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Unread 05-27-2007, 10:19 AM   #253
bobo5195
Cooling Savant
 
Join Date: Aug 2005
Location: uk
Posts: 400
Default Re: How much pump is enough? How much is too much?

NB I have never actually seen a water cooling pump in the flesh. But have actually made one in my uni course (100mm diameter brass rotor with an ally body powered by a 200W motor, think the best were managing about 30% eff (real to actual hydraulic power) at 6 litres per minute and 10meters of head or something like that).

Those numbers seem reasonable. (hydraulic power (W) = delta P (pa) * Q (kg/m/s), Q being the mass flow rate).

Numbers are low due the pumps not avoiding restrictions and cavitations. Cavitation occurs due to the rotors action. At the start due to centrifugal action the water is moving slowly while at the end it is moving pretty fast. Also the flow channel is expanding. This means that you will get areas of gas build up inside the pump sucking the water backwards. Also the blade designs are often straight when you actually want to curl them so the water around. Same with the inlet where you want a nice little deathspike to smooth the flow around so the loss factor is lower.

I was thinking that I could do a nice little business in upgrading D5’s with a “tuning kit”, hehehehe
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