推进式螺旋桨振动应力特性飞行试验与分析

根据某型飞机单发推进式螺旋桨结构与载荷特征,利用有限元分析确定桨叶振动应力危险部位,设计加装无线电遥测系统进行应变测试,并根据螺旋桨振动应力的影响因素确定飞行试验科目。测试系统装机后开展不同条件的飞行试验,获得了螺旋桨在典型工作状态下的静应力和动应力。分析表明静应力基本随高度、速度和滚转角的增大成增大趋势,但在高度5 000 m静应力随滚转角的变化趋势并不明显,动应力随速度增大明显增大,随高度和滚转角增大缓慢增大;通过Compell图和多状态频谱分析发现慢车状态1阶动频与转速2倍频接近,存在共振风险,并给出了改进建议。

In-flight Vibratory Stress Measurement and Evaluation of a Pusher Propeller

According to the structure and load characteristics of a pusher propeller equipped on a single engine airplane, the hazardous locations were determined based on finite element analysis. A telemetry system was designed and installed for strain measurement of the propeller blades. Flight test including different operating conditions was finished after test system installation. The variation rules of the vibratory stress with flight parameters were obtained. The results indicate that the static stress basically increases with altitude, air velocity and roll angle. However, at the altitude 5000m the variation trend of static stress with roll angle is not so clear. The dynamic stress increases with air velocity significantly, and with altitude and roll angle slowly. A resonance effect was discovered due to the close of the 1^st order dynamic frequency and the double rotor frequency in idle condition. Recommendation for the improvement of the resonance situation was provided as well.