Bio-Inspired Asymmetric Airfoil Design Based on the Wind Energy Quality and Flow Field Spatio-Temporal on the Vertical Axis Wind Turbine Rotor Plane

Abstract

The airfoil design and energy efficiency optimization of vertical axis wind turbines (VAWTs) have made rapid progress, but most studies have not considered the difference in wind energy quality between the upwind and downwind regions of VAWTs. This study evaluates the distribution characteristics of wind energy quality in the upwind and downwind region of the H-type VAWT rotor plane. Lagrangian coherent structure (LCS) and dynamic mode decomposition (DMD) are used to investigate the attenuation principle of wind energy quality. According to the efficient hydrodynamic performance of Dall's porpoise at the positive angle of attack, a systematic and objective bionic airfoil design method is proposed. Results show that: (1) The wind energy quality in the upwind region of the VAWT is significantly better than the downwind region. At the tip speed ratio (TSR) of 1.2, the downwind wind speed is only 55.8% of the upwind speed. (2) The bio-inspired airfoil achieves a higher overall wind energy utilization rate than the NACA 0018 airfoil. (3) At TSR=0.5, the bio-inspired airfoil achieves a 42.3% increase in power coefficient. The design method of the asymmetric bio-inspired airfoil provides valuable insights for blade and airfoil optimization.

Keywords: VAWT, Wind energy quality, LCS, DMD, Asymmetric bio-inspired airfoil