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Old 08-27-2018, 12:50 PM   #79 (permalink)
kach22i
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Quote:
Originally Posted by freebeard View Post
My proposal most closely matches the 'gravitation water vortex' in Permalink #71. It is axial flow while the Francis turbine is centrifugal flow...............
Yes, and as I understand it axial flow is normally more efficient.

At least was the case for the early British jet engines of Frank Whittle (that did not use axial flow).

Go to about the middle of the page, I know this is apples to oranges comparison, but it's the best I can do for now.

https://en.wikipedia.org/wiki/History_of_the_jet_engine
Quote:
British aircraft engine designer, Frank Halford, working from Whittle's ideas, developed a "straight through" version of the centrifugal jet; his design became the de Havilland Goblin.

One problem with both of these early designs, which are called centrifugal-flow engines, was that the compressor worked by accelerating air outward from the central intake to the outer periphery of the engine, where the air was then compressed by a divergent duct set-up, converting its velocity into pressure.
It's the inherent redirecting energy at right angles that lowers the efficiency of centrifugal designs I do believe.

Some can argue that it's a trade off between velocity and pressure, but with water I don't think that's the case, as water is not compressible.
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