Week 3 Challenge : CFD meshing on Turbocharger

Week 3 Challenge: CFD meshing on Turbocharger

AIM:

For the given model, check for the geometrical errors to make appropriate volumes. Create and assign PIDs and, perform surface mesh with the given target lengths as per PIDs.

1. Blade stage-1 = 1 mm
2. Blade stage-2 = 1 mm
3. Impeller = 2 mm
4. Shaft rotor = 1 mm
5. Turbo casing = 5 mm
6. Compressor casing = 5 mm
7. Inlet casing cover = 5 mm

Perform Volumetric mesh for the required volumes.

GIVEN MODEL:

Side View

Top View

Bottom View

Front View

Isometric View

Unshadowed Iso-view

TOPO Cleanup Procedure:

• As we see the model given has many single cons, we want to do some Geometry checks to explore what are the errors we are encountering here,
• SINGLE CONS- the edge which is shared by only one surface.
• DOUBLE CONS- the edge which is shared by two surfaces.
• TRIPLE CONS- the edge which is shared by three surfaces.

• And the model has some overlapped surfaces which have to delete to reduce the error during the meshing process.
• We have to check the triple cons also, in which region they are needed or not.

While performing a geometry check in the given geometry, we are getting multiple errors such as triple and single cons, overlapping surfaces as we discussed above,

• And the errors are highlighted in white color as shown in the below picture.

• As we have to remove the errors from the geometry to proceed with the meshing process, we have multiple tools to do so.
• First, we will see, how to delete the overlapped surfaces.
• Use the universal delete option to delete the surfaces.
• Enable the cross-hatches option in the geometry to select the surface easily which we want to delete.
• Use the PIDs selection tool to select a complete region in one shot, after selection delete the overlapped surface, as shown in the below pictures.

• As we can confirm deleting by clicking ok in the above window.
• Then the surface glitches have been removed from geometry as shown in the below picture.

• We have to use the same steps to remove the all overlapped surface in the entire geometry.
• After we have done with the overlapped surface, we are going to deal with single cons and going to rectify the errors.

• These much of single cons have to be rectified, we can use multiple tools to so.
• some of the tools are fill hole, new surface....

• first, we have to delete the extra surface which we don't need here.
• After deleting it we end up with an open loop of surface which we can use the fill hole tool to cover up as shown in the below picture.

• Moving to another con, here we have to create a new surface first then use the fill hole option.

• Similarly use the above steps to make the single cons get eradicated from the geometry.
• Generate the Hot points as shown in the below picture.

• Create new surfaces, such that it is sufficient enough to close the opening without any modification in the geometry.

• Moving to the triple cons, examine whether it is needed in the geometry or not and decided to keep it or not.

• As we can see in the above picture that this triple con is necessary for the geometry. So, we are going to keep it in the meshing part.
• By this step we are completed with the TOPO cleanup procedures, we can proceed with the meshing process.
• Close all the openings in the geometry to perform the volumetric meshing.

Boundary Flagging:

• Before the meshing process, we have to name the PIDs (boundary) individually, as shown in the picture.
• Create a new PSHELL for every single PID.

MESHING PROCEDURE:

Step 1: Provide the mesh length as given in the challenge in both perimeters and macros for each PIDs as mention below,

• Blade stage-1 = 1 mm
• Blade stage-2 = 1 mm
• Impeller = 2 mm
• Shaft rotor = 1 mm
• Turbo casing = 5 mm
• Compressor casing = 5 mm
• Inlet casing cover = 5 mm

Step 2: Give the mesh parameters such as,

* Mesh Length

* Type of Mesh

* Shape of Mesh - (Tria)

Step 3: Give the Quality of mesh in the Quality criteria tool tab.

Step 4: After given the required values, to deploy the mesh, use the mesh generation tool. Use spot mesh to generate mesh over the selected faces (PIDs).

• Change the required values as given and mesh all the surfaces.

Volumetric Mesh:

• Delete the unwanted volumes first.
• Then Remesh the volumes individually as using the given mesh lengths.

Conclusions:

• Hence, the topology cleanup and mesh generation (surface and volume) are done on the given turbocharger assembly using ANSA as per the given specifications.
• Tria and tetra mesh elements were used to generate the surface and volumetric mesh respectively.
• A total of 916752 tria (surface mesh) and 9893019 tetras (volumetric mesh) elements were generated.