A computational procedure for prebending of wind turbine blades

Prebending of wind turbine blades constitutes a viable engineering solution to the problem of tower clearance, that is, ensuring that during wind turbine operation there is sufficient distance between the rotor blades and the tower to avoid collision. The prebent shape of the blade must be such that when the turbine rotor is subjected to wind and inertial loads, the blades are straightened into their design configuration. In this paper, we propose a method for accurate prediction of the prebent shape of wind turbine blades. The method relies on a stand-alone aerodynamics simulation that provides the wind loads on a rigidly spinning rotor, followed by a series of structural mechanics simulations to determine the stress-free prebent shape of the blade. This procedure involves only one-way coupling between the fluid and structural mechanics, which avoids the challenges of solving the coupled fluidstructure interaction problem. The proposed methodology, which has no limitations on the blade geometry and structural modeling, is successfully applied to prebending of a 63-m offshore wind turbine blade. Copyright (c) 2011 John Wiley & Sons, Ltd.