带外挂二元机翼颤振模态的转变

TRANSITION OF FLUTTER MODE OF TWO-DIMENSIONAL WING WITH EXTERNAL STORE

本文采用定常空气动力,对机翼外挂系统按频率重合理论进行颤振分析,从而确定最低颤振速度随外挂俯仰频率变化的颤振边界曲线。结果表明,可以根据固有振型的变化情况对颤振模态的转变做出工程判断。

By using the theory of frequency coalescence and steady aerodynamics, the wing store flutter problem is studied in the space of normal mode coordinates. It is found that for most cases, only two normal modes have predominant effects on the constitution of flutter mode. The flutter boundary which depicts the change of flutter speed vs store pitching stiffness is calculated with each two-normal-mode binary system to identify the evolution and transtion of wing-store flutter mode. The prerequisite information is only the normal mode data, which are the direct results of the ground vibration test or the routine vibration analysis. The results show that the estimating calculation can give the flutter boundary with reasonable accuracy, and the constitution and evolution of wing-store flutter mode can be determined from the node position of its normal modes. Especially, for the intersection of the two flutter branches, where the sudden change of flutter mode occurs, the frequency coalescence calculation can give a reasonable estimation.