Aeronautical Engineering/Jet engine

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Question
How does a jet engine work ?I've seen many videos and all say that the fan sucks in air and then the compressor squeezes it and the combuster burns and explodes leading to a strong jet of heated and expanding air that gives thrust. this energy then runs the turbine which again runs the fan . how can the same turbine run the fan when the fan is actually providing the energy to run the turbine ? i just don't understand the mechanism. I'm actually looking forward to build a miniature. any help would be appreciated . thank you !

Answer
I can understand your confusion. I once pondered the same question :)

Perhaps the easiest way to see where the energy is coming from is to use a balloon instead of a jet engine.

So, we take a large balloon and have a tiny amount of air (1/2 liter) in it and add a drop of gasoline, then explode it. What happens? The balloon expands a huge amount (lets say it expands to 10 liters or 20x original volume).

OK... Now lets take the same example and add a turbine at the balloons nozzle. We create a huge explosion that expands to 10 liters. All we have to do to keep the explosions continuous is to have the 10 liters of air rushing past the turbine pull in 1/2 liter of new air for the next explosion - and that is very reasonable for it to do.

What we have done is taken a drop of fuel the size of a bean and converted it to a volume of gas 1000,s of times larger. We then use the large amount of expanded gas to draw in just a little bit of air and do it again.

If you understand how a car engine works, a jet is exactly the same except a car does things over and over in cycles. A jet is a continuous single cylinder engine.

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Jan Zumwalt

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