直升机着陆过程中动不稳定现象分析

Research on Dynamic Instability during Helicopter Landing

通过分析某型直升机在尾起落架着地时出现的机体异常振动,建立了一种以直升机状态及操纵参数为基础,以时频分析为手段的地面动不稳定性方法。首先分析异常振动与正常振动的异同点,通过时频分析获得引起异常振动的现象特征。通过频率根源查找,最终找出引起异常振动的原因为机体的俯仰模态与旋翼摆振后退型耦合引起的一种动不稳定现象,并对引起该种现象的原因加以分析,给出改进措施,为今后的直升机动不稳定试飞技术提供参考。

This paper analyzed the abnormal vibration of a helicopter during landing gear. A ground dynamic instability method based on helicopter condition and control parameters were established. By means of time-frequency analysis, the characteristic of abnormal vibration was obtained by comparing normal vibration with abnormal vibration. The causes of abnormal vibration were found by the frequency root finding, which is dynamic instability caused by the backward mode of the airframe and the back coupling of the rotor. The reasons for this phenomenon were analyzed, and the improvement measures were given to provide a reference for future helicopter test flight technology.