An in-depth quantitative analysis of wind turbine blade tip wake flow based on the lattice Boltzmann method.

Abstract

With the continuous increase in the total quantity and quality of wind energy used by society, the aerodynamic complexity of wind turbine impellers has also gradually increased. This requires a more accurate analysis and understanding of the aerodynamic performance of important parts of the wind turbine impeller. The blade tip vortex is undoubtedly one of the most important issues. This article used the state-of-the-art lattice Boltzmann method (LBM), combining large eddy simulation (LES) and wall-adapting local-eddy (WALE) model, to investigate the unsteady flow characteristics of the blade tip region due to impeller wake for a wind turbine. The trend of this calculation result is consistent with the experimental data, both for the axial force and the torque on the impeller. Therefore, it indicates the calculation model of LBM is reasonable and effective. The relevant in-depth results clearly showed the dynamic stability of a spiral structure will increase as operating conditions continue to advance and it is also synchronously affected by the tower wake flow structures. The fluctuation amplitude of the static pressure value on both sides of the impeller gradually decreases with time. The distribution of static pressure near the leading edge of the tip is very different for each blade due to the influences of turbulence intensity and the tower shadow effect. The random minor fluctuations of the axial force and torque both exhibit similar characteristics, and the overall torque is more sensitive to random changes in the tip vortex on the impeller surface.