Response of the Mod-OA Wind-Turbine Rotor to Turbulent Atmospheric Wind.

摘要

The major focus of this paper will be the description of the fluctuating loads caused by the atmospheric turbulence. The wind turbulence inputs used in this study are determined in three basic modeling steps. First, the turbulent velocity field is characterized by a model which provides the correlation between velocity components at different spatial positions and at different times. Second, the velocity field is approximated in the rotor disk plane using a series expansion which includes terms that are uniform across the rotor disk, gradient terms which vary linearly across the disk, and terms which vary quadratically across the disk. All of these terms are time dependent. In the third step, simple rational spectral representations are determined which approximate the derived correlation model for these turbulence components. The Von Karman model is used to characteize the correlation between velocities at spatially separated points. Quasi-steady linear aerodynamic theory is used to compute the forces on the rotor blades of the Mod-OA wind turbine operating in a turbulent flow. The blade used for these computations is the fiberglass blade in place on the Mod-OA turbine as of November 1981. Using the combined turbulence and aerodynamic model the following rotor responses are computed: thrust, torque, pitch and yaw moments, and blade root bending moments. These computations were made for the case of fixed pitch operation and incorporate the influence of a linear mean wind shear. Results presented include power spectral density plots of the wind and turbine outputs described above for three different mean wind conditions. There is a comparison of the various responses to determine the relative importance of the turbulence inputs on rotor blade loads. (ERA citation 08:033592)