Negative Tower Fore-aft deformation at Cut-in wind speed

Hello everyone,
I am studying the response of the 15MW model under different loading conditions. The steady-state tower fore-aft deformation at the cut-in wind speed (3 m/s) has a value of -0.38m.
I could not understand why this value is negative. If someone could explain the mechanics behind this, it would be really helpful.


Dear Shubham,

My guess is at this low wind speed, the moment from the overhanging weight of the rotor-nacelle assembly, which causes the tower to deflect upwind, is larger than the moment caused by the rotor thrust to deflect the tower downwind.

Best regards,