Week 3 Challenge : CFD meshing on Turbocharger

AIM: To check for the geometrical errors then create and assign PIDs. 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.

TOOLS USED:

Classic TOPO:

1. Checks: It is used to check the errors in the model.

• Geometry: It is useful to find errors in the geometry

2. Hot Points:

• project: It projects the points in the selected cons or faces.
• Parametrical: It insert hot points parametrically along the length of selected CONS Or Curve.

3. CONS:

• Fill hole: It fills the holes and openings.
• Release: It releases the topology of selected CONS.
• Project: It projects the curves or cons on faces and cut them.

4. Faces:

• New: It is useful to create a new face anywhere in the geometry.
• Delete: If any unwanted part is created it will remove it.
• TOPO: It merges the CONS.
• Intersect: Intersects the two different faces.

5. ENT: It can select any entity one by one.
6. PID: It can select one by one or with the box selection.
7. Not: It disappears the visible entities.
8. All: Bring back all the entities to the current window.
9. Compress: It compress the unused entities.
10. Auxiliaries:

• Fine: It increase or decrease the resolution of selected CONS or curves.

Classic Mesh:

1. Perimeters:

• Length: It is defined to mention the distance of the nodes.

2. Macros:

• Cut: Cut a macro area with two perimeter nodes or hot points.

2. Mesh Generation:

• Spot mesh: It is the tool to mesh the geometry by nodes on the surface.

3. Mesh parameters: For improvement of mesh generation.
4. Quality criteria: For the quality presentation of the geometry.
5. PIDs: Property list for specifications of properties and boundary condition.

Volumetric Mesh:

1. Volumes:

• Define: Definition of volume entites.

PROCEDURE:

1. Open the model in the ANSA.
2. To make the model visible with the faces use the ‘shadow tool’ present in the bottom of the window.
3. First go for the “checks>geometry” and check how many and where are the errors and then execute.
4. To create a new face there are different methods to use one of them is by using the tool “topo>faces>new>existing surface.”
5. For checking the overlapped surface, you can use “Faces>TOPO.”
6. Delete the overlapped surface by using universal delete option by selecting the surface which you want to delete.
7. If any extended surface is located first intersect by using “faces> intersect” tool and delete the surface once it forms a con.
8. If you use release tool “Cons>Release” it will separate triple con into three different single cons.
9. If you do ‘TOPO’ from ‘faces’ it will do the opposite of the release, it will merge the cons to form a double con.
10. If you don’t want a face or a line in the model, you can remove it by using “TOPO>Faces>Delete.”
11. After the topology cleanup assign the PIDs for every component {as shown fig (1)} by using PIDs properties. And by using tools from feature selection: ENT & PIDs>PID/PID region.
12. After completion of Topology cleanup let us move to the mesh generation.
13. Whenever you start with the mesh first step should be giving its length by using “Classic Mesh>perimeters>length.”
14. In the length option set the Perimeters and Macros length as per the requirements given in the aim.
15. After mentioning the length, give the target length and element type as ‘tria’ in the Mesh parameters and check the quality criteria and change the min and max length.
16. After giving the lengths mesh the components individually with the defined lengths.
17. Every component has different criteria, so it is changed accordingly.
18. After giving the parameters deploy the Mesh by using tool “Mesh generation>Spot mesh.”
19. After meshing you will find some meshed area is erased. Its because with two target lengths from two different faces meeting on the same line makes them erased.
20. For that you can choose only CONS in the perimeters of a face and leave the Macros as it is, so that Macros does not change the lengths upon meeting and does not erase.
21. After meshing the erased surface, you can observe the common point of the two different faces with different target lengths are merging with each other.
22. But it is disturbing the mesh of small target lengths, so in order to correct that, you can use the tool (“Macros>cut”) it will cut into the faces and create the new face for the disturbing surface.
23. After the surface mesh proceed to volumetric mesh.
24. Volumetric mesh is a kind of 3D element mesh.
25. After entering the V.Mesh your first task is to define the model by using (“V.Mesh>Volume>Define.”)
26. In that you can choose it as a visible model or whole database as per your requirements.
27. Choose the whole database and click ‘ok’.
28. It will show you the volume list, by default it will detect the volumes.
29. Volumes are nothing but ANSAs closed geometry, which is closed in the TOPO mode.
30. Few volumes are useful and other you can delete if not necessary.
31. We will be only meshing the volume that occupied by parent geometry thickness.
32. Define the volumes for each component which are present.
33. Mesh it as ‘Tetra CFD’ mesh (as shown in fig{3}).
34. And then by hiding some tetra elements you can check the cross section it is done correctly or not (as shown in fig), those are basically tetra elements.
35. Finally V.Mesh also done successfully (as shown in fig{4}).

FIG 1. Assigning of PIDs.

FIG 2. Classic Mesh.

FIG 3. Meshed with V.Mesh.

FIG 4. Cross section of Tetra Elements.

RESULT: 

• The main model is cleaned up and fully refined
• The mesh was fine and cross section was also very good.

CONCLUSION:

The given model has been meshed with the given target lengths and element type and successfully meshed with volumetric mesh.