Wake characteristics in high solidity horizontal axis hydrokinetic turbines: a comparative study between experimental techniques and numerical simulations

Abstract

Hydrokinetic turbines utilizing renewable energy from water streams, such as tidal or river currents, offer a sustainable solution for electricity generation in remote coastal or fluvial regions. While there has been extensive research on the wake characteristics of low-solidity turbines, studies focusing on high-solidity turbines are limited. This study aims to address this research gap by characterizing the turbulent wake of a high-solidity, four-bladed hydrokinetic turbine using a combination of experimental and numerical approaches. Experimental investigations are conducted in two wind tunnel facilities, employing particle image velocimetry and hot-wire anemometry to measure and identify flow structures in the near-wake region. Additionally, the applicability of the actuator line method for high-solidity turbines is validated, considering the challenges posed by the higher blockage effect associated with such turbines. Numerical simulations are performed using an unsteady Reynolds-averaged Navier–Stokes approach, incorporating a full-geometry model of the rotating rotor and employing the actuator line concept for simplified modeling. The findings from this study provide valuable insights into the wake characteristics of high-solidity hydrokinetic turbines, contributing to the understanding of their performance and environmental implications.