Week 3 Challenge : CFD meshing on Turbocharger

AIM: -

CFD Meshing on Turbocharger.

->ANSA- >Automatic net generation for structural analysis) is a computer-aided engineering tool for Finite Element Analysis and CFD Analysis widely used in the automotive industry. It is developed by BETA CAE Systems [Source: - Wikipedia]

->It is used for pre-processing task and it includes proper cleanup like a geometric clean up.

-> 2D & 3D it is very widely used in CA applications.

->ANSA maintains the association between CAD geometry and the FE mesh.

Objective: -

For the given model, check for the geometrical errors to make appropriate volumes. Create and assign PIDs as shown in the video. 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

Procedure: -

Step 1: - Importing the CAD Model

Go to the file - > open the file - > Search the location, where the CAD model is present- >Supposed another model is open in workspace then it will be discarded or saved - >Certain path where we had download or save the model, It can be identified by ‘’Turbocharger ANSA’’ - >Select it & click on enter.

Step 2: - Geometry clean

Geometry checks _> Can we found above the workplace in the line of Script tool _> Checks _ > Geometry _ > Template _ > ANSA checks mode is on/off, click on it to ON

Click on To checks to reach at the start of geometry checks _ > Geometry should be visible and active _ > Select the types of checks i.e. single cons, double cons, overlap faces, triple faces and etc _ > Execute _ > Errors showed it should be solved.

If we want to see the errors in the model like a preview then select the random errors in the geometry check and to select the whole model, we must drag down the cursor and select the model, later we had to click the mouse centre button then it will be shown in a current model where that exactly error is present with a white border.

To see the single cons error, we had to deselect the double cons and triple cons along with the shadow tool so that we can only see the single cons error

Objective of Geometry is to check the NO of errors present in the model.

Step 3: - Delete the Glitch i.e., overlap surface

Since in ANSA, if we see the glitch i.e., overlap surface which can we seen in pink colour in model and it can only be visible if the PID is selected as shown below in picture.

Before doing any kind of operation we had to delete the overlap surface, it can be done by deleting the overlap surface all over the model by selecting a part/ surface/ portion OR we can do by selecting the DELETE - > Select PID region - > Click the Pink Colour edges to deleted maximum overlap surface.

To check Whether the overlap is present in the model, by selecting the NOT Tool - > Select the PID region - > Click the green surface so that it will hide that surface, If the overlap is detect in this process it will be shown but in our case no overlap is found so the preview is seen in this manner as shown below,

Step 4: - Errors should be solved

Since the single cons error can be solved by using new faces

Click on Classic TOPO tool _ > Faces _ > New _ > Surface type _ > Select the surface as per your model requirement _ > Select the Cons border through Cursor _ > Click the mouse centre button.

Sometimes we can’t apply this method so we would be dividing into 2-3 steps my using hot points with the help of multi project as shown below,

Once we had done with this method we can go with the coons, surface existing, Fitted, Planar tool. For these we are going with the coons tool only where we had created the cons so that it will cover that surface itself and later we can use the loop method for whole surface.

In above picture we had use parameters tools to create a hot points in uniform distance, so that afterwards we can create a proper surface.

As we can see in the above image the shaft and the blade are overlap, so we had to delete that surface my using TOPO - > CONS - > PROJECT, Select the whole circumference which is shown in blue colour i.e. triple cons later select the surface and click centre button after doing this process if the surface occurs irregular than use the tool fine which is present under the Auxiliaries, purpose if using fine tools is for smooth surface. Once it done try to isolate all the regions except the shaft i.e. in pink colour so that we will delete that overlap surface after doing this step it will be seen as shown below,

Similarly, we will be doing for impeller i.e., in blue colour. while deleting the face of the impeller we will face some errors that is while deleting the face the other blade portion also gets deleted. To avoid this, we will be using cut tool which is present under the face tool option. So we will be using cut tool at the edge of the corners so that it will create a proper face so we can delete that face portion after doing this step we could observe the single cons, So changing the single cons into double cons with the help of TOPO tool which is present under the face tool option.

After doing this all, we will check the geometric error because before using meshing tool we had to fill/ cover the open surface.As we can see that the triple cons is present in turbocharger model, since these triple cons is accepted because it is connected it more than two surfaces.

Steps for PID assign…. Properties _ > Click _ > New pop-up box, It will shows the Pshell contain or PID

How to create a new PID?

To create a new PID_ > Right click _ > New _ > Pshell _ > new box will come up _ > Name (e.g.:- Outlet) _ > OK _> Properties new PID present _ > we can also change the colour by clicking twice on this □

To assign PID _ > Click on the PID, which has to apply on our model _ > Right click _ > Apply _ > Go to the model _ > Take the cursor to the Cross edge / face and click centre button.

How to delete extra PID _ > Select the PID _ > Go to the compress tool which is present in upper row, as shown below.

Assign PID as shown below,

Step 4:- Meshing

• Now going for the mesh option here we are considering the following terms,

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

• Element type = Tria

Select Classic MESH tool - > In that we had to go in perimeters after then click on Length.

- > choose the perimeters and to select the whole model we have to drag down the cursor and select the whole model, later we had to click the mouse centre button - > In length we have to give the number 5 as shown below in the picture

> Since after doing this for perimeters we are going to do exactly similar for macros.

Since we are moving for a mesh parameters and Quality criteria.

Select Mesh parameter - > In basic we had to choose the element type has TRIA and in mesh size the target length should be 5 as per these turbo casing.

Quality criteria _ > Tick all the parameters as shown in below picture _ > Minimum Criteria should be 3mm and maximum Criteria should be 7mm _ > Click on Apply.

• Now using Visible to provide the meshing in all parts of the turbo charger

For Visible _ > Mesh generation _ > spot mesh _ > Visible

Meshed Element with the target size of 5mm

The total no of elements under 5 mm is 114592.

Similarly we will be doing for Compressor casing, Inlet casing

The total no of elements under 5 mm is 42664.

The total no of elements under 5 mm is 7024.

Since we will be doing same for Blade stage-1, Blade stage-2, Shaft rotor, Impeller & only the elements parameters going to be change respectively

The total no of elements under 1 mm is 266040.

The total no of elements under 1 mm is 383550.

The total no of elements under 2 mm is 669497.

The total no of elements under 1 mm is 78531.

Since we can see in below picture, that some parts of turbo casing & Compressor casing is unmeshed because when two surface meets with a different mesh length then it creates the unmeshed surface.

So in that case we had to only apply spot mesh with a assigned terms and no need to use perimeters and macro, Only the assigned terms should me input in Quality criteria & Mesh parameters.

The total meshed elements is 920106.

Note:- for De-selecting use right click of mouse.

Step 5: - Volumetric Mesh

Before using V-mesh, we had to mesh the whole model.

V-mesh _ > Volume _ > Defence _ > Ask whole DB[data base] or visible , Go for whole DB _ > Click OK _ > Volume list appears or volume list can be select under the volumes

We need to check which volume is actually the volume in which fluid is going to be present and which other is only a thickness of our solid body.

In above picture we can see that the type & status are pending that’s means undefined and unmeshed. To mesh this we will select the one PID & click right key of mouse some parameters will occur in that we have to select the mesh tool and proceed after that the result will occurs it’s shows below, The important points to remember is that the type should be in TETRA CFD .

At the time of this process it took time near about 15-20 minutes on that moment the software will run slowly on mean time we had to save file.

Learning outcomes: -

• Volumetric mesh
• Topo tools
• 2D Meshing

https://drive.google.com/drive/folders/1bDFOQ7wmq5FNbBOSdfu4PZED9G48700Z?usp=share_link