This has really got me confused lately. I’ve read online that it increases efficiency, the potential energy of the air and helps with combustion, but my question is:
If the same amount of air is passing through the engine regardless, why pressurise it? Wouldn’t the gain in PE of the air just be equal to the loss of KE of the aircraft due to the air hitting/dragging the aircraft back as it’s compressed? I’m almost certain I’m wrong here, but any explanation which could clear this up for me would be great thanks.
In: 12
Because we add fuel to it at that stage, and the engine is created to have a lower pressure after the burners so the air expands in that direction gaining a lot of speed, driving a few turbines to help the engine keep going, then being ejected at high velocity out of the engine.
In the turbine engine first we have a fan, collecting air (it all sits on a single shaft, just to make it easy.
Then we have compressor stages, slowing the air down. But now we have more air in the same volume being injected into the burners where its mixed with fuel and ignited.
The air heats up so it wants to expand, or rather that is what hot air does, the molecules have a higher velocity. So they go to where the low pressure is which is after the burners where they bump into some fans driving the rest of the engine.
(the compressor stage may consist of up to 9 turbo fans, the driving stage usually just 3-4 powering the fan and the compressor stages) This is because the air is moving so much faster after the fuel has been burnt and everything is hot.
So we need the compressor stage to burn enough fuel to make all that happen.
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