Screw Compressor Simulation

Velocimetry · March 14, 2018, 14:57

I am trying to conduct fluid analysis on a screw compressor.
The design is something like in this video.

https://www.youtube.com/watch?v=Pu5YX_qIPVo

The video employed a TwinMesh meshing software and CFX solver to efficiently run the analysis.

Apparently, I do not have the TwinMesh Grid software, so I am stuck with ANSYS Meshing.

How would one mesh something like this in ANSYS so it will work for CFX.

I understand fluent has dynamic meshing, but what about CFX?

ghorrocks · March 14, 2018, 15:45

That simulation was likely done using immersed solids, not dynamic remeshing. There is a tutorial example of a screw compressor with immersed solids on the CFX tutorials (available from the ANSYS Customer webpage).

You can do this with dynamic remeshing. CFX supports this through an interface with ICEM. Again, examples are on the ANSYS Customer webpage.

ghorrocks · March 14, 2018, 15:45

That simulation was likely done using immersed solids, not dynamic remeshing. There is a tutorial example of a screw compressor with immersed solids on the CFX tutorials (available from the ANSYS Customer webpage).

You can do this with dynamic remeshing. CFX supports this through an interface with ICEM. Again, examples are on the ANSYS Customer webpage.

Velocimetry · March 14, 2018, 16:24

Quote:

Originally Posted by ghorrocks

That simulation was likely done using immersed solids, not dynamic remeshing. There is a tutorial example of a screw compressor with immersed solids on the CFX tutorials (available from the ANSYS Customer webpage).

You can do this with dynamic remeshing. CFX supports this through an interface with ICEM. Again, examples are on the ANSYS Customer webpage.

I did look over the customer portal of ansys. Could not find it. If you have a link or a search term, please send it.

Regarding dynamic remeshing, my problem is a super charger where the screws are rotating and compressing the gas. Can I get by sliding mesh? or am I stuck with dynamic remeshing?

Gert-Jan · March 14, 2018, 17:11

This is Twin Mesh. For sure.

With Twin Meshing tool from Berlin, you have to make a mesh for every degree of rotation and read these meshes in for each time step.
So there is quite some meshing to be done for one rotation of the twin screw. And a lot of bookkeeping. :-) But at least you can get it done.

Immersed solids is also a possibility but by far not as accurate as the twin mesh method. But if accuracy is not really necessary, you can get an idea of the flow using immersed solids. Not sure if you can combine it with compressible gas. But I think it will do.

Forget Dynamic meshing for this application. Not suitable. Not even in Fluent. Your gap is way too small. Sliding meshing is completely out of the question, since there is no sliding interface.

So, if you want this to be solved accurately, buy a license. Period. Or hire someone with a license. I don't sell it, nor have it.

fiko · April 10, 2018, 02:54

did you solve this problem? How? I have same problem now.

Velocimetry · April 10, 2018, 10:34

I did not. I lost the project, because I could not do it. If you come up with an answer, would appreciate sharing some tips

Gert-Jan · April 10, 2018, 10:40

Twin Mesh is the only succesfull solution I have seen so far.
Ánd I don't have it nor sell it.

March 14, 2018, 14:57	Screw Compressor Simulation	#1
Velocimetry New Member Join Date: Mar 2018 Posts: 14 Rep Power: 8	I am trying to conduct fluid analysis on a screw compressor. The design is something like in this video. https://www.youtube.com/watch?v=Pu5YX_qIPVo The video employed a TwinMesh meshing software and CFX solver to efficiently run the analysis. Apparently, I do not have the TwinMesh Grid software, so I am stuck with ANSYS Meshing. How would one mesh something like this in ANSYS so it will work for CFX. I understand fluent has dynamic meshing, but what about CFX?

March 14, 2018, 15:45		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,816 Rep Power: 144	That simulation was likely done using immersed solids, not dynamic remeshing. There is a tutorial example of a screw compressor with immersed solids on the CFX tutorials (available from the ANSYS Customer webpage). You can do this with dynamic remeshing. CFX supports this through an interface with ICEM. Again, examples are on the ANSYS Customer webpage. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

March 14, 2018, 15:45		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,816 Rep Power: 144	That simulation was likely done using immersed solids, not dynamic remeshing. There is a tutorial example of a screw compressor with immersed solids on the CFX tutorials (available from the ANSYS Customer webpage). You can do this with dynamic remeshing. CFX supports this through an interface with ICEM. Again, examples are on the ANSYS Customer webpage. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

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March 14, 2018, 17:11		#5
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,885 Rep Power: 27	This is Twin Mesh. For sure. With Twin Meshing tool from Berlin, you have to make a mesh for every degree of rotation and read these meshes in for each time step. So there is quite some meshing to be done for one rotation of the twin screw. And a lot of bookkeeping. :-) But at least you can get it done. Immersed solids is also a possibility but by far not as accurate as the twin mesh method. But if accuracy is not really necessary, you can get an idea of the flow using immersed solids. Not sure if you can combine it with compressible gas. But I think it will do. Forget Dynamic meshing for this application. Not suitable. Not even in Fluent. Your gap is way too small. Sliding meshing is completely out of the question, since there is no sliding interface. So, if you want this to be solved accurately, buy a license. Period. Or hire someone with a license. I don't sell it, nor have it.

April 10, 2018, 02:54		#6
fiko New Member Cemal Join Date: Apr 2018 Posts: 2 Rep Power: 0	did you solve this problem? How? I have same problem now.

April 10, 2018, 10:34		#7
Velocimetry New Member Join Date: Mar 2018 Posts: 14 Rep Power: 8	I did not. I lost the project, because I could not do it. If you come up with an answer, would appreciate sharing some tips

April 10, 2018, 10:40		#8
Gert-Jan Senior Member Gert-Jan Join Date: Oct 2012 Location: Europe Posts: 1,885 Rep Power: 27	Twin Mesh is the only succesfull solution I have seen so far. Ánd I don't have it nor sell it.