Calculating Power in Steady-state vs Transient for vertical wind turbine

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 October 26, 2022, 14:58 Calculating Power in Steady-state vs Transient for vertical wind turbine #1 New Member   Ahmed Elsayed Join Date: Sep 2017 Posts: 28 Rep Power: 8 I'm trying to calculate the power for vertical wind turbine at specific rpm. should I use steady states simulation or transient?

 October 26, 2022, 17:01 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,696 Rep Power: 143 If steady state is representative of the actual situation then steady state is OK to use. If not you will have to use a full transient simulation. bolbol likes this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

October 26, 2022, 17:59
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Quote:
 Originally Posted by bolbol I'm trying to calculate the power for vertical wind turbine at specific rpm. should I use steady states simulation or transient?
You have to be more specific.

Do you want to know:
- the power produced at a specific constant RPM?
- or power as the turbine de/accelerates from one state to another?

Those are different simulation requirements and I would expect different results as well.

For the stationary state, I would go with Glenn's suggestion and use a steady-state model.

For the transient, you need to know how RPM changes in time as well and the model is more complex. Leave it with you to think about the additional complexities.
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October 26, 2022, 22:13
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Ahmed Elsayed
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Quote:
 Originally Posted by Opaque You have to be more specific. Do you want to know: - the power produced at a specific constant RPM? - or power as the turbine de/accelerates from one state to another? Those are different simulation requirements and I would expect different results as well. For the stationary state, I would go with Glenn's suggestion and use a steady-state model. For the transient, you need to know how RPM changes in time as well and the model is more complex. Leave it with you to think about the additional complexities.
I'm looking for the power at constant RPM / wind speed
So, I guess according to both replies. it's steady state

Thanks

 October 27, 2022, 01:11 #5 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,696 Rep Power: 143 No, that is not what we said. Even if you think the situation is steady state the flow might have transient flow features which are important. That is why you need to look at the flow and determine if there are significant transient features. Only then can you decide whether a steady state calculation is appropriate. Note I was not recommending you use a steady state simulation at all. I was recommending you look at your simulation and determine whether it is steady state. Only you can do this, as only you have the simulation results. bolbol likes this. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.

 October 27, 2022, 08:21 #6 Senior Member   Join Date: Jun 2009 Posts: 1,800 Rep Power: 32 Also, be careful what you intend to do with the results. You may get reasonable results for power with a given approximation (steady or transient), but those results may not be good enough to use for structural predictions. For example, you want to compute the forced response of the blades to the wind conditions. My point is that different approaches are required for different requirements. __________________ Note: I do not answer CFD questions by PM. CFD questions should be posted on the forum.