Analysis Of Internal Flow Field Of Locomotive Gear Box

Gear reducer is an important part of vehicle transmission, its performance directly affects the vehicle’s driving state. With the rapid development of the railway industry, the requirement of the railway train on gear performance is also constantly improving. With train in the normal speed, the distribution of lubricating oil changes violently, and the change of internal pressure and temperature will be very complex, which directly affects the lubrication of the gear box and the sealing performance. This paper takes a train gear reducer as the research object, analyzed the variation regularity of the internal flow field, and provides a theoretical reference for the gear lubrication and sealing.First, this paper establishes the gear box of a two-dimensional model, then uses the pretreatment software Gambit to generate mesh for the gear box model and define the type of boundary condition. Basing on the incompressible fluid control equations and the turbulence model, using the N-S equation, the turbulent flow equations and PISO algorithm, the internal flow field of the gear box are studied by numerical simulation. Using the dynamic grid technology of CFD software package to realize the rotation of gears, and using the VOF method to monitor variation of the oil liquid in the box. This paper makes a comparative analysis of the flow field inside the gear box from the three aspects of lubricating oil viscosity, immersion depth and gear speed.The results show as follows:The maximum velocity occurs in the gear box gear meshing area; The gear box of the maximum pressure occurs in the mesh area; Near the small gear will produces vortex which is opposite from its rotation direction, while the air is very smooth near the big gear; With the decrease of the viscosity of lubricating oil, lubricating oil is more likely to be stirred up; With increasing of the immersion depth, at the initial stage of gears rotating, more lubricating oil is stirred up into the gear mesh, but with the passage of time, the lubricating oil at gear box bottom can not be stirred up quickly and fully; When the immersion depth is 2h and 2.5h,there will be more oil and gas mixture inside the gear-box, which is more conducive to gear lubrication and cooling. Under normal operating conditions, with the increasing of speed, the lubricating oil will be stirred up faster, the pressure values of the three points are also increasing with the increasing of velocity, turbulence will be also more intense.