Aerodynamic loads

Hello everyone,

I have 2 questions about aerodynamic loads calculated with FAST.

  • How are aerodynamic loads taken into account during linearization process?
  • Is the induced wind speed due to system movement taken into account ?

Thank you in advance.

With best regards,

Maxime PHILIPPE
Ph.D Candidate
Laboratoire de Mécanique des Fluides
Ecole Centrale Nantes
Nantes, France

Dear Maxime,

As you’ve probably discovered if you’ve tried to linearize a FAST with AeroDyn model, the code will not allow you to linearize a model with dynamic stall or dynamic inflow enabled. That is, you must set StallMod to STEADY and InfModel to EQUIL. So, the linearized model uses static airfoil data and employs the quasi-steady induction calculation (or no induction if IndModel = NONE) during linearization. In some cases, it is more accurate to assume a frozen wake during linearization–see, for example, the forum topic found here: http://forums.nrel.gov/t/gain-scheduling/286/1. We’ve implemented the frozen wake linearization option in a slightly customized version of FAST with AeroDyn. In the rewrite of AeroDyn that we are working on, we plan to add options at some point for linearization of dynamic stall and dynamic inflow.

In the time-domain solution of FAST with AeroDyn, certainly the induced wind speed calculation takes into account system movement. In the linearization process, this is also true given the limitations stated above.

I hope that helps.

Best regards,

Dear Jason,

Thank you for your answer. It confirms my understanding of aerodynamic calculation during the linearization.

With best regards,

Maxime PHILIPPE