Dynamic Rotor Loads of a Wind Turbine via Hand-Held Calculators

A straightforwar d method has been developed for the calculation of wind-turbine dynamic loads using a closed-form analytical model. This paper describes the model and provides an example calculation. Blade natural frequencies are used to identify an analytical blade model to represent the complex, flexible rotor blade. The rotor and wind parameters are identified and calculated, and the equations giving collective and cyclic blade trajectories are described. The corresponding root bending moments are calculated for the example set of conditions. The in-plane coupling due to Coriolis force and flapping velocity is then assessed. Limitations of the theory and method are described, with simple procedures to assess their effects.