I'd like to get some clarification on a point Bill mentions. To the best of my understanding, centrifugal pump energy always increases with increasing flow. As the motor essentially runs at a constant RPM (not quite, but close), the motor efficiency should be comparatively constant.
If submerged, all pump energy gets into the water either directly as pressure*flow, non-effectual flow (turbulence), or thermal energy off the motor casing.
I believe the real answer is that energy drops with dropping flow, but energy does not drop as quickly as flow. Translation, less energy gets put in with decreasing flow, but the resulting delta-T due to the pump increases. ie, lower energy but more energy per unit volume of fluid pumped.
Thoughts?
Last edited by myv65; 09-17-2003 at 04:53 PM.
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