含气穴效应的起落架落震动力学研究

针对某无人机前起落架在落震试验中地面载荷上升阶段出现的异常波动现象，通过对落震试 验结果中缓冲器压缩状态和地面载荷关系的分析，判断该现象是由于缓冲器主油孔较小，主 油腔中的气泡不能顺利转移到空气腔导致。建立了包含缓冲器主油腔气穴效应的起落架落震动 力学模型，采用数值分析方法求解了该模型的动力学特性，计算结果与试验结果符合较好。 通过震荡方法排除缓冲器主油腔中气穴后，落震试验得出的试验结果和不包含气穴效应的模 型计算结果符合。落震试验对比表明：缓冲器轴向载荷波动现象由气穴效应引起；通过消除 气穴方法后，起落架地面垂向载荷峰值下降0.3 kN，起落架系统缓冲效率提高2%。

Study on Landing Gear Drop Dynamics with Cavitation Effect

In the drop test for nose gear of a certain type of unmanned aerial vehicle, unu sual fluctuation of load is spotted when ground load increases. The relations be tween landing damper compression and ground load in the drop test are analyzed, and the conclusion goes that the main oil hole of the damper is too small to enable bubbles to move from main chamber to the air chamber. Landing gear drop test dynamics model including the effect of main oil chamber cavitations is built. The dynamics characteristics of the specific model are studied through numerical analysis, and the results are consistent with test results. After cavitations inthe main oil chamber are eliminated, the results of actual drop test are quite similar with those of theoretical simulations using cavitation free model. By comparing two methods of drop test, the conclusion is that axial load fluctuation is caused by cavitation. As soon as the cavitation is eradicated, the peak value of the vertical land load decreases by 0.3 kN, and the damping efficiency of theentire landing gear structure increases by 2%.