Investigation of the effect of free-stream turbulence on paired vertical-axis wind turbines using wind tunnel testing and an actuator-line model

The aerodynamic interaction of vertical-axis wind turbines (VAWTs) in paired configurations can be advantageous in wind farms. However, these turbines operate in the atmospheric boundary layer which is characterised by high turbulence and may also face high-turbulence levels associated with downstream wakes. Therefore, the main goal of this study is to explore the impact of turbulence intensity on the efficiency of paired VAWTs, employing a combination of wind tunnel experiments and an actuator-line model (ALM) integrated in a URANS-based OpenFOAM solver. The present ALM employs aerodynamic coefficients derived from experimental dynamic measurements conducted on a pitching aerofoil. The wind tunnel tests suggest that paired VAWTs operating in turbulent inflow can experience advantages arising from both the mutual aerodynamic interaction between them and the effect of turbulence on the aerodynamic conditions on their aerofoils. Additionally, the ALM sheds light on the mechanisms that contribute to the enhanced power output of isolated and paired VAWTs in turbulent inflow conditions.