Numerical Investigations on Dynamic Stall Characteristics of a Finite Wing

有限翼展机翼动态失速特性的数值研究

The paper examines the dynamic stall characteristics of a finite wing with an aspect ratio of eight in order to explore the 3D effects on flow topology,aerodynamic characteristics,and pitching damping.Firstly,CFD methods are developed to calculate the aerodynamic characteristics of wings.The URANS equations are solved using a finite volume method,and the two-equation k-ωshear stress transport(SST)turbulence model is employed to account for viscosity effects.Secondly,the CFD methods are used to simulate the aerodynamic characteristics of both a static,rectangular wing and a pitching,tapered wing to verify their effectiveness and accuracy.The numerical results show good agreement with experimental data.Subsequently,the static and dynamic characteristics of the finite wing are computed and discussed.The results reveal significant 3D flow structures during both static and dynamic stalls,including wing tip vortices,arch vortices,Ω-type vortices,and ring vortices.These phenomena lead to differences in the aerodynamic characteristics of the finite wing compared with a 2D airfoil.Specifically,the finite wing has a smaller lift slope during attached-flow stages,higher stall angles,and more gradual stall behavior.Flow separation initially occurs in the middle spanwise section and gradually spreads to both ends.Regarding aerodynamic damping,the inboard sections mainly generate unstable loading.Furthermore,sections experiencing light stall have a higher tendency to produce negative damping compared with sections experiencing deep dynamic stall.

研究了展弦比为8的有限翼展机翼的动态失速特性,以深入了解三维效应对流场结构、气动特性和俯仰阻尼的影响。首先,构建了计算流体动力学方法来模拟机翼的气动特性,采用有限体积法求解URANS方程,通过k-ω(Shear stress transport,SST)两方程湍流模型来考虑黏性效应。然后,采用上述CFD方法模拟了静态平直机翼和俯仰振荡尖削机翼的气动特性,数值结果与试验数据之间良好的一致性验证了CFD方法的有效性和准确性。最后,计算分析了有限翼展机翼在静态及动态状态下的气动特性。研究表明:无论是静态失速还是动态失速过程,机翼流场中均出现了显著的三维流场结构,包括翼尖涡、弓形涡、Ω涡和环形涡等,这些现象导致机翼的气动特性显著区别于二维翼型,具体表现为:附着流阶段升力线斜率减小、失速角增大以及失速更为平缓;气流分离最先出现在机翼中部,随后逐渐向两端扩展;至于气动阻尼特性,不稳定载荷主要由机翼内段产生;此外,与深度失速的翼段相比,轻度失速的翼段更易产生负阻尼。