Centrifugal Compressor Surge Analysis

mikaeldomingo · March 18, 2020, 02:53

Hello guys,

I want to find surge line for the compressor I designed. I followed the method in the article below. Doi number for the article is : doi:10.4271/2015-01-1280.

https://sci-hub.tw/10.4271/2015-01-1280

In this method, mass flow outlet and pressure inlet boundary conditions are used and transient calculations are performed. Method says that you can find the surge starting point for a speedline by reducing mass flow outlet boundary condition steadily with a constant slope as you can see in the attached figure 1.

Method follows that criteria for surge start is increase in pressure ratio flactuations and reach 0.05 standard deviation in average pressure ratio value. You can see the figure about this criteria at attached file 2.

I followed the method described. However, I could not get satisfactory results and I am not sure if this method is true or not.

What is your opinion about this method ? Is there anybody to perform surge analysis on CFX ? Which method did you follow ?

Thanks in advance,

Best regards.

ghorrocks · March 18, 2020, 06:18

I don't click on links to strange websites. Post images and text files as attachments directly to the forum.

Have you read the CFX Best Practises Guide? I think it describes the CFX recommended way of doing this.

mikaeldomingo · March 18, 2020, 06:37

Hi, I attached images as thumbnails, but I could not attach pdf due to oversize. So, I added doi number of the article.

ghorrocks · March 18, 2020, 18:18

The best way to answer your question is to do some research. I recommend you have a look in the CFX Reference manual for the best practises guides as that contains the recommended approach for many simulations. Also do a search of the CFX documentation on "surge", I think you will find some references you will be interested in looking at which show alternate approaches.

In other words, RTFM.

mikaeldomingo · March 19, 2020, 01:20

I read the manual. However, my question is not explicitly answered in the manual. I found some articles which each of them suggest different approaches. As you know, transient simulations take lots of time so that I cannot try all of them. That is why I write here. Perhaps, there is someone in this forum who is/was interested in surge phenomena that I could benefit. That is how know-how transfered.

Thanks for your reply.

mohamadlebron · April 7, 2020, 06:19

hello
you'd better to use average static pressure in outlet near the choke masss flow rates and use outlet mass flow rate near the surge points.

March 18, 2020, 06:18		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	I don't click on links to strange websites. Post images and text files as attachments directly to the forum. Have you read the CFX Best Practises Guide? I think it describes the CFX recommended way of doing this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

March 18, 2020, 18:18		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	The best way to answer your question is to do some research. I recommend you have a look in the CFX Reference manual for the best practises guides as that contains the recommended approach for many simulations. Also do a search of the CFX documentation on "surge", I think you will find some references you will be interested in looking at which show alternate approaches. In other words, RTFM. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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March 18, 2020, 06:37		#3
mikaeldomingo New Member Mikael Join Date: Nov 2019 Posts: 9 Rep Power: 7	Hi, I attached images as thumbnails, but I could not attach pdf due to oversize. So, I added doi number of the article.

March 19, 2020, 01:20		#5
mikaeldomingo New Member Mikael Join Date: Nov 2019 Posts: 9 Rep Power: 7	I read the manual. However, my question is not explicitly answered in the manual. I found some articles which each of them suggest different approaches. As you know, transient simulations take lots of time so that I cannot try all of them. That is why I write here. Perhaps, there is someone in this forum who is/was interested in surge phenomena that I could benefit. That is how know-how transfered. Thanks for your reply.

April 7, 2020, 06:19		#6
mohamadlebron New Member mohamadbaghdadi Join Date: Jun 2017 Posts: 2 Rep Power: 0	hello you'd better to use average static pressure in outlet near the choke masss flow rates and use outlet mass flow rate near the surge points.