变形振荡翼的动态失速特性研究

Investigation of dynamic stall properties of the deformed oscillating airfoil

该文针对NACA0012振荡翼型动态失速流动现象,采用二维非定常数值模拟的方法,在考察湍流模型和网格分辨率影响的基础上,对比了动网格、多参考系动流域和网格点直接更新法模拟翼型动态失速引起气动力非线性迟滞特性的能力,并侧重分析了轻失速和深失速工况、刚性翼和圆弧变形翼的升阻力曲线及涡量场随攻角变化的演化过程。结果表明:(1)三种模拟振荡翼流场的数值计算方法是等价的;(2)轻失速和深失速工况下的流场结构区别明显,轻失速在振荡周期内流场结构变化不大,而深失速流场出现了明显的分离涡结构,变化剧烈;(3)不同大小变形量对翼型升力系数有着明显影响;合适的变形量大小能够减弱翼型下俯过程中的升力振荡现象;变形量的增大可抑制上仰过程中涡的分离,从而推迟了深失速迟滞效应的发生。

The dynamic stall flow phenomenon of a NACA0012 oscillating airfoil is studied with two dimensional unsteady numerical simulation method.Based on the investigation of the effects of turbulence model and grid resolution,the aerodynamic non-linear hysteresis characteristics caused by dynamic stall of airfoil are simulated by dynamic grid,multi-reference dynamic basin and grid point updating method.The evolution of lift and drag curves and vortices fields with angle of attack for rigid and the circular deformed airfoil under light and deep stall conditions are analyzed emphatically.The results show that:(1)Three nume-rical methods for simulating the flow field of oscillating airfoil are equivalent.(2)The flow field structures of light stall and deep stall are obviously different,and the flow field structure of light stal l has little change in the oscillating period,while the flow field of deep stall has distinct separated vortices structure,which change s dramatically.(3)The lift coefficients of airfoil are obviously affected by different deformations.Appropriate deformations can re duce lift oscillation during airfoil downward pitching,and the increase of deformations can restrain the separation of vortices durin g the upward pitching process,thus delaying the occurrence of hysteresis effect indeep stall.