Wake meandering: A pragmatic approach

The phenomenon of wake meandering is long known empirically, but has so for not been treated in a satisfactory manner on the wind turbine load modelling side. We present a consistent, physically based theory for wake meandering, which we consider of crucial Importance for the overall description of wind turbine loadings in wind forms. In its present version, the model is confined to single wake situations-including a simple heuristic description of wake interaction with a reflecting surface. Contrary to previous attempts to model wind turbine wake loading, the present approach opens for a unifying description in the sense that turbine power and load aspects can be treated simultaneously. This capability is a direct and attractive consequence of the model being based on the underlying physical process, and it potentially opens for optimization of wind form topology, wind form operation, as well as control strategies for the individual turbine. The application of the proposed dynamic wake meandering methodology with existing aeroelastic codes is straightforward and does not involve any code modifications. The strategy is simply to embed the combined effect of atmospheric turbulence, added wake turbulence and the intermittent 'turbulence contribution, caused by wake meandering, in files replacing the traditional turbulence file input to aeroelastic computations. Copyright (C) 2008 John Wiley & Sons, Ltd.