气动减阻表面对平板边界层影响

The Influence of Aerodynamic Drag Reduction Surface on the Boundary Layer Over a Finite Flat Plate

基于微纳米材料的气动减阻与疏水防冰混合涂层技术,旨在通过先进表面材料的参数化设计,以减缓大型风力机叶片等的气动载荷,提升气动性能。文中通过构建边界层精确测量技术和边界层特征参数辨识方法,结合近壁流动频谱特征,研究分析了一种减阻涂层对有限长平板边界层流动的影响。研究结果表明,减阻表面的微米级结构促使边界层粘性底层形成低雷诺数分离泡和脱体微旋涡。相较于金属固壁表面,气动减阻表面层流边界层在0.1 mm尺度内的微分离泡和微旋涡,对底部流动阻滞起到疏导作用,增强了层流稳定性,从而推迟边界层转捩。通过降低固壁摩擦阻力,进一步降低边界层导致的型阻,使得气动减阻表面流动的总阻力得以减少。

The micro-nano materials based hybrid coating technology of aerodynamic drag reduction and anti-icing aims to reduce the aerodynamic load and improve the performanceof large wind turbine blades through the parametric design of advanced surface materials.Adopting precise measurement technology and characteristic parameter identification method for boundary layer,combined with the spectrum characteristics of near wall flow,the effect of drag reduction coating on the boundary layer flow over a finite flat plate is studied.The results show that the drag reduction surface micro-structure promotes the formation of laminar separation bubbles at low-Reynolds-number and micro-vortex in the viscous sublayer;compared with the metal solid wall surface,the separation bubbles and micro-vortex in laminar boundary layer on the drag reduction surface at the scale of 0.1 mm play a role of facilitating the bottom flow retardation,enhancing the laminar stability,and thus delaying boundary layer transition;the total drag of the coating surface flow can be reduced by reducing the solid wall friction drag and further reduce the form drag caused by the boundary layer.