Yaw bearing moment

Hello,

Is “YawBrMxp” transferred to the tower and thus cause tower side-side oscillations?
My understanding is that only friction torque that resists shaft rotation will be transferred to the tower. Please clarify. Thanks.

Regards,
Kumara

Dear @KumaraRaja.Eedara,

Yes, ElastoDyn output YawBrMxp represents the side-to-side bending moment transferred to the tower. The dominant component of YawBrMxp is the generator torque in most cases, but gearbox friction and side-to-side forces from the rotor also contribute.

Best regards,

Dear @Jason.Jonkman

Thanks for your response. Could you please confirm the below. In the shaft tilt = 0 case, the contribution of the rotor side-to-side forces to the “YawBrMxp” is because of the moment arm “Twr2Shft” (the distance between the ‘main shaft’ and ‘yaw bearing location’ along tower axis). Right?

Regards,
Kumara

Dear @KumaraRaja.Eedara,

That would be true if the applied side-to-side force was centered along the shaft axis. But such a force need not be centered along the shaft, e.g., in the presence of wind shear.

Best regards,