Airfoil control in ServoDyn and AeroDyn

[theot-student]

Hello everyone,

I am currently using OpenFast to make simulation of OC3 wind turbine with controls. In the control file of ServoDyn I saw that an airfoil control exist. I have two question about it:

1. What is this control exactly doing? Is there any document that talk about this control and the implementation in OpenFast?
2. How can it be used in OpenFast? I tried to activate it in the ServoDyn input file and I have also change the interpolation method of the airfoil tables in AeroDyn input file to use the UserProp which I think is the control variable in AeroDyn (AFTabMod=3). When I run the simulation I got a value of the control in output of ServoDyn but there is no change in the simulation.

For information, I am using the ROSCO controller so it already have a controller for this airfoil implemented.

Thank you in advance for your help
T. Barbier

[jjonkman]

Dear @theot-student,

I don't see good documentation on the aerodynamic flow control options of ServoDyn and AeroDyn in the documentation. Here is a quick summary to enable aerodynamic flow control:

• In the AeroDyn primary input file, you must set AFTabMod = 3 to interpolate airfoil data in 2D based on AoA and UserProp.
• In the AeroDyn airfoil input file for the airfoils you want to control, you must have mulitiple airfoil tables (NumTabs > 1), each with different UserProp values. UserProp is a user-defined value that gets set through ServoDyn and can be used, e.g., to represent different trailing-edge flap or other flow control settings.
• In the ServoDyn input file, you must enable aerodynamic flow control by setting AfCmode > 1. Which AfCmode you have selected will determine how UserProp gets set, i.e., through a simple cosine function (AfCmode = 1, based on the subsequent inputs in the file), active control through Simulink/MATLAB (AfCmode = 4), active control through a DISCON DLL (AfCmode = 5).
• When AfCmode = 5, you must define aerodynamic flow control logic in the DISCON controller.

Best regards,