X-Mozilla-Keys:                                                                                 
Russell Kent wrote:

Fred Moreno wrote:

1) The pump performance for an incompressible fluid depends only on the pressure
rise across the pump, not the inlet pressure, as long as the inlet is not
cavitating.  Cavitation is unlikely as long as the inlet is not restricted and
the water temperature is low (near ambient) since cavitation is a boiling
phenomenon, and you need very low pressures (a couple of inches of mercury) to
boil water at 60-70F.  Suck out of a bucket with a water level that is at or
above the pump inlet to help avoid cavitation, but mainly to get the pump primed
so it will start.  Control flow with a valve at the pump outlet, not the inlet.

I thought that cavitation was always a concern with boat & ship screws.  In fact, I
know the U.S. Navy has spent oodles of money on this problem becase even a tiny bit
of cavitation makes a very distinctive sound in the water, which is very bad for
submarines.  The water is plenty cold and unrestricted there...

Russell Kent

The Aircraft Rotary Engine Newsletter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org