Application of Asymptotic Acceleration Potential Method for the Calculation of Yawed Inflow Effect on Horizontal Axis Wind Turbine Rotor.

Abstract

We describe a method of calculating yawed inflow effects on horizontal axis wind turbine rotors. Yawed inflow brings about asymmetric induced velocity distributions on the rotor plane due to an inclined vortex wake construction. For the calculation of yawed inflow phenomena, an inviscid aerodynamic model based on pressure distributions is adopted. Under the assumptions of an incompressible inviscid irrotational flow, the pressure perturbation satisfies the Laplace equation and acts as an acceleration potential function. The rotor blades are represented by spanwise and chordwise pressure distributions composed of analytical first-order asymptotic solutions to the Laplace equation. Integration of the accelerations determines the velocities in the rotor plane. With these velocities the aerodynamic loads can be calculated. An advantage of this model is that evaluation of the relatively complicated unstationary effects from the vorticity in the wake is not necessary in the calculation procedure.