A MODEL FOR UNSTEADY ROTOR AERODYNAMICS

Abstract An aerodynamic model for the simulation of unsteady flow past rotors of wind turbines is presented. The model consists of solving the unsteady, axisymmetric Euler or Navier-Stokes equations by a finite-difference method subject to volume forces determined from tabulated airfoil data. Results are compared to the blade-element momentum theory and experiments for the cases of a rotor with a prescribed constant normal load and steady as well as unsteady flows past the 2 MW Tjaereborg wind turbine. The model is found to be in better agreement with measurements than the momentum theory and in particular excellent agreement is obtained with dynamic in-flow phenomena from measured pitching transients.