Numerical Analysis Of Flow Filed And Labyrinth Seal For High-speed Train Gearbox

Gearbox performance directly affected the power, safety and reliability of the high-speed train unit. With the speed increasing, the gearbox internal flow filed becomes more derangement and the pressure fluctuation becomes more complex. This directly effects uniform distribution of the lubricating oil, and also causes the weakening or even failure of the sealing performance in the labyrinth sealing system. In order to reveal the distribution of the internal flow filed and the leakage mechanism of the sealing system, the high-speed train gearbox was selected and the gearbox internal flow filed distribution, the sealing performance of the axial and radial labyrinth sealing were simulated by the numerical tools, provided theoretical guidance for the design of the gearbox lubrication and sealing system.Based on the VOF two-phase method and the adaptable grid reconstruction technique, 3D-model of gearbox internal flow filed was established by Pumplinx software. The gearbox internal flow filed transient variation was analyzed. The effects of different gear speed, immersion depth, oil viscosity and gear thickness to the gearbox flow filed were studied. The results show that, the vortex phenomenon appears in the gear engagement area and the oil sump left zone. The engagement inlet zone has the positive pressure fluctuation and the outlet zone has the negative pressure fluctuation, and the outlet pressure fluctuation is stronger than the inlet zone. The pressure fluctuation is strong at the vent-hole zone. Gear speed, immersion depth, oil viscosity and gear thickness has little effect on flow filed. But with the increasing of the gear speed, immersion depth, oil viscosity and gear thickness, the greater fluctuate of gearbox internal pressure.2D-model of the straight-through gearbox axial labyrinth sealing with bilateral rectangular cavities was established by Fluent software. The axial labyrinth sealing mechanism was analyzed and the effects of different pressure ratio, rotor speed, rotor radius and the tooth geometric factors to the labyrinth sealing performance were studied. The results show that, the increasing of the pressure ratio and the tooth gap make the leakage loss increase. Rotor speed, rotor radius and tooth thickness has little effect on the sealing performance. The larger the cavity width, the better the labyrinth sealing performance, but the cavity depth has a complex effect on the sealing performance. Considering the cavity width and depth, the ratio of the cavity depth and width is recommended as 0.2.2D-model of the gearbox radial interlocking labyrinth sealing with conical tooth was established by Fluent software. The radial labyrinth sealing mechanism was analyzed and the effects of different pressure ratio, rotor speed, the tooth engagement depth ratio and tooth angle to the labyrinth sealing performance were studied. The results show that, the fluid high-speed thoroughfare is exist in radial labyrinth and the leakage loss is large when the tooth engagement depth ratio is 0.6. The best tooth engagement depth ratio is 0.1. The increasing of the pressure ratio makes the leakage loss increase. Rotor speed has little effect on the sealing performance. The leakage loss of the labyrinth sealing increases with the increasing of the tooth angle. So the sharp tooth is conducive to improving the sealing performance.