yaw correction

[sffgd]

Hi everyone，

The wind turbine is in idle shutdown, I set NacYaw=YawNeut=10° to ensure the neutral yaw position is constant and keep YawDOF=True, but when I set the wind speed to 45m/s, I get a PtfmYaw maximum of 9°, which looks like a lot of yaw motion, I wonder if the openfast model includes the ‘yaw correction’?

Best regard，

[jjonkman]

Dear @sffgd,

I'm not sure what you mean by "yaw correction"? In idling conditions, I suspect you've disable most aerodynamic modeling options in AeroDyn, leaving just table look-up airfoil loads from the blade-element solution; is that correct?

Are you using an example OpenFAST model provided by NREL or is this your own model?

Is the yaw deflection of 1-deg commensurate with the yaw moment and YawSpr you are using in ServoDyn?

Best regards,

[sffgd]

Dear @jjonkman，

I made sure I didn't change the YawSpr values in ServoDyn and kept the defaults, the wind turbine shutdown idle rotor settings are as follows:

AeroDyn：
WakeMod=0, AFAeroMod=1, TwrAero=Ture

ServoDyn:
GenTiStr=Ture, TimGenon>Tmax
PCMode=0, VSControl=0, GenModel=1

ElastoDyn
GenDoF=True, Rotspeed=0, BIPitch(1,2,3)=90°

Note that in HydroDyn I set WaveDirRange=0 in order to make the waves shoot in a certain direction, I'm not sure if this is a reasonable setting?

The following documents are attached
[IEA-15-240-RWT-UMaineSemi_AeroDyn15.docx](https://github.com/user-attachments/files/18163997/IEA-15-240-RWT-

[jjonkman]

Dear @sffgd,

Your link does not seem to work for me, but it sounds like you are using the IEA Wind 15-MW RWT.

Can you answer my last question:

Is the yaw deflection of 1-deg commensurate with the yaw moment and YawSpr you are using in ServoDyn?.

That is, does YawMom / YawSpr = 1 degree?

Best regards,

[sffgd]

Dear @jjonkman，

Yes, I use the IEA Wind 15-MW RWT.

YawMom/YawSpr not equal to 1 degree.
The explanation is as follows: Maximum value of YawBrMzp=Maximum value of YawMon=57710 KN-m, and YawSpr=8458453511 N-m/rad=147627.86 KN-m/d for 15MW wind turbine.

Best regards,

[jjonkman]

Dear @sffgd,

I'm not following your math. With YawMom = 57710 kNm = 57710000 Nm and YawSpr = 8458453511 Nm/rad, YawMom/YawSpr = 0.0068 rad = 0.39 deg, so, it is as at least close to what you are seeing.

Best regards,