基于流固耦合的分动器齿轮两相流动数值模拟与试验

针对分动器齿轮啮合传动中,润滑油运动过程缺乏研究和油压油速等相关参数不确定的问题,应用数值模拟与试验相结合的方法进行了详细的分析。建立分动器齿轮流场三维模型,基于流固耦合理论,应用Fluent UDF命令设定齿轮动网格运动,建立VOF两相流模型进行数值模拟,结果表明:0～0.5T(小齿轮以400 r/min速度旋转一周耗时为1T)时刻,从动大齿轮旋转带油对啮合区润滑起主要作用、速度流线在啮合区附近出现明显的漩涡现象、啮合齿面间压力值相对较大、两相流模型的改变对齿轮带油润滑效果有较大影响;应用高速摄影技术,对透明分动器壳体内流场流动情况进行观察试验,其油面波动与数值模拟结果作对比,最大误差为12.2%,误差较小,表明试验与数值模拟的分析结果相吻合。研究成果为下一步改善分动器齿轮润滑方面的工作提供参考。

Numerical simulation and test on two-phase flow inside shell of transfer case based on fluid-structure interaction

Abstract: In order to investigate the characteristics of air-oil two-phase turbulent flow inside the shell of transfer case, the research method to combine test and numerical simulation is proposed to take analysis. The fluid-structure interaction theory (FSI) is a science to research the interaction and influence between fluid and structure fields, and is applied to research single-direction influencing characteristic from gears rotation to air-oil field flow. The gears of the transfer case transfer power via meshing and rotating, their movement is imitated by dynamic mesh technology is fluent. Fluent UDF definition is used to define the parameters of dynamic mesh control. The fluid field inside the shell of the transfer case has two phases: air and oil. It starts to move and show its fluid characteristics in close relationship with the motion trail of gears. The air-oil fluid field belongs to a two-phase model. It is simulated by the VOF model is fluent. The interface of gas and liquid is defined by fluent UDF definition. High speed photography is the application of advanced photographic technology for high-speed motion characteristics of a clear picture. It is used to observe high-speed motion characteristics. With a transparent shell, the transfer case assembly is installed on the test bench for the observation test. The movement of air-oil fluid field has been observed after high speed photography.The results show that, during 0-0.5T moment, driven gear to rotate with oil plays a main role in the meshing zone lubrication; at 0.25T moment, gears start to mesh and rotate, oil fluid field wave; at 0.375T moment, the gear meshing area is filled with lubricating oil; at 0.5T moment, the continuous oil inflow meshing zone above, and cover the gear meshing area of tooth surface, achieve initial lubrication. The vortex phenomenon appears near the meshing zone in the velocity streamline. The speed near the wall is higher than the other zone. The velocity streamlines into and out of the meshing zone more effectively. After the pressure field stabilizes, the flow field pressure maximum value appeared in the gear meshing area; two phases of flow field in the shell are uniform, the middle of the fluid pressure is relatively small; negative pressure appears below the driven gear part. The numerical simulation results coincide with the test. The analysis results are true and valuable.