Numerical Analysis On Lubrication Flow Filed Of High-Speed Railway Vehicle Driving Gearbox

High-speed driving gearbox is one of the key components of the power bogie. With the improvement of train speed, the change of the flow field becomes more and more complicated. The lubrication oil distribution, velocity field, pressure field and turbulent intensity have a significant influence on the lubrication effect and functioning reliability of gearbox. In this paper, taking the high-speed driving gearbox as the research object, the distribution of the flow field was analyzed by numerical simulation method. Researched the influence of gear velocity, oil height and oil viscosity to the flow field of gearbox, providing theoretical guidance for the design of the gearbox lubrication.In this paper, taking the 300km/h high-speed train driving gearbox as the research object, established a two-dimensional flow field numerical simulation gearbox model. Gearbox internal flow field was complex. Selected the RNG k-ε turbulence model to simulate the gear box turbulent motion. Air was a compressible gas and would be compressed and expanded during gear transmission process. Based on the compressible fluid equations, analyzed the effect of air. Simulated air vent by setting the constant pressure based on the outlet boundary conditions. Selected the VOF two-phase flow model to simulate gas-liquid two-phase flow in the gearbox. Based on FLUENT moving grid technology, simulated the gears churning process.The results showed as follows:The lubrication oil was agitated constantly, gradually mixed with air and finally filled in the gearbox during the gear meshing transmission process. Fluid velocity was large around the end of the gears, relatively small close to the wall of the gearbox. The turbulent intensity was relatively large around the end of gears and where the gears mess. It generated obvious pressure differentials between the top and the bottom of the gearbox. Lubrication oil volume fraction on the gears end, pressure differential, average turbulence intensity changed over time in a state of slight fluctuations, but increased gradually and then got stable on the whole. Lubrication oil volume fraction decreased with gear rotation speed increasing. Average turbulent intensity went up with gear rotation speed rising. Lubrication oil volume fraction on the gears end increased with oil height promoting, while the increasing amplitude decreased. Oil height had little effect on the pressure field and the average turbulent intensity. Oil viscosity influenced the pressure field and the oil fraction slightly. Average turbulent intensity increased with oil viscosity rising, but the increasing rate decreased with time.