Do a jet engine’s turbines actively pull air into the engine once the turbines begin to spin? (Both during the starter motor phase and also during flight at higher speeds)
And does the front half of the engine produce a substantial amount of drag as it is travelling at high speeds? (not including the thrust coming from the back)
If anyone could help it would be much appreciated!
*I’m thinking about axial and turbofan jet engines, but am curious about all types, *apart from pulse jets*
Cheers!
In: 3
Yes. There is loads of research being done to minimise the drag effect of jet engines.
Typically a turbofan on modern jets will be a high
-bypass ratio engine, meaning a high ratio of the air sucked into it won’t go through the engine core.
I can’t recall offhand but the CFM-56 is around 80% bypass, meaning only a small fraction of the air sucked in actually gets “used” by the engine. Most of it goes around the core, having been propelled by the intake fan and spat out the back as thrust.
The core of the engine is there to power the large fan. While there is of course some thrust from the expanding heated gasses of the “jet” the majority of the thrust is just the air. Think super efficient, self contained propeller. Not quite but the idea is solid enough.
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