CFD meshing on Turbocharger

 CFD meshing on Turbocharger

 Aim:

For the given model of a turbocharger, check for the geometrical errors to make appropriate volumes. Create and assign PIDs accordingly. Create surface mesh and use that to create a volumetric 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

Method:

First load the model in ansa

What is Turbocharger?

The turbocharger is to compress more air flowing into the engine's cylinder. When air is compressed the oxygen molecules are packed closer together. This increase in air means that more fuel can be added for the same size naturally aspirated engine.

Turbocharger Model:

 Now lets see different parts of this turbocharger

By checking the model in wireframe mode we can detect the red cons that is where is the errors.Before solving the red cons we have to delete the pink glitching surface that is overlapped.Most convenient way to delete the surface is to delete the PID that forms the surface.

Then we will go on solving the red cons .

 

We will  delete the face and create a new face there.

So we have to delete the inside surface that intersect the two surfaces.So select intersect then select the first plane and second plane then middle click and delete the intersected plane.

Now we have to straighten the curved portions on two opposite sides by selecting cut option.Then delete the two small surfaces and the respective big surface and create a new plane.

Now we have to create a surface on that red cons.

Now we are creating two new curves in between for the sake of convenience of creating new planes. First take the one transform option - red con -middle click-take respective hot points - middle click.Then create two planes on that surfaces.

Then by curves -Delete option delete the  transformed curves.

Now we have to fill the surface by coping the side surface by the following above options on image and select the entity. Before that create a hot point in between the two hot points to select semmetry three point method then ok then finish.

Then fill the hole between the surface by fill hole option and hit a Topo and select the unjoined red cons and it will make them double cons.

Then go to checks manager -Geometry_checks -Execute and see that no geometry error. Now we will remove the penetration errors.

Pnetration errors.

Now we have to delete the inside surfaces of the shaft to make the shaft one volume and delete the inside intersecting surfaces.

Hit a topo to make the red cons into yellow.

 

create a surfece by element selection on the vacant portion and then by loop selection.

Then delete the inside surfaces in the second blades planes . 

 

 

 After deleting all inside surface in second blade planes shaft we are going to solve the overlapped glitching surface at the second blade plane end.Hit a topo to join the red cons and make it yellow.

 

 

 now we have to delete the mixed glitching surface,to do this we will project the yellow con between brown and inside surface on pink surface by cons project ,then this two cons will also be on the pink shaft as well and form an another volume on the pink shaft so we can delete the volume of the pink shaft so as to remove the overlapped portion.

To do that tap on cons - project- tap the con - middle click - tap the pink shaft portions - middle click.

 

 Now delete the portion between the triple cons.

 

Now delete the inside surface of the triple cons.

Now go to check maneger - penetration error , only 3 errors left.Errors on the blade stage 1 and blade stage 2 removed.

 

This glitching surface is penetrating the turbine casing so we have to delete this by deleting the glitching and then delete the shaft portion as the shaft is penetrating the turbine casing , so we will project the cons on the shaft surface by cons project and delete that portion.

 

 

Now we will delete the mixed glitching surface and also delete the portion of the shaft in the same way by cons project as the shaft is penetrating the compressor casing so it will create a penetration error.

 

Now we have to delete the inside glitching surface and have to delete the surface as its creating an extra surface inside leading to penetration error.

When i am going to delete the surface its gonna delete the blades as well so we have to separate the surface by joining the hot points . To do this take the upper con on the shaft and project the con on the surface and then delete it.

Now again go to checks manager and execute then we have one penetration error - select it and show only and delete it.

Now we have removed all the errors. next we will do surface meshing . To do that we have to cover up all the opened surfaces.

 Surface meshing

 

 

like this.

We also have to cover up the four places above.

 

Now we will name all the pids so as for the convenience of surface meshing.

 

open pids double click on it and change the name.

Compressor_casing:

Impeller_casing:

Inlet_casing:

Turbo_casing:

Blade_stage_1:

 Blade_stage_2:

Shaft_casing:

First select the pid - right click - apply - box select the shaft portions then all the different portions of the shaft forming shaft pid will combine.

 

Now delete the unnecessary pids by compress.

First Blade_stage_1, Blade_stage_2, shaft as 1mm. So go to mesh - classic mesh - peremeters - spacing - auto cfd . For perimrter select the body and give max and min length as 1.5mm and .5mm and same for macros . Then go 

to mesh generation - CFD - visible.

(we will freeze each component after meshing by clicking on macros-freeze and select by left click.we are doing that as different components are connected to each other at different portion so as leading some components unmeshed or meshed improperly. After meshing all components we will unfreeze all by freeze/unfreeze and right select.)

For Impeller_casing 2mm , for compressor, turbo and inlet casing 5mm.

Volume_meshing:

First go to the right corner- drop down menu and v_mesh.Then click on define- then in the poop up ok - it will open detected volume. As we are doing internal meshing we will delete all the external volume.

 

 These volumes are detected.

 This is internal volume .

 

This is external volume so we have to delete this.

 

This is external volume so we have to delete this.

 

This is internal volume .

Then in each volume name in the menu bar on the undefined section click there and select tetra cfd and then right click on unmeshed portion and mesh.

 

Creating an internal plane:

 

Now to show the internal meshing we are taking a cut plane inside so go to cut palne - New - default xy plane , choose plane centre, double click on the name empty on appeared poop up and ok .

 

Conclusion:

1.Achieved volumetric mesh of the turbocharger model.

2.Volumetric mesh can be achieved only after creating surface mesh successfully, or else the geometry can give fatal errors while volume meshing.

3.Overlapped surface can be deleted using the universal delete option.

4.Unecessary single and triple cons can be removed and editted using different tools such as cons project, topo, release and fine tools while goemetry clean up.

5.Successfull volumetric mesh can be achieved only after correct geometric clean up and surface mesh.

 

 

 

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