Simulation of transient gusts on the NREL5 MW wind turbine using CFD

Abstract

The performed work presents a procedure, implemented in the CFD-solver THETA, to propagate longitudinal transient gusts through a flow field by using a resolved gust approach. Both, the gust strike of a 1-cos()-gust and an extreme operating gust following the IEC-64100-1 standard, on the generic NREL 5MW wind turbine at rated operating conditions are investigated with CFD. The impact of both gusts on pressure distributions, rotor thrust, rotor torque, and flow states on the blade are examined and quantified. The flow states on the rotor blade before the gust strike and at maximum and minimum gust velocity are compared. An increased blade loading is detectable in the pressure coefficients and integrated blade loads. The friction force coefficients indicate the dynamic separation and re-attachment of the flow during the gust.