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

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Old   October 26, 2022, 14:58
Default Calculating Power in Steady-state vs Transient for vertical wind turbine
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Ahmed Elsayed
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I'm trying to calculate the power for vertical wind turbine at specific rpm.


should I use steady states simulation or transient?
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Old   October 26, 2022, 17:01
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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.
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Old   October 26, 2022, 17:59
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Quote:
Originally Posted by bolbol View Post
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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Old   October 26, 2022, 22:13
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Quote:
Originally Posted by Opaque View Post
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
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Old   October 27, 2022, 01:11
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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.
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Old   October 27, 2022, 08:21
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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.
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