跨声速嗡鸣诱发机理及其失稳参数研究

Study on the mechansim and instability parameters of transonic buzz

跨声速嗡鸣问题是现代飞行器设计和使用过程中的拦路虎,会造成操纵面的损坏或严重变形。目前嗡鸣研究的局限在于缺乏预测嗡鸣触发参数范围的有效方法,难以指导工程实践。本文通过基于ROM的气动弹性分析模型和CFD/CSD时域仿真方法,研究了三种类型嗡鸣的触发条件及其参数的物理意义。相关结果表明,三种嗡鸣本质都是亚稳定的流动模态和结构模态耦合诱发结构失稳。降阶模型进一步揭示嗡鸣的触发要求流动的稳定裕量足够低(往往在抖振边界附近),同时结构频率在开环伯德图的零极点频率之间。该研究有助于对嗡鸣物理更深入的理解以及提出新的嗡鸣抑制方法。

Transonic control surface buzz is an obstacle in the designing and using processes of modern aircraft, which can cause damages or serious deformation of the control surface. The limitation of previous investigations on transonic buzz is that they failed to predict the instability boundaries, which are key parameters to aircraft designers. In this paper, towards the typical buzz cases (A/B/C types), the inducing flow and structure conditions as well as the physical meaning of these parameters are studied by using the ROM-based aeroelastic analysis model and CFD/CSD time domain simulation method. Relevant results show that these buzzes are all the result of the instability on the structural branch owing to the coupling effect between the least-stable fluid mode and the structural mode. The eigenvalue analysis further reveals that the occurrence of transonic buzz requires the followings:(i) the stability margin of the flow is low enough (often near transonic buffet onset and offset conditions);(ii) the structural frequency is between those of zero-pole points of the open-loop Bode graph. This study helps to understand the physics and to propose new suppression methods for transonic buzz.