Week 3 Challenge : CFD meshing on Turbocharger

PROJECT REPORT

Aim:

Make Volumetric mesh in given geometry of turbo charger, first clean the geometry clear all the flaws in geometry and then make surface mesh so we can proceed with volumetric mesh and at last selecting the required volume and creating volumetric mesh in those volumes

Given Geometry:

First upload the geometry in ANSA and set them in PDI mode, as we can see the gemotry has many flaws so we need to correct all on them. The major ones we are looking for are as follow

• Overlap faces
• Single cons
• Triple cons
• Duplicate surface or missing surfaces

Given Geometry

As we can see the pink colour PID is overlapping so we can see the glitch, So first we will hide the green PDI with NOT option and then we can easily delete the pink colour PDI

Now we can select the pink PDI easily and delete it like this we need to use appropriate option to remuve the flaws from geometry correctly

This are the single cons we need to fix so let’s fix them one by one

• The front red con we need to delete one face and create a new one as shown below

• For second problem the face we need to make must be in some separate parts as shown

For that we need to use multi project for projecting the hot points and creating surfaces one by one

Like this we need to faces one by one and complete the entire hole

• At the bottom we cannot make the phases entire at one time as the ANSA doesn’t predict the correct faces so we need to divide this one as well

Creating hot points to divide the surfaces

Creating new faces on them one by one

• In this case we need to use intersection tool as the two faces are intersecting each another

Intersection option will itself show the option to delete the exceeding surface

Also, there are further clean-ups to make the geometry ready for meshing for many overlaps surfaces and unwanted surfaces, like in shaft of rotor we need to make the entire shaft in single volume it will help us in volumetric mesh so we need to delete all the surfaces in the between.

Now we need to check overlap surfaces under all the surfaces we may find some in rotor shaft which we need to cut the shaft in some places by using project cons option and delete option

Now, we need to close the geometry and make faces on each inlet and outlet as shown below also close body is important for volumetric mesh as it can detect the volume. In all this process there we can create many single cons which we need to keep on clearing with the help of TOPO option

Now we can name the PIDs as required

After that we can start with surface meshing

MESHING:

Now, our surface mesh sizes are as follow

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

Now in ANSA we usual put the target length in 3 locations Mesh parameter, Quality criteria and length in which we select macros and parameter

In this geometry there will be many macros where the edge will be shared by two type of target length in such cases, we need to keep the target length in macros and parameters in length option fluting between the two separate target lengths.

We start one PID at time

As shown in fig the mesh of the outer casing must range from 1-5 so it can accommodate the same

After meshing all the components as per the target length, we must check that there are no unmeshed surfaces if there are any, we cannot do volumetric mesh.

VOLUMETRIC MESHING:

Volumetric meshing can only be done after 2D meshing, now to check which volumes are capable of getting a mesh we can use DEFINE from volume and the whole-body option then Ansa will show all the volumes present in body

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

PDI which represent the volume of area in which fluid is going to be present we can mesh that area

After checking every thing our volume which is to mesh will look like this

Now, to do volumetric mesh it is easy we just need to select the PID from list and do right click and select Re- Mesh after that it will ask for type as we need the mesh for CFD purpose we can choose tetra CFD and click ok then the volume will start meshing and as the element size increases the software starts to work slowly

For bigger volumes it may take some time

CROSS SECTION AFTER MESHING

CONCLUSION:

• Learned about more complex tools to clear the geometry and making the geometry suitable for meshing
• Created volumetric mesh