基于落震试验的油—气式起落架气体压缩多变指数变化规律研究

On the Gas Compression Polytropic Index Variation of Oil-Gas Type Landing Gear based on Drop Test

气体压缩多变指数是油气式起落架缓冲性能计算中的重要参数。通过对某型飞机油气式起落架落震试验中气腔压力数据的监测,对不同落震投放高度下气体压缩多变指数进行识别。利用最小二乘法,对多变指数变化曲线进行三次拟合,得出活塞杆压缩过程中气体多变指数的变化规律。本文建立了某型飞机起落架落震试验仿真分析模型,将拟合曲线引入仿真计算模型,对比了定常多变指数计算模型和非定常多变指数计算模型仿真结果。相对于定常多变指数模型,非定常多变指数计算模型仿真结果和试验对比误差小于定常多变指数计算模型,提高了仿真分析精度。

Gas compression polytropic index is an important parameter in cushioning performance calculation of gas-oil type landing gear.In drop test,based on monitoring the pressure data in gas chamber of an oil-gas landing gear,gas compression polytropic index is identified for different drop heights.Using the least squares method,the polytropic index curve is fitted three times,the variation of polytropic index during gear piston compression is obtained.A numerical model for landing gear drop test is established.The fitted curve is used in the model,and the calculation result obtained from the model using steady polytropic index is compared with the result from the model using unsteady polytropic index.Comparison shows that the calculation by using unsteady polytropic index is better than that obtained by using steady polytropic index.So,the precision of simulation is improved.