Resolving aerofoil tip curvature in CFX-mesh

Jenny

Hi,

I recently posted a query about negative pressure I was calculating in the run of a fan and have since resolved this problem, so thank you to the folk who responded to me.

I have since been trying to refine the mesh for further analysis and come up with a problem which I am hoping someone may be able to suggest an answer to. To explain the setup:

1. I have a hollow cylinder with a small chamfer on the top and a closed top which acts as a hub. In reality it is pressed onto a motor, hence the hollow inside. On the straight walls of the cylinder, again in reality, are glued a set of vanes. My CAD model was set up so the cylinder and blades were one unit. For the numerical work in CFX, I extruded the top of the hub to the bottom to basically fill it up, so the whole geometry was a closed surface.

2. Where the vanes are glued to the side of the cylinder, the contact area is in the shape of an aerofoil section. I am having untold difficulty in resolving the curvature at the top of the aerofoil shape. I've tried face spacing control on the cylinder, point control and line control with numerous edge lengths and radii. For some reason the mesh keeps cutting off the edge of the aerofoil tip and going back onto itself so I get errors related to the mesh intersecting and overlapping itself, or another about negative parametric volumes.

I am using CFX mesh and my mesh is composed of tets. I am trying to put inflation layers on the walls of the cylinder and vanes, but at this stage can't even get the surface mesh to work.

I have put up an image trying to show where the problem is occurring. I have circled in white the problem area. http://www.dezignit.com/hubproblem.jpg

I've exhausted everything I know to solve this and I'd appreciate any bright ideas anyone might have on a way to resolve this problem.

Best wishes, Jenny