Large-eddy simulation of serration effects on a rotating Wells turbine in transient inflow

Abstract

In recent years, global energy demand has continued to increase, and international competition over securing energy resources has begun to intensify. Under these circumstances, various research initiatives and demonstration projects have been launched to promote the adoption of renewable energy for stable energy supply. This study focuses on oscillating water column (OWC) power generation as a viable form of renewable energy utilization and attempts to optimize blade shapes to improve the performance of the Wells turbines used in OWC system. This study employed Large Eddy Simulation (LES) to analyse the unsteady turbulent flow passing through a rotating Wells turbine. This calculation clarifies the dependence of the wake structure and turbine performance on changes in the position and shape of the serrated blade profile. In this study, a turbine without serrations was employed as the reference model. Compared to this, analyses were performed on turbine models with serrations added to blade tip side and rotor hub side, respectively. By performing LES on these models incorporating the effects of turbine rotation using MRF (Multiple Reference Frame), analysis of the unsteady flow passing through the rotating turbine was conducted. In this study, in addition to the qualitative flow behavior through the flow visualization around the turbine, quantitative comparisons were made between the models regarding the dependence of the flow coefficient on pressure, torque, and turbine efficiency. The insights gained from this study contribute to the optimization of the Wells turbine, it becomes feasible to address various issues such as improving efficiency and reducing noise.