INFLUENCE OF DYNAMIC STALL IN THE AERODYNAMIC STUDY OF HAWTS

In order to evaluate the global unsteady loads on a HAWT, subjected to dynamic stall, some semi-theoretical models have been introduced in the static force calculation program FORAER developed at the Department of Fluid Mechanics of the Vrije Universiteit Brussel. The models are derived from retreating blade stall on helicopters. Among models, the Boeing-Vertol, Strickland, Machielse, Favier, ONERA models have been used. The purpose of this study is to gain better knowledge of HAWT behaviour under the dynamic stall influence, and to evaluate the surplus or energy loss with respect to steady flow. Comparison is made between numerical and experimental results for two prototype HAWT, the VUB H8.5 located in Zeebrugge and a 500 kW Windmaster at Bergen op Zoom.