基于气液两相流数值模拟的起落架油气缓冲器阻尼特性研究

Study on the damping characteristics of a landing gear oleo-pneumatic shock absorber based on numerical simulation of the gas-liquid two-phase flow

为了研究起落架油气缓冲器的阻尼特性,利用CLSVOF方法捕捉气液两相界面,采用Peng-Robinson真实气体模型模拟气相(氮气)行为,对缓冲器内部油气两相流动进行了瞬态数值模拟,通过流场分析对缓冲器的阻尼特性进行了研究。数值仿真模拟了油液以射流形式从主油孔流出,并与氮气腔上壁面碰撞,出现了油气两相混合及油液附壁流动等复杂现象;在阻尼特性研究中,基于流场分析计算得到的油液阻尼力峰值小于定流量系数时的工程计算结果,且相比工程计算结果存在一定的迟滞性;大量油液阻尼能量损失的产生集中在缓冲器压缩过程。研究结果可以为起落架油气缓冲器结构设计与性能优化提供参考。

In order to study the damping characteristics of the landing gear hydro pneumatic bumper,the CLSVOF method was used to capture the gas-liquid interface,and the real gas model Peng-Robinson was used to model the gas phase(nitrogen)behavior.The transient oil-gas two-phase flow inside the shock absorber was simulated by numerical simulation,and the damping characteristics of shock absorber were studied through flow field analysis.The numerical simulation accurately describes that the oil flows out of the main orifice in the form of turbulent jet and collides with the upper wall of the nitrogen chamber,resulting in complex phenomena such as oil-gas two-phase mixing and wall-attached flow.In the study of damping characteristics,the peak value of oil damping force calculated on the basis of the flow field analysis is lower than the engineering results when the discharge coefficient values are fixed.Moreover,there is a certain hysteresis compared with the engineering results.Large amount of oil damping energy loss is concentrated in the shock absorber compression process.The research results can provide some reference for the structural design and performance optimization of landing gear oleo-pneumatic shock absorber.