The interface flange from the tower to the yaw bearing is designed to stiffness specifications required by the yaw bearing and also to peak load and fatigue life requirements imposed by the turbine/tower system and wind class.
The tower top design eliminates fatigue cracking concerns by eliminating welds in the structure connecting the tower top flange to the top of the tower legs. Both peak and fatigue load in the structure are further reduced in the tower top connection by aligning the load paths with the central axis’ of the tower legs.
Turbine manufactures can take advantage of the tower top flange by using it as the shipping base for the nacelle. This allows for:
· all yaw bearing bolts to be fully assembled and torqued in a shop environment.
· Simplify field installed connection bolts on top of the tower
· Reduce cost of current shipping platform required for nacelle shipment
|
