Aerodynamic sensitivity gradients of the torque and thrust force

Wind & Water Rotor Aerodynamics
1

Dear community,

I am working on the control of the NREL 5-MW reference wind turbine with the OC4 Semi-submersible platform in above-rated wind speeds (Region 3). I need the aerodynamic torque and thrust force sensitivities in response to change in generator speed, wind speed, and blade pitch angle. Stockhouse et al. in the conference paper “Sink or Swim: A Tutorial on the Control of Floating Wind Turbines,” 2023 American Control Conference (ACC), shows the following figure but for another wind turbine. How can I have this data for the 5MW OC4 Semi-submersible FOWT?

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Thank you for your help.

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Dear @Michel.Owayjan,

I did not co-author this paper and cannot confirm how Stockhouse et al computed these graphs, but the linearization functionality of OpenFAST can compute these partial derivatives. By including the aerodynamic thrust (RtAeroFxh) and torque (RtAeroMxh) as outputs in AeroDyn, these aerodynamic derivatives can be found at different operating points through elements of the full-system C matrix (for the derivative with respect to generator speed state of ElastoDyn) and D matrix (for the derivative with respect to the wind speed and collective blade-pitch angle). If you don’t wish to have the complications of aerodynamic states, I would linearize with DBEMT_Mod = -1 (frozen wake) and UA_Mod = 0 in AeroDyn.

Best regards,

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