Recent improvements of actuator line-large-eddy simulation method for wind turbine wakes

Abstract

In a large wind farm, the wakes of upstream and downstream wind turbines can interfere with each other, affecting the overall power output of the wind farm. To further improve the numerical accuracy of the turbine wake dynamics under atmosphere turbulence, this work proposes some improvements to the actuator line-large-eddy simulation (AL-LES) method. Based on the dynamic k-equation large-eddy simulation (LES), this method uses a precursor method to generate atmospheric inflow turbulence, models the tower and nacelle wakes, and improves the body force projection method based on an anisotropic Gaussian distribution function. For these three improvements, three wind tunnel experiments are used to validate the numerical accuracy of this method. The results show that the numerical results calculated in the far-wake region can reflect the characteristics of typical onshore and offshore wind conditions compared with the experimental results. After modeling the tower and nacelle wakes, the wake velocity distribution is consistent with the experimental result. The radial migration velocity of the tip vortex calculated by the improved blade body force distribution model is 0.32 m/s, which is about 6% different from the experimental value and improves the prediction accuracy of the tip vortex radial movement. The method proposed in this paper is very helpful for wind turbine wake dynamic analysis and wind farm power prediction.