Aerodynamic Analysis of the NREL 5-MW Wind Turbine using Vortex Panel Method

Abstract

The purpose of this study was to investigate if panel methods can be used to examine aerodynamic loads on wind turbine blades. Another aim was to find out the differences between the Lifting Surface Method, the Vortex Panel Method (a number of panels along the chord) and the Reduced Vortex Panel Method (one panel along the chord) when applied to horizontal axis wind turbines. Panel methods use vortex filaments or rings to model the surface of a solid body and the wake behind the wind turbine. Therefore, a grid was laid on the blades and the wake. That way for every blade the influence of all wakes and blades was taken into account. In this thesis the wind profile was uniform. Furthermore, incompressible, frictionless flow was assumed. The results for the NREL 5-MW wind turbine revealed that the Lifting Surface Method and the Reduced Vortex Panel Method produce similar force distributions along the blade (from root to tip). The forces obtained with the Vortex Panel Method are not only higher but also more accurate compared to Computational Fluid Dynamics, Blade Element Momentum and General Unsteady Vortex Particle data for the same blade. The principal conclusion was, the Vortex Panel Method is a suitable tool to investigate the aerodynamic loads on horizontal axis wind turbines with three blades.