Experimental and numerical investigations of hydrodynamic performance for horizontal-axis hydrokinetic turbines

Abstract

This paper presents both experimental and numerical investigations of the hydrodynamic performance of Horizontal-axis Hydrokinetic Turbines (HAHTs) using experimental methods and Computational Fluid Dynamics (CFD) approaches, respectively. The innovative aspect of this study lies in the consistency of the results, achieved by aligning the method used in the CFD analyses for Hydrokinetic Turbines (HKTs) and airfoil profiles with experimental data. For this purpose, 2-D CFD analyses were first conducted with blade section geometries (Eppler 395 and S1210), which are commonly used in HKT designs. The aerodynamic characteristics (CL and CL/CD) of these blade sections were computed and compared with the experiments. Subsequently, a three-dimensional (3-D) turbine geometry, featuring three different pitch angles (PAs), was simulated using CFD, and the results were compared with experimental data obtained under the same operating conditions in the Emerson Cavitation Tunnel (ECT) at Newcastle University. The comparisons showed good agreement while the maximum relative error was calculated less than 10 % for the power coefficient (CP) of the turbine with a PA of 0 degrees. For the other PA (8 degrees), the maximum relative error was 11 % for CP and 14 % for the thrust coefficient (CT). The CFD investigations of HKTs revealed that the Detached Eddy Simulation (DES) model has less relative errors compared to the other turbulence models at the same Tip Speed Ratio (TSR) values, while the Sliding Mesh (SM) method describing rotation gives more consistent and closer results to the experiments, with the investigation of y+ point of view.