Lift-Induced Wake Re-Energization for a VAWT-Based Multi-Rotor System

Abstract

This study explores the performance and near-wake dynamics of a VAWT-based Multi-Rotor System in both its original configuration and in the presence of external lift-generating devices, specifically employed for wake control operations. The wake of a scaled VAWT-based MRS was measured in a wind tunnel using Particle Tracking Velocimetry. Lift-generating devices, including a 3-element cascading wing on top and a single-element wing in the middle of the MRS, were used to enhance wake control and deflection. Measurements in the near-wake revealed notable differences between configurations with and without these devices. Without them, the wake remained concentrated in the actuator surface’s projected downstream area, with minimal crossflow diffusion. Conversely, the configuration with lift-generating devices exhibited significant wake deformation, including axial expansion and lateral contraction, promoting streamwise momentum recovery. As a result, increased power recovery was found downstream of such a system compared to the clean MRS. These findings underscore the potential of such systems, particularly when equipped with lift-generating devices, to manipulate wake dynamics and enhance wind farm efficiency, thereby advancing innovative wind energy solutions.