Removing moordyn in IEA15MW UMAINE Semi case

Hello all,

Recently, I did a small test by desabling the moordyn and setting WaveMod=0, CurrMod=0 and PotMod=0 (still water) in IEAWindTask37/IEA15MW UMAINE Semi case, without changing other options. Wind blows from west to east, and I expected to see the turbine would float away along x direction, but instead, the turbine deviates slightly to y+ direction as shown in the following animation

I run also an onshore case with IEA15MW, the force on the tower top is shown in the figure, I saw a non-zero mean side-to-side shear force on tower top (~27kN for this case)

I would like to know does it make sense and how to avoid this load on the side-to-side direction?
Best regards

Dear @Wenchao.Yu,

Your results make sense to me. In addition to the rotor thrust, the aerodynamic loads will generate a torque that will deflect the tower in the side-side direction, which means that thrust will induce a yaw moment as well. Yaw moments will also be generated through rotor gyroscopics. Side-side forces will also be induced in the process.

You could eliminate the transfer of rotor torque to the support structure by disabling the torque controller, but that would lead to a rotor speed up and likely other problems like blade instabilities.

Best regards,

Dear @Jason.Jonkman,

Thanks a lot for the clarification!

Just for your information:

For the same onshore case mentioned previously,
If just disable the torque controller:

If disable both torque and pitch control:

Best regards,