Francis Turbine - Results not converging

Project Support
1

Hi there, I’m running a simulation of a francis turbine in order to get pressure inlet, efficiency and power output.

The project is located at https://www.simscale.com/workbench/?pid=167762004632123547&mi=spec%3Ac4fa38e6-6bc6-4f66-bd33-86d728e0d5f9%2Cservice%3ASIMULATION%2Cstrategy%3A2&ps=domain

I have created the flow volume and simulation according your francis turbine tutorial, and although it seems to be ok regarding to the geometry and rotating region, the inlet pressure and pressure moment z results are not converging.

Furthermore, I would ask you to please confirm that in my case I need to take only (pressure moment z * angular velocity) to output power calculation.

Thanks in advance,

Flavio Varani

2

Hi Flavio, I just checked your current run and it seems that there is no divergence issue any more, what did you change? :slight_smile:

3

Hi Fillia,

I have changed the geometry in order to make it round, smoth as possible, as well increased the inlet and outlet length.

Please take a look in the followings results of run 6, you will see that it is a bit better than before, but still not yet converging:

Average Area 1: p(Pa)
Forces and Moments 1: Pressure moment z

Thanks,
Flavio

4

It is not actually bad, 1e-3 is a good starting point, and it seems to be slowly converging, why don’t you continue your run for more iterations?

5

Hi, unfortunately didn’t work…

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image1275×495 26.2 KB

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image1289×443 14.5 KB

If you have any idea, please let me know

Flavio

6

Hi Flavio, quick question, in your previous studies, did you set the Cell zone for the MRF region before the mesh generation?

cell zone
cell zone429×723 32.7 KB

\Check the Standard mesher section here:

Let me know, and we can make changes according to your answer :slight_smile:
Best regards,
Fillia

7

Hi Fillia, in fact I didn’t do this.