Prediction of Stochastic Blade Loads for Three-Bladed, Rigid-Hub Rotors

Accurately predicting wind turbine blade loads and response is important for the design of future wind turbines. The need to include turbulent wind inputs in structural dynamics models is widely recognized. In this paper, the Force and Loads Analysis Program (FLAP) code will be used to predict turbulence-induced bending moments for the SERI Combined Experiment rotor blade and the Howden 330-kWblade. FLAP code predictions will be compared to the power spectra of measured blade-bending moments. Two methods will be used to generate turbulent wind inputs to FLAP: 1. A theoretical simulation: the Pacific Northwest Laboratories (PNL) Simulation Theory; 2. Measured wind-speed data taken from an array of anemometers upwind of the turbine. Turbulent wind-speed time series are input to FLAPfor both methods outlined above. Power spectra of predicted flap-bending moments are compared to measured results for different wind conditions. Conclusions are also drawn as to the ability of the turbulence simulation models to provide accurate wind input to FLAP and to FLAP's ability to accurately simulate blade response to turbulence. Finally, suggestions are made as to needed improvements inthe theoretical model.