Week 3 Challenge : CFD meshing on Turbocharger

Aim: Check the geometrical errors to make appropriate volumes and assign the PID's. Also perform the surface mesh on Turbocharger.

Software used: ANSA Pre-processor

Theory:

A turbocharger is a device fitted to a vehicle’s engine that is designed to improve the overall efficiency and increase performance. This is the reason why many auto manufacturers are choosing to turbocharge their vehicles.

How does it work:

A turbo is made up of two halves joined together by a shaft. On one side, hot exhaust gasses spin the turbine that is connected to another turbine which sucks air in and compresses it into the engine. This compression is what gives the engine the extra power and efficiency because as more air can go in the combustion chamber, more fuel can be added for more power.

Figure 1 is working of Turbo Charger

Cad Model:

Figure 2 CAD Model

Geometry cleanup:

First we have to clean the unwanted surface available in the geometry using PID region.

Using universal delete option selected the unwanted PID region click the middle scroll button

Figure 3 overlap surfaces

Next remove the single cons (red in colour) and create the new surface using coons.

Select ENT for single surface selection, use delete option for remove the surface.

Make a new surface using new in faces, select coons and loop selection for creating new surface.

Figure 4

Figure 5

Intersect:

Next some of the surface is interaction with other surface, we have to remove the interact surface using interact option in faces.

Faces - Intersect - select first face - middle click - select second face - middle click

Figure 6 intersect portion

Release option:

Suppose we deleted UN wanted surface available in the CAD File, the con is not updated, it shows triple con.

For updating the con using releases option in faces.

Cons - release - select the triple con - click middle button - remove unwanted hot points - click topo on that surface.

Figure 7 remove excess hot points

Parametric option:

If we have smooth rounded surfaces, for creating a new surface use parametric.

Parametric creates multi hot points, use that hot points to create a surface with the help of coons.

Figure 8 how to use parametric option

Figure 9

Geometry Checks:

Go to geometry checks for any error is available in the geometry.

Goto script - checks -geometry -execute.

We have to reduce all the errors as shown in the above figure.

Remove Single cons:

First we are checking the single cons are present or not.

Figure 10 removing single cons

Remove Triple cons:

Deleting extra surfaces, that will converted into double cons.

Figure 11 checking triple cons

Project-cons and Auxiliaries-fine:

Here overlapped surface is available in the cad geometry, if we try to delete overlapped surface it will delete the entire surface.

we used cons - projects for created a projected cons in a particular overlapped area that will help to delete that particular projected area.

Auxiliaries - fine is used for modified irregular cons in the overlapped area as shown in the below figure12 and 13.

Figure 12 checking overlapped surfaces in blades 2

Figure 13

Figure 14

Close opening's for the Volumetric Mesh:

Faces - new -cons -select coons -middle click -surface created

Figure 15 close openings for vol mesh

Figure 16

Figure 17

We clean the all the erros in the geometry like clean the single the single cons and triple cons.

Assign PID's:

Blades and Shaft:

Figure 18 blades and Shaft

Compressor casing:

Figure 19 compressor casing

Turbo Casing:

Figure 20 Turbo casing

Meshing:

Surface Meshing:

For this problem we are prforming the different target lengths for different PID's as shown in the below.

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

Turbo Casing:

Target length = 5 mm

Element type = Tria

Meshing Parameters:

Quality Criteria:

Mesh - Parameters - perimeter - length =5mm - Mesh generation - spot mesh - visible.

Compressor Casing:

Target length = 5 mm

Element type = Tria

Figure 21 compressor casing meshing

Turbo casing & Inlet cover:

Figure 22 Turbo casing and inlet cover meshing

Impeller:

Target length = 2 mm

Element type = Tria

Mesh Parameters:

Quality Criteria:

Figure 23 Impeller meshing

Blades and Shaft rotor:

Target length = 1 mm

Element type = Tria

Blades Mesh

Figure 24 Blades mesh

Shaft Mesh:

Figure 25 Shaft mesh

Unmeshed surface are formed due to different surface length mesh.

Figure 26 unmeshed surface's

Re construct the mesh in surface using Macro's:

Macro's - cut - in options list - select mesh reconstruct - select options as parametric - create own surface - do mesh in particular surface.

Figure 27 before and after changes the target length in cut surface

Volumetric Mesh:

In structured mesh if it is not showing any unmeshed points then go for volumetric mesh.

Long press on Define, it will pop up one window. Select whole db it will create available volume's in the cad model.

Next remove the unwanted volume (like thickness).

Figure 28 volumetric region

Tetra hydra elements:

Figure 29 cut view of Tetrahydra elements

Conclusions:

Surface mesh and volumetric mesh done for given Turbocharger model.

Also cleaned the geometry and topological errors in the given geometry model.