激波边界层干扰下曲壁结构气弹响应特性研究

Aeroelastic responses of curved panels under shock wave/boundary layer interaction

  • 摘要: 激波边界层干扰下飞行器曲壁蒙皮的非线性颤振问题,因涉及流动分离与几何大变形强耦合,目前尚缺乏系统的流固耦合动力学认识。为揭示该耦合系统的非线性气动弹性机理,本文建立了一种基于N-S方程与冯·卡门非线性板理论的双向分区流固耦合数值模型,系统研究了曲率系数H/h及激波冲击位置对二维曲壁板气动弹性响应的影响。结果表明:曲壁板变形呈前后反向特征,且相对于激波冲击位置具有显著非对称性,其中凸曲率壁板平均变形向下偏移,后缘变形量约为前缘的六到七倍,而凹曲率壁板向上偏移,前缘变形量约为后缘的四到五倍;随曲率增大,流动分离区延长,壁板颤振振幅增大,当|H/h|从零增至五时,凸曲率壁板四分之三位置处平均变形扩大四倍壁厚,凹曲率壁板则减小一倍壁厚,且凹曲率壁板平均变形普遍小于凸曲率;当曲率增大至一定程度时(本文研究条件下|H/h|增大到三),壁板颤振消失,系统转变为定点稳定状态。激波冲击位置对曲壁板振动响应的影响呈非线性规律,冲击点靠近两端时系统收敛至定点稳定,且越靠近下游收敛越快、静态变形越小;冲击点位于中心时平均变形和颤振幅值均最大,向两端逐渐减小;颤振发生与终止的临界冲击点不对称,偏向下游时颤振参数区间缩减四分之一。研究结果可为高速飞行器曲壁结构的气动弹性设计与流动控制提供理论参考和数据支撑。

     

    Abstract: Shock wave/boundary layer interaction (SWBLI) is a complex flow phenomenon frequently encountered during high-speed flight, which can induce flow separation and subsequent structural flutter, posing a severe threat to flight safety and aerodynamic performance. The nonlinear flutter of curved panels under SWBLI involves strong coupling between flow separation and large geometric deformation, yet a systematic fluid-structure interaction (FSI) understanding of this coupled system remains lacking. To reveal the underlying nonlinear aeroelastic mechanisms, a partitioned two-way FSI numerical model is established, coupling the unsteady compressible Navier-Stokes equations with the von Kármán nonlinear plate theory. The effects of the curvature coefficient and the shock impingement location on the aeroelastic response of a two-dimensional curved panel are systematically investigated. The results show that the curved panel exhibits a deformation pattern with opposite signs in the front and rear portions, and significant asymmetry relative to the shock impingement location: for convex curvature, the mean deflection is downward with the trailing-edge displacement about 6-7 times that of the leading edge, while for concave curvature, the mean deflection is upward with the leading-edge displacement about 4-5 times that of the trailing edge. As the curvature increases, the flow separation region lengthens and the flutter amplitude grows; specifically, as |H/h| increases from 0 to 5, the mean deflection at the 3/4 chord of the convex panel increases by 4 panel thicknesses, whereas that of the concave panel decreases by 1 thickness, and the concave panel consistently exhibits smaller mean deflection than the convex one. When |H/h| reaches 3, flutter vanishes and the system transitions to a fixed-point stable state. Furthermore, the influence of the shock impingement location is nonlinear: when the impingement point is near either end, the system converges to a fixed-point stable state, with faster convergence and smaller static deformation as the point moves further downstream; the maximum mean deflection and flutter amplitude occur when the shock impinges at the panel centre and decrease towards both ends. The critical impingement locations for flutter onset and termination are asymmetric about the mid-point, and the flutter parameter range shrinks by one-quarter when the impingement point shifts downstream. These findings can provide theoretical reference and data support for the aeroelastic design and flow control of curved-wall structures in high-speed vehicles.

     

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