Large-eddy simulation and experimental study on the turbulent wake flow characteristics of a two-bladed wind turbine

Abstract

Large-eddy simulation (LES) with fully resolved rotor method (FRM) is applied to explore the turbulent wake flow characteristics and vortex evolution laws of a two-bladed horizontal-axis wind turbine. Relevant wind tunnel experiments have been done based on time resolved particle image velocimetry (TRPIV) technique. The simulation results are validated by the experimental data and they are in good agreement. The axial average velocity, turbulent kinetic energy, shear Reynolds stress, and vortex structure of the wind turbine wake are analyzed based on the comparison of LES results and experimental data. It is observed that the wake diameter of wind turbine enlarges with the increase of tip speed ratio (TSR). Turbulent kinetic energy meets its minimum value when x / R =2.0. Shear Reynolds stress appears a positive peak in the near wake when x / R <2.0, and the value of shear Reynolds stress decreases along the axial direction. The blade tip vortex dissipates more quickly than the central vortex in the wind turbine wake, and the gradient of the relationship curve between the blade tip vortex core position and the vortex age decreases as the TSR increases. With the increase of TSR, the thrust coefficient increases, and the power coefficient increases first and then decreases. The present work proves that LES with FRM could calculate wind turbine turbulent wake flow with a high accuracy.