[EmersonKB]

Hi,

As part of my final year engineering project, I am comparing the performance of a number of supercharger intake plates. Specifically I am looking at the intake plates of twin helical screw type compressors, similar to that shown below.





Initially I developed a 3D model of the intake plate using Solidworks.





Now the geometry actually a number of webs which branch from the bearing housings out to the plate itself. These webs include quite complex geometry due to the profiling on the underside. This results in a face which not only joins the bearing housing tangentially, but also tapers down to zero width at the same time. This is best described with a picture,



The plane was to (as a simplified flow model), model flow through a simple geometry matching the outline of the intake plate, with the plate removed from this geometry using a boolean cut opeartion. Again, this is made clear with a screenshot where the green geometry will be the flow region and the grey body is the plate which will be cut from this geometry.



Resulting in the following geometry,



This 3D model was exported for use in CFX via the Parasolid file format. Initially I had a lot of trouble getting CFX-Mesh to work with this geometry as whenever I selected 'Verify Geometry' or 'Generate Surface/Volume Mesh', the program would display 'Waiting for meshers to start...' for a long period of time and would not progress.

After extensive trial and error I decided the cause of this was poorly structured topology in the parasolid file. Using the program CADFix, I was able to restructure the parasolid files to a point where CFX would happily generate a mesh for the geometry.

After dealing with a few expected problem sliver faces and short edges, I was able to generate meshes with good resolution along the intake plate surface as well as inflation layers surrounding the plate and flow region walls to help resolve boundary layer flows.







However, the resulting volume mesh contains 800,000 elements. This seems very high and will result in long solution times. In addition to this I am not yet sure if my mesh is fine enough and may infact need (many) more elements.

I am after some guidance as to whether I am approaching this problem the right way.

Is there a more suitable method of modelling the flow then the boolean cut geometry I am currently using?

Is there a better way to deal with CFX freezing on 'Waiting for meshers to start' then using CADFix?

Is there a more suitable meshing method/application I should use?

I find there is a very limited amount of tutorials regarding the ANSYS Workbench/CFX workflow process and the tutorials that do exist deal almost entirely with 'perfect'/'ideal' geometry. Also there seems to be very little published literature where flow through complex 3D geometry has been simulated.