I can roughly understand the working of an axial flow gas turbine i.e. the fluid moves over the blade and gets redirected, its whirl velocity component changes and the blade is pushed in the opposite direction.But I couldnt understand the working of a table fan or an aircraft propeller.I know that its the opposite of an axial flow gas turbine but couldnt really imagine it.Please explain the principle?
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$\begingroup$ it is not the opposite of an axial flow turbine. they work on exactly the same principles. $\endgroup$– niels nielsenDec 31, 2018 at 19:24
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$\begingroup$ @niels nielsen I just meant the energy transfer is in the opposite direction i.e. fluid to blade(turbine) and blade to fluid (compressor, fan, pump,etc..) $\endgroup$– user17332Jan 1, 2019 at 0:15
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$\begingroup$ OK thanks for that Mohan and happy new year to you $\endgroup$– niels nielsenJan 1, 2019 at 1:49
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$\begingroup$ @niels nielsen Thank you sir.Happy new year. $\endgroup$– user17332Jan 1, 2019 at 2:44
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1 Answer
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A table fan or a plane propeller have blades, pitched into an angle, which cuts into stationary air and acelerates it forward.
They are basically rotating wings, but working in reverse sense. Wings move up and create lift when wind goes through them. Fans and proppellers go through the air and cause it to move.
In a moving car if you hold your hand out of the window and try to keep your open hand like a row but gently angled you feel the pressure of the air trying to lift your arm up, and if you resist it you feel you are pushing the air down. And you may wish you had bigger hands to fly with.
A fan does the exact thing, by moving through the air in a screwdriver motion, it pushes it forward.
Or you could imagine tiny stationary air bubbles being plowed through by the blade and proppeled by the slant on the surface of it.
