Torque Prediction
Dear All,
I am simulating a flow over a ceiling fan in an enclosed room. the fan is rotating at speeds in the range of 300-400 RPM. I am defining a rotating domain around the fan and following the frozen rotor approach. The fan blade is only 1 mm thick. I have tried to predict the torque over the fan, the error varies from 15-60% from the actual value for various cases. However the mass flow variation is well within 2% of experiments. I recently approached ANSYS support for it and they suggested going for y plus value for first cell as 1 as I am using SST model. But because of that the error increased further by 10% in torque and to 20% in mass flow ( y did this happen ? ) Can anyone suggest how to improve my accuracy and consistency of such a simulation. |
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Have you read this FAQ? http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F
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Hi Glenn,
Yes I have read that a number of times. Still I couldnt find a solution to my problem. One additional thing, by reducing yplus to below 1, my solution is not converging properly, my residuals are stable ( although high ) but my torque changes with every iteration it has already been around 1400 iterations. How should I get a stable and accurate solution for my problem. |
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Hi ghorrocks,
My simulation is quite a low rpm and low blade loading simulation. It does not involve flow separation. |
Then you should be able to get an accurate result for this model.
Can you post some images and your CCL? Maybe the output file too. |
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I also have the same issue in terms of torque prediction. The CFM predictions are quite good. But the torque predictions are varying from 0 to 50%. Did you get any breakthrough?We are trying several methods and didnt get any success. Please reply to my email id: trilok99@gmail.com |
What you need to do for an accurate simulation is described in the link I posted in post #3.
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