Experimental Performance Assessment of a Crossflow Turbine for Energy Generation From Moving Water

Abstract Crossflow tidal turbines are a promising technology for harnessing energy from tides or riverine flows. They offer flexibility in deployment, either individually or in arrays. However, design selection must consider real working conditions, such as low flow velocities and depth levels, to guarantee optimal power output. Therefore, it is crucial to understand the effects of different flow velocities and free surface proximity. In this study, a commercially available H-Darrieus wind turbine was experimentally assessed as a vertical crossflow turbine under several flow-induced free-rotation conditions using an electromagnetic brake as a torque regulator. Experiments were conducted in the high-speed towing tank of Davidson Lab at Stevens Institute of Technology, investigating the effects of various Reynolds-Froude number combinations. Turbine performance was assessed based on the power coefficient and the maximum resistive torque it could sustain while continuously spinning. The results demonstrated that increasing Reynolds number enhances the power coefficient, aligning with findings in the literature. However, closer proximity to the free surface caused a decline in performance, contradicting some previously reported studies. These findings provide valuable insights into the underlying hydrodynamics affecting cross-flow turbines, contributing to improved design and deployment strategies for free-surface and farm configurations.