Accelerated computation of the wake of a horizontal axis wind turbine in unsteady operation using the vortex approach

This article aims to propose an approach for modeling the unsteady behavior of a horizontal axis wind turbine. The unsteady operation is supposed to be the consequence of a rapid variation of the pitch angle of the blades or the load of the wind turbine. The used vortex model has a limited number of elements, in order to reduce the time and volume of the required numerical computation. The wake behind the wind turbine is considered to be composed of small series of vortex rings in the near wake and one semi-infinite vortex cylinder in the far wake. This model is coupled with a blade element method, which allows fast determination of the momentum and power of the wind turbine. Field measurements of the Tjaereborg wind turbine are used as a reference for the validation of the proposed model. The results obtained with the numerical simulation show a good agreement with the measured experimental data