Numerical simulation of wind tunnel wall effects on wind turbine flows

Abstract

A low-order panel method and a prescribed wake vortex model have been combined into a coupled model capable of assessing the basic effect of wind tunnel walls on wind turbine flow and performance. The wind tunnel walls are discretised into a series of panels, and sources distributed on these panels simulate the constraint effect of the wind tunnel walls. The wind turbine and its wake are represented by the prescribed wake model. The source strengths are related to the induced velocities at the panel control points due to the turbine vortex system by satisfying the boundary condition of zero normal velocity on the solid tunnel wall. The vortex-induced and source-induced velocities at the blade are summed to determine an interim turbine wake using the prescription functions. The effects of the disturbance velocities due to the source panels are then superposed upon the prescribed wake to obtain the final wake geometry under the influence of wind tunnel wall interference. The model developed in this study is compared with wind turbine wake measurements made in a low-speed wind tunnel. Generally, the model is found to compare well with experiment, although some discrepancies are noted. Finally, possible future improvements to the combined method are recommended. Copyright © 2001 John Wiley & Sons, Ltd.