Investigation on the Influence of Bionic U-Shaped Groove Layout on Airfoil Stall Characteristics

To investigate the impact of surface patterns on the stall characteristics of airfoils, the NACA0012 airfoil was selected as the research object. Using the transition SST (γ-Reθt) turbulence model, a U-shaped groove layout was proposed, which was based on transverse, longitudinal, and herringbone grooves. Numerical simulation was conducted. The physical mechanism was analyzed, and the effects of groove depth, width, and arc angle on stall control were investigated. The results indicate that the critical angle of attack initially increases and subsequently decreases as the three geometric parameters increase. The critical angle of attack increases by a maximum of 18.75%, and all grooved airfoils delay stall to varying degrees. The flow field analysis demonstrates that as the airflow traverses the groove, small-scale eddies develop within and approach the center line, resulting in a pair of counter-rotating induced vortices of equal intensity on the groove surface. This effectively delays airfoil stall, alleviates the adverse pressure gradient at high angles of attack, and enhances energy exchange and mixing between the boundary layer and mainstream flow.