SimScale CAE Forum

Blower analysis does not start


#1

I have set up a model of a blower, which includes a rotation volume to model the impeller.
The model seems to be error free, but the simulation does not start. After few seconds an error message appear suggesting to check the “event log” and the “Solver log”, which however I cannot find.
Could you help me please?

[https://www.simscale.com/workbench/?pid=7157969807146104677&mi=run%3A6%2Csimulation%3A1&mt=SIMULATION_RUN ]


#2

Hi @mmargonari!

The boundary conditions you set are not working because you just define a pressure inlet and close the outlet with a no-slip condition. To see how a similar case like this can be set up please have a look at this project: Radial Fan Simulation.

Best,

Jousef


#3

Dear jousefm,

thank you for the reply. I have see the project you mention but I still cannot understand. I would like to simulate two specific conditions for the blower:

  • maximum flow rate (I suppose that this can be achieved imposing the same environmental pressure at inlet and outlet).
  • zero flow rate (imposing a wall condition at outlet and the environmental pressure at inlet).

For both these two scenarios I do not manage to run the simulation.
Is there something wrong in what I write above?

In the project you suggested to me a pressure is applied to the inlet and a sligly higher pressure to the outlet, but with this kind of conditions I cannot model the desired ones. Am I wrong?

Thank you

Best

MAx


#4

I have tried to change the boundary conditions at inlet and outlet but the problem is always the same. The analysis does not start at all.
I guess there is another issue but I cannot understand where…

Best

MAx


#5

Hi Max,

working with a pressure inlet and outlet can work if you set the total pressure to 0 at the inlet and use a fixed pressure (static) to zero at the outlet, hypothetically. Will give it a try and let you know about the outcome.

Best,

Jousef


#6

Update: Simulation not cooperative :smiley: I assume that this might be geometry related as the MRF zone is being cut but not 100% sure, let me give you a (more promising) update later on.

Best,

Jousef


#7

Thank you very much. My feeling is that i am doing something wrong, may be there is something in the geometry.
I have just modeled the fluid volume, together with an auxiliary cylinder to define the rotating portion of the model. No impeller has been addedncluded into the model. Is it right?

Best

Max


#8

Hi Max,

can you please try not to use the automatic internal meshing operation but the parametric one to create a CellZone?

That should work :slight_smile: If not ping me and I will jump back in.

Happy weekend!

Jousef


#9

Dear jousefm,

I have tried to switch to the parametric mesh, but without satisfaction. I actually get meshed just portions of the model, depending on the position of the material point.
Then, I have set up a new project:

https://www.simscale.com/workbench/?pid=5061084902163767457&mi=spec%3Ac493ac55-8381-4c9e-bbde-9d7818d7a71a%2Cservice%3AMESHING%2Cstrategy%3A8&sh=1

using only the lowest part of the blower and removing the rotating impeller, to simplify the model. Applied a flow rate at inlet and a pressure at outlet, but even in this case the analysis does not start…
I am confused because there is something that is wrong in the model (geometry, mesh,…??) but I cannot understand what exactly I am doing wrong.

Can you see the bug???

Thank you in advance

MAx


#10

Hi Max,

that’s because the propeller is not enclosed in a cylinder. You have to enclose it and the mesh will be successful assuming there are no other geometrical issues (which there are not as far as I can tell). Also this is a new geometry, you should have tried it with the old one to check. In the new one the enclosure is missing as you can see.

Best,

Jousef


#11

Dear jousefm,

please apologize me, but I still continue in not understanding. When I set up a model with rotating parts:

  • should I upload the geometry of the impeller? If so, has the fluid volume to exclude the impeller volume?
  • other possibility: upload just the fluid volume (impeller excluded)?

If I look at the model I see that the auxiliary volume (which is a cylinder) to define the rotating portion of the model include the impeller, so I think it should be right.

Thank you

Best

Max


#12

Hi Max,

maybe this tutorial here helps you: MRF Zone Tutorial. As mentioned you always upload the impeller enclosed in a cylinder and that can then be surrounded by another system like a pump or anything else - but use the parametric mesh. Could be that I missed a point from you here but the geometry you shared has no cylinder around the impeller to actually apply the MRF on so that does not work.

Let me know if anything else is unclear.

Cheers,

Jousef