Numerical Study Of Temperature Field Of High Speed Train Gearbox Based On Heat-Fluid Coupling

Gear transmission is one of the core components of high-speed train power bogie.With the continuous improvement of train speed and the increase of operating mileage,the temperature in the gearbox is becoming more and more complex,which will have a negative impact on the lubrication and sealing of gear transmission.Therefore,it is necessary to carry out further study of the temperature field in the gearbox.When the train runs at high speed,various power losses generated during the gear transmission process will eventually be transmitted outward in the form of thermal energy,making the temperature of the transmission system continuously increase.Lubricating oil is an important heat transfer medium in the gearbox,and its viscosity will change with the change of temperature.The change of viscosity may lead to gear bonding failure,bearing burn and gear transmission efficiency reduction and so on.Therefore,the study of the temperature field in the gearbox will provide positive and beneficial guidance for the lubrication mode of gear transmission and the design of cooling system,and will help to shorten the design cycle and reduce the design cost.In this paper,the gear transmission of high-speed train is taken as the research object.Based on the theories of fluid dynamics and heat transfer,the theoretical calculation is combined with the finite element simulation analysis.The temperature simulation analysis model of gear transmission device is established by using Pumplinx software,The magnitude and distribution of the temperature are systematically analyzed,and the effects of gear speed and oil immersion depth on temperature are compared and analyzed.The main research contents of this paper are as follows:1)The heat generation and transfer mode of gear transmission are analyzed.The convective heat transfer coefficient of the inner surface and gear end face of the gearbox under the condition of mixed flow of oil and gas,and the convective heat transfer coefficient of the outer surface of the gearbox with external air heat transfer.The convective heat transfer coefficients of the inner surface and the end face of the gearbox under the mixed flow of oil and gas are calculated,and the convective heat transfer coefficient of the outer surface of the gearbox with external air heat transfer are also calculated.2)The reasonable calculation methods are selected to calculate the power loss in the gearbox under different rotational speed and different temperature conditions,and the quantitative analyses of the calculation results are carried out.The results show that the power loss of sliding friction is negatively correlated with rotational speed and positively correlated with temperature.Rolling friction power loss,churning power loss,the windage power loss and bearing friction loss are positively correlated with rotating speed and negatively correlated with temperature.3)The variation function between viscosity and temperature of lubricating oil is determined,the approximate functions of various power losses varying with temperature are fitted,and the thermal load and initialization boundary conditions are set.The finite element numerical analysis model of gearbox temperature field based on heat flow coupling is established.And the variation of temperature and pressure under different rotational speed and oil immersion depth is calculated and analyzed.The analysis results show that the temperature in the gearbox is positively correlated with the rotational speed and the depth of oil immersion,and the change of pressure is positively correlated with the rotational speed,and fluctuates with the change of the depth of immersion.The pressure value is positively correlated with the rotational speed,and fluctuates with the depth of oil immersion.