Yes, you need to properly describe system. Diagrams are alway helpful.
Mike Cool
Mechanical Engineer
American Stainless Pumps, Inc.
Los Angeles California USA
www.aspumps.com
Bad bearings, lower voltage, high temperatures (not likely these days) furry animals crawling inside. VFD...
Mike Cool
Mechanical Engineer
American Stainless Pumps, Inc.
Los Angeles California USA
www.aspumps.com
Assume the impeller/propeller to be a perfect screw. Pitch times velocity (rpm) times area equals volume. Multiply slip factors (pulled from thin air), and you have flow rate against negligable head. In short, a good CFD run would probably shed better results, but knowing max capacity is...
They are insisting on MAX suction pressure because they want to make sure the pump is suitable to achieve MAX discharge pressure without breaking. Max dischare pressure includes max suction pressure. Your design suction pressure is ALSO required for properly selecting a pump to achieve desired...
If as you say, today's pump after refurbishment is the same as the new pump, the problem is not with the pump. You describe a 10% drop in flow, but you don't discuss the system head? Has it gone up? During the 9 years of operation, it's certain that your piping is somewhat fouled. This adds...
I was wrong in stating that two boundry conditions can be set at one inlet or outlet. What we do is set one boundry condition, and multiple surface goals at each inlet or outlet.
Mike Cool
Mechanical Engineer
American Stainless Pumps, Inc.
Los Angeles California USA
www.aspumps.com
Best of luck to you. If you get good results, please forward mesh setting details.
Mike.
Mike Cool
Mechanical Engineer
American Stainless Pumps, Inc.
Los Angeles California USA
www.aspumps.com
You can't know your accuracy until you get your results and compare to test data. It often goes both ways, +/-. Each engineer must perform their CFD studies, and compare to test data, then re-test with different mesh settings until you start to get close. That experience will allow you to...
Probaly closer to 300. I have never seen a good convergence beyone 1000, but you'd have to ask tech support on that one. I suppose it all depends on your mesh, given good constraints and goals.
We have had many sims blow up too, so you are in good company.
What are you trying to do, and why...
Yes, we get accurate results sometimes, but on greatly simplified models. I have just had to upgrade my system so I can study more complicated systems. I'm in the middle of that mess right now.
You can set two boundry conditions at one outlet. You could set both the discharge pressure and...
You are doing it backwards. You need to:
Set a suction and discharge pressure boundry conditions.
Your goal should be the flow rate.
At a particular differential pressure, you will get a particular flow rate.
If you want to set the flow rate, you must also set a dischare pressure, and then...
I'm a pump designer and manufacturer (www.aspumps.com). In testing our pumps to confirm design intent, we measure flow rate, total dynamic head, input voltage and amps, rpm, and torque. Some of these measurement are redundant, but they serve as comparable data, and some measurements are more...