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centrifugal compressor map simulation-query

Question asked by Pradeep Kumar Srinivasan on May 23, 2018

Hi all,


I have a problem in simulating the centrifugal compressor problem. I will give a brief scenario of my setup. But before that,


Did I go through the previous post's? Yes, But wasn't that helpful/ the post is incomplete after few discussions

Did I go through the help file? Yes, and I am not sure about the pump efficiency as it should be unit less, but what they defined in equation goal is entirely wrong with what the efficiency equation is! There is some mistake here ( so helpfile is not helping anyway)


Model 1: Inlet mass flow rate with thermodynamic properties(Pr & Temp), outlet atm pressure to the expected value. The obtained outlet mass flow rate is of 23.4% less than the described inlet flow, which is wrong according to continuity equation. Also, the pressure ratio is 15% off (even after defining both inlet and outlet pressures) and so do the efficiency.

Model 2: Inlet Pressure and outlet mass flow rate. Problem is not solving and not giving any results.

Model 3: Pressure in and out, even though I don't like this B.C's, for the sake I tried it. The monitored output mass flow rate is twice as the expected value! Again it is wrong.

Model 4: Both inlet and outlet pressure are defined as same to see if there is an increase in the pressure due to the compressor input. There is a negative pressure (maybe suction, I don't understand this) drop across the impeller blade and more at the exit of the impeller.


All the models have the rotating region as per the KB suggested! ( Hope the model inside the rotating region will be considered as a solid).


Do I have experiment results? No, not so far! But I will have in the future.


How am I evaluating the results? Using the process flow calculation.


Yes, theoretical and numerical results do vary because the Pr.loss in the equipment are not considered. But it shouldn't be so much!


Any workaround or suggestions or something that could help me to move forward with my simulation? Unfortunately, I can't share the models because of confidentiality!


Looking forward to the replies.