[310toumad]

Hello,


I'm new to CFD and attempting to practice learning by setting up a simulation from a model of a gear pump I made. From looking around, there are not many tutorials on this subject. Most tutorials on rotating machinery involve centrifugal pumps. Even then, very few of them give instructions on how to manipulate the original, imported geometry to set it up for meshing which is a critical step. Usually the mesh has already been created. This was the case for the ONE tutorial on a gear pump I found on scribd after searching these forums.

That being said, I attempted (what I thought) would be the procedure for setting up a gear pump by performing several boolean operations. I want to provide a step by step account of this with screenshots to show what I did. My hope is for more experienced users to take a look and give feedback if something should have been done differently.

First step: Import pump assembly .x_t file into ANSYS. This is comprised of four bodies: Housing, end-plate, and two gears.

Second step: Perform unite boolean operation to join end-plate and housing as one body. Then, hide both gears and use fill command to extract internal volume of pump housing.

Third step: At this point I hide the pump housing. Rotating fluid zones need to be defined around the gears, so the only way I can see to do that is to create a sketch and extrude to form a cylinder around each gear and specify this as a "fluid" region in details of body palette.

Fourth step: I do a subtract boolean operation to separate the rotating fluid zones from the overall internal fluid region. This creates four separate fluid regions: the inlet and outlet stationary zones, and the two rotating regions.

Fifth step: Next I do another subtract boolean operation to remove the solid gear geometry from cylindrical, rotating fluid region surrounding it. Its my understanding that the cavity/empty space left behind represents the solid region of the gear.

Sixth step: At this stage I cannot see any further manipulation of the geometry that needs to be done (perhaps I'm wrong), so I move to meshing and just generate a mesh using default settings.

Seventh step: In the set up, I turn on mesh motion under cell zone conditions for the two rotating regions, and define the parameters for axis of rotation and RPM for each. Then I turn on dynamic meshing and create two dynamic mesh zones for the rotating fluid regions, and select the type as "deforming."

This is as far as I got. I tried to preview the mesh motion, but it didn't seem to work. One of the questions I have is that when I created the original mesh, there is a region where the two rotating fluid zones overlap. What I don't know is, is my mesh supposed to look like that going into set-up, or did I miss additional steps in prepping the model in design modeler? I wasn't sure if using the dynamic mesh option is supposed to account for the overlapping mesh region. When I look at other meshes of gear/lobe pumps, there doesn't appear to be an overlapping region at all. Some overall guidance would be helpful, thanks.

[310toumad]

Here are steps 6 and 7 and what my mesh looks like. Also, why is "motion attributes" greyed out when I try to define the two dynamic mesh zones?

[Dohany]

It's a interesting post. Could you manage to do it?