How does a jet engine work? Let’s look inside
Mechanically minded folks are always curious exactly how something works, and occasionally, achieving that goal requires some drastic measures. I think I can safely say that anyone reading this has taken something apart to see which parts comprise it and observe how they interacted. In the pursuit of better understanding jet engines, YouTube channel Warped Perception created a miniature, see-through unit, and the model clarified a few things for me even before it fired up.
Jet engines are strange affairs if you are used to reciprocating engines, so I was happy to see Warped Perception start this video with a brief explainer of a jet engine’s basic parts and processes. Compared to an Otto cycle engine, the four strokes happen linearly, with a fan acting as an intake that forces fresh air into the “combustion chamber.” There, fuel is mixed and ignited, expanding and, as it exits, spinning a fan to draw in more fresh air. The thrust out the rear of the engine is the usable force.
In order to see what’s inside while the engine is running, the traditionally steel body of the jet engine needs to be replaced with something transparent and highly resistant to heat. While the video doesn’t specify the exact material, it appears to be a thick-wall glass tube sandwiched between two custom-made end pieces and sealed with silicone gaskets. Before final assembly, the rotating assembly is balanced to thousandth of a gram, which makes sense considering it needs to spin at nearly 100,000 rpm.
The real kicker comes at the end, when our fabricator host has the engine running and puts a smoke machine in front of the intake. Given the sound and fury coming from the little jet, and the speeds at which the pump fans are turning, you’d expect the engine to gulping in air, but it isn’t. As Warped Perception points out, thrust is generated not from air passing through but from the expansion of the fuel and air mixture as it burns.
Seeing it all in practice is pretty neat. The host says he wants to find a way to see even further into the engine while it is running, so we will be on the lookout for follow-up videos that might highlight the starting procedure specifically. Learning from a video is way more fun than reading a textbook, isn’t it?