Investigation on Steady-State Thermal Performance of Gear Box Based on Thermal-Fluid-Solid Coupling

In order to accurately predict the temperature distribution of the gearbox of the rail transit transmission system, a mixed timescale coupling method based on computational fluid dynamics (CFD) was adopted to simulate the gearbox. The internal flow field and temperature field of the gearbox were simultaneously simulated, and the real-time two-way coupling between the flow field and temperature field was realized through data transmission. Finally, based on the calculation results of the internal temperature field, the temperature distribution of the gearbox was obtained by using the finite element method. In addition, the effects of rotational speed, immersion depth, injection lubrication, and other factors on the steady-state thermal performance of the gearbox were analyzed. The results show that the numerical model has a good performance in temperature prediction. Moreover, the maximum relative error between the simulation results and the experimental values is 7.4%. With the increase of rotational speed, the temperature of gear box rises accordingly. With the increase of oil immersion depth, except the fact that the bottom temperature of the lower box gradually increases, the temperature of other areas decreases. At the same speed, the maximum temperature of the box under oil injection lubrication can be reduced by up to 14% compared with splash lubrication. In addition, the rotational speed increases, the cooling effect becomes more apparent.