboprop
Turboprop operates with a jet engine in the middle too but with a turbine to power the compressor and drive the propeller. The gases expelled from the jet engine is used to drive the turbine (and hence the prop)
Turboshaft
Turboshaft engines utilise same operation as turboprop with jet engine with a prop powering a compressor and turbine. Turboshaft utislises the same mechanism but has another shaft coming off of the engine to create 2 outputs. This could be seen with helicopters with the main rotor and the tail rotor coming from the same engine.
Turbofan
Same as the turbojet but with the main differnce of having the turbojet shrouded in a cover of which has air bypass ducts. The turbojet produces exhaust gases which turn a rotor, connecting a shaft to the large fan in front. The large fan spins from the exhaust gases which captures lost energy and then the air bypass ducts can allow for more thrust to be generated from the large fan. This is in every jetliner today
Ramjet
The shape of the engine compresses the entering air, which is heated due to the compression. Then fuel is injected and the air/fuel mixture is lit up. THe expanding gases are forced out the nozzle at the back to produce thrust. However, this jet engine can only work in high speeds and not from standstill.
Scramjet
Scramjet operates similarly to ramjet but the airflow through the scramjet will be supersonic. This allows scramjet to operate effectively above speeds of Mach 3.
