I feel a bit stupid for asking this, but I simply cannot wrap my head around how a jet engine directs its thrust backwards.
A piston engine opens and closes valves, such that air is alternately sucked in and compressed to create force. That makes sense and I understand how it works.
But with a jet engine there are no valves opening and closing, so why doesn’t the air that is sucked in just get pushed right back out from the thrust generated? How can an engine simultaneously suck in air from the front and force it out the back?
It makes no sense to me :-/
In: Engineering
The fan and turbine in the engine works to try to push everything in the right direction. Furthermore, the actual design of the engine itself makes it easier for flow to occur in one direction and not the other, encouraging everything to go in the right direction.
However things to go wrong, and without physical valves to prevent it, the flow goes backwards, this is known as a compressor stall. Notably this can be caused if the airflow into the engine is suddenly disrupted for some reason, which if you think about it makes sense. If for example, the engine’s airflow is suddenly and drastically reduced, there is then a lot less air for the fans in the engines to be pushing in “right direction”, which may result in the combustion overpowering the air being pushed in it’s way, allowing it to go “backwards”
They used to be more common (though not sure how common is “more common”) because older jet engines were obviously produced with older and less advanced understanding of making jet engines work. Luckily for us, they are much less common nowadays, and would likely mean there was already some damage with the engine.
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