A Numerical Study Of Tidal Current Turbine Combining Large Eddy Simulation With Actuator Line Method

This paper presents the numerical simulation of tidal current turbine.In addition,the optimization design and the model test in towing tank are carried out to validate the numerical results.For numerical work,the traditional Reynolds Averaged Navier-Stokes Method(RANS)and the hybrid method combining Large Eddy Simulation with Actuator Line Method(LES-ALM)are applied to predict the performance and the wake fields of the tidal turbine.The results of both two methods have a good agreement with the experimental data.Besides,avoid solving the severe velocity and pressure gradient near the wall surface,LES-ALM significantly reduces the computing cost and can take the advantage of LES to capture the detailed flow structure in turbine wake.Based on the LES-ALM,further studies has been carried out focusing on the impact of different flow conditions.Three flow conditions,uniform flow,stratified flow and turbulent flow are imposed on the inlet boundary and have a remarkable influence on the turbine wake.Furthermore,a solver coupling the tidal turbine and free surface is developed to study the influence of free surface and blockage effect.As a result,the blockage effect significantly improves the efficiency of tidal turbine.Considering the free surface effect,a standing wave occurs and elevates the surface height above the turbine,which impairs the effect of blockage effect and reduces the turbine efficiency.In short,this paper systematically present the theory and results of LES-ALM and applies this method on the study of tidal turbine in complex environmental flow conditions.The results reflect the characteristics of the performance and flow fields of single turbine and turbine array.