Sparked by this question:
Take any non-propeller powered aircraft, when idle, the sound produced by the engines are fairly low pitched, and as the engine spins up, increasing in pitch before becoming a full on roar.
I figured that the major sources of engine noise could be
- The air rushing out of the exhaust,
- The noise of combustion in the engine,
- The mechanical noise of engine parts
My question is what causes the majority of the engine noise at idle vs full power.
To stop this question being too broad, lets discount noise coming from any source that's not the engine's of the aircraft in question. I just want to know about engine noise.
I had a look at this question, but that doesn't have any information about the source of engine noise, just that the turbine itself will also produce noise which is something I didn't consider.