Jet engines/turbines

Discussion in 'General Science & Technology' started by Edont Knoff, Apr 5, 2018.

  1. Edont Knoff Registered Senior Member

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    There is a point that makes me wonder since a while about jet engines. The pressure from the combustion should work in both directions, towards the compressor fan(s) as well as the exhaust side turbine.

    Why does a jet engine have a definite direction of self-sustained and even excess power rotation if the energy source is symmetric in the first place? The fans on both sides of the combustion area are similar ... is it the geometry of the combustion area and details in the fans? All the explanations that I googled did not explain that detail ...
     
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  3. exchemist Valued Senior Member

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    Yes. The resistance to the combustion gases exiting via the power turbine is a lot lower than that of pushing back through the compressor. You can get a sense of this by comparing the number of stages and the angles of the blades.
     
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  5. Edont Knoff Registered Senior Member

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    Thanks, that's good to know. I'll go back to study and look at the fans more closely. I hope I have the brains to make sense of it by myself, otherwise I'll ask again. My tries to build steam engines didn't work too well, guess the jet engine won't be much better

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    But I still want to understand how it need to be done to work.
     
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  7. sideshowbob Sorry, wrong number. Valued Senior Member

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  8. exchemist Valued Senior Member

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  9. Edont Knoff Registered Senior Member

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    I've actually tried to build one as a child, but I couldn't make my fuel explode in the needed way. (94% Ethanol). Maybe I should try again. I'll check that tutorial later. Thanks for the link!

    There have been model airplanes with that sort of engines. Forbidden now because of the noise.
     
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