Numerical Investigations of Nacelle Anemometry for Horizontal Axis Wind Turbines

This paper presents a numerical method for investigating nacelle anemometry of an horizontal axis wind turbine. The flowfield around the turbine and nacelle is described by the Reynolds averaged Navier-Stokes equations. The k–ε model has been chosen for the closure of time-averaged turbulent flow equations. The turbine is modeled using the actuator disk concept. Most of the nacelle region is represented by it real geometrical shape as wall boundary, except for the cooling system (radiator) of the electric generator which is modeled as a permeable surface with some prescribed pressure jump. The main purpose of this paper is to establish the relationship between the nacelle wind speed and free stream wind speed for an isolated turbine, in order to assess the impacts of the variation of some operational parameters (e.g. blade pitch angle changes), as well as atmospheric turbulence, on this relationship. The simulation results have been compared with the experimental data (from a typical stall-controlled wind turbine rated more than 600kW and comercially available). In general, good qualitative agreements have been found proving the validity of the proposed method. However, the level of accuracy is still insufficient for use in power performance testing. On the other hand, the numerical method might be a useful tool for locating nacelle anemometers.