Experimental Comparison of the Wake of a Vertical Axis Wind Turbine and Planar Actuator Surfaces

Abstract

Wind tunnel experiments on a scaled vertical axis wind turbine (VAWT) and square porous plate with a porosity of 64% are conducted in the W-tunnel of TU-Delft. The VAWT thrusts in axial and lateral directions are measured with an in-house load cell system based on moment conservation. Wake of the VAWT in tip speed ratio of 1.5 and 2.5 and the porous plate is measured with the robotic particle image velocimetry technique, which enables a three-dimensional velocity measurement in a combined volume encompassing from 1 diameter upstream to 3 diameters downstream. Counter-rotating vortex pairs in VAWT wake and the wake shape deformation and deflection are discussed, which are related to the lateral thrust. A square porous plate inducing a similar axial thrust is compared, which has the same shape as the cross-section of the VAWT. Wake of the right porous plate with a yaw angle of 15? is investigated, which produces similar deflection as the VAWT.