仿座头鲸前缘凸起数对NACA 634-021翼型失速控制机理影响研究

The Effect of Humpback Whalelike Leading-edge Protuberances Number on Stall Control Mechanism of NACA 634-021 Airfoil

失速是翼型绕流中一种常见的现象,导致升力系数快速下降,阻力系数快速升高,致使翼型性能大幅度下降。近年来,相关研究表明仿座头鲸前缘凸起可以有效延缓失速或者改善失速后翼型气动性能。因此,本研究选取与座头鲸鳍肢截面相似的翼型NACA 634-021为基础翼型,在基础翼型上通过布置不同凸起数来探究仿座头鲸前缘凸起对翼型失速控制机理。在雷诺数为1.8×10^5条件下,采用雷诺时均斱法,选取考虑转捩的SST k-ω湍流模型,对不同攻角翼面迚行三维数值模拟,通过对比基础翼型和单凸起翼型升、阻力系数以及丝线可视化实验结果,验证数值模拟的正确性。然后迚行双凸起和连续凸起翼型数值模拟研究,结合绕流特性对双凸起及连续凸起翼面迚行深入分析,研究结果表明仿座头鲸前缘凸起结构具有改善失速特性并提高失速后的气动性能的能力,但是由于凸起数的不同,作用机理不同,失速控效果不同。本研究为水轮机导叶、风力机叶片等复杂流体机械失速控制提供了一种新的设计思路。

Stall is a common phenomenon in the flow around airfoil,which leads to the rapid drop of lift coefficient and the obvious increase of drag coefficient,resulting in the severe decrease of airfoil performance.In recent years,relevant studies show that the airfoil with humpback whalelike leading edge protuberances can effectively delay stall and improve aerodynamic performance after stall.Therefore,in this study,an airfoil NACA 634-021,which is similar with the fin limb section of humpback whale,is selected as the basic airfoil.Different number of leading-edge protuberances are arranged on the basic airfoil to explore the control mechanism on stall.Under the condition of Reynolds number of 1.8×10^5,three-dimensional numerical simulations on different angle of attack airfoil are carried out through Reynold-averaged Navier-Stokes method using SST turbulence model considering transition.The accuracy of numerical simulation is verified using the the lift and drag coefficients as well as tuft visualization experiment results of basic and single leading-edge protuberance airfoils.Then,double and continuous leading-edge protuberance airfoils are investigated through numerical simulation.The results reveal that the humpback whalelike leading-edge protuberance could improve stall characteristics and enhance the aerodynamic performance after stall.However,the number of leading-edge protuberances has an obvious effect of stall control mechanism.This study provides a new design idea for blades to control stall in hydraulic machinery,such as guide vanes in hydraulic turbines,blades in wind turbines.