Week 3 Challenge : CFD meshing on Turbocharger

OBJECTIVES

To perform geometry cleanup, create PID for the various components of the Turbocharger and then conduct a surface mesh and volumetric mesh of the Turbocharger using the following target length:

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

Sequence of process

1. Start ANSA using the CFD Layout and the -performance_mode 3 argument.
2. 
3. Create a new file work environment
4. 
5. Import Turbocharger file from location in your computer using file menu
6. Ensure the geometry is in TOPO module
7. Check for geometry inaccuracies by switching between Entity and PID modes.
8. In the PID mode, it is observed that faces are overlapping
9. Navigate to the List menu bar in the ribbon and click on P to see list of assigned PIDS
10. Although, all the PIDs have same name, the color property can be used to identify each part
11. As faces are overlapping, the glitches have to be rectified.
12. By switching on and off the PIDs, it is observed that the overlapping pink face is not required
13. To resolve it, either the pink PID is deleted or switched off.
14. 
15. 
16. Next, use the checks tool in the ribbon to check for geometry errors
17. 
18. 
19. 
20. Resolve the single CONS errors in the compressor outlet by deleting the unwanted face
21. Create a face to finally resolve the single CONS error on the compressor outlet
22. 
23. 
24. Using the wireframe mode, there are further single CONS in the Blade stage 2
25. Using the intersect option, delete unwanted faces
26. 
27. Upon review, it appears the near the Blade stage 2, there are unwanted curved surfaces
28. Create a cut, delete unwanted faces and create a new face to fix the geometry
29. Using the wireframe mode, there are single CONS found in the Blade stage 1
30. Using the transform option in the curves module function, create curve between points
31. Using the new face in the face module function, create a face as shown below
32. Delete the curves created after successfully removing the CONS error
33. 
34. Using the wireframe mode, single CONS were found in the Turbine section
35. Insert a hot point at a point on the single CON
36. Navigate to the Transform menu in the Utilities menu bar and select COPY
37. Next select the entities, accept.
38. And in the dialog box, select symmetry and then mirror three points plane from the drop down menu
39. Select the hot points and accept
40. 
41. Using the fill hole, create a face on the hole
42. 
43. Do TOPO to connect the face
44. Perform error checks again on geometry to see that single CONS errors are resolved
45. Then perform checks on intersections errors.
46. This time, there were some intersections errors on the blades
47. Using the Not Boolean operation, isolate the compressor casing.
48. Next, lock it and perform TOPO. This operation reveals presence of Triple CONS
49. Using Not Boolean operations, remove the blades and delete the extra faces
50. Remove the middle section of shaft and delete the overlapping faces
51. 
52. 
53. Perform final check geometry and intersection errors
54. Next save the cleansed geometry in preparation for surface and volumetric mesh.
55. Then rename the assigned PIDs
56. Perform surface meshing. However, we need to create new surfaces at the bottom of the Turbine casing, inlet casing cover Compressor inlet and outlet to define volume
57. Navigate to the Mesh module and select classic mesh module
58. Conduct surface meshing for the blades and shaft rotor since they have the same target length of 1mm
59. Using Auto CFD function in the perimeter module with a 1mm target length
60. Define a spacing parameter of 0.5mm minimum and 1.5mm maximum since target length is 1mm
61. Using the perimeter and macros options, a mesh is obtained with a total element of 328872
62. 
63. Next conduct surface mesh for impeller using 2mm target length with a spacing of 1mm – 3mm
64. A total of 10019 elements mesh were generated for impeller meshing.
65. 
66. Conduct surface meshing for the Turbine casing, Compressor casing and inlet casing cover since they have the same target length of 5mm
67. Using 5mm target length with a spacing of 4mm – 5.5mm
68. A total of 144638 elements were generated.
69. 
70. However, when meshing was done for the entire geometry, there were 6 unmeshed surfaces
71. 
72. Next conduct the above meshing with the freeze option
73. 
74. 
75. 
76. Next unfreeze and conduct volumetric meshing
77. 
78. Navigate to the volume mesh module and use the define module function
79. 
80. 
81. 
82. Delete all external volumes
83. Conduct the mesh using Tetra CFD
84. 

Result Comparison

A total element of 328872 elements were generated for the blades and shaft

A total element of 10019 elements were generated for the impeller

A total of 144638 elements were generated for the Turbine, Compressor and inlet casing covers

The volume mesh generated 2531383 elements