Problems about streamline in the axial diffuser

starhunter521 · May 27, 2014, 13:51

Hi, all.
This is my simulation of one centrifugal compressor. The BC of inlet is 1 atm for total pressure, 288.15 K for total temperature, axial direction for flow direction, and the BC of outlet is 3.4 atm for static pressure. The rotating speed of impeller is 28000 rpm.
When I checked the results in the view of B2B in CFD-post, I found the streamline in the axial diffuser was curly (the right one)while the upstream streamline in the radial diffuser (the left one )looked normal. Has anyone got this problem before?

Thank you for reading my post.

ghorrocks · May 27, 2014, 20:05

Do you mean the ripples in the streamlines?

This could be a numerical artifact:
* Rerun with a finer mesh
* Converge tighter
* Better mesh quality

and see if it goes away.

OR it could be real. Turbulence transition looks somewhat like that.

May 27, 2014, 13:51	Problems about streamline in the axial diffuser	#1
starhunter521 New Member shaodong Join Date: Jun 2013 Posts: 4 Rep Power: 13	Hi, all. This is my simulation of one centrifugal compressor. The BC of inlet is 1 atm for total pressure, 288.15 K for total temperature, axial direction for flow direction, and the BC of outlet is 3.4 atm for static pressure. The rotating speed of impeller is 28000 rpm. When I checked the results in the view of B2B in CFD-post, I found the streamline in the axial diffuser was curly (the right one)while the upstream streamline in the radial diffuser (the left one )looked normal. Has anyone got this problem before? Thank you for reading my post.

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May 27, 2014, 20:05		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,852 Rep Power: 144	Do you mean the ripples in the streamlines? This could be a numerical artifact: * Rerun with a finer mesh * Converge tighter * Better mesh quality and see if it goes away. OR it could be real. Turbulence transition looks somewhat like that.