Study On Temperature Field Of Spiral Bevel Gear Transmission System Of A Helicopter In Case Of Loss Of Lubrication

In the modern war, the armed helicopter plays an important role in the militarymission, such as air-to-ground attacking, firing support, dog fight, reconnaissance,escort and so on. Its great power and irreplaceable role has been recognized by thepeople of the world. Nevertheless, today as air defense is increasing a lot, the armedhelicopter not only need to execute assignment, but also face a battlefield environmentwhich is detected and attacked by much azimuth and kinds, therefore the armedhelicopter’s viability of battle field is seriously threatened. In the battle, when thetransmission system of armed helicopter is shot and leaks oil, it will cause an extremecondition such as loss of lubrication. In this situation, the working time of transmissionsystem decides the armed helicopter’s survival ability and crews’ security. Therefore,with the requirement of the survival ability of the armed helicopter’s transmissionsystem, it’s very necessary to launch a research about the temperature field ofhelicopter’ transmission system in the condition of lossing lubrication, and it’s animportant way to improve the transmission performance and resisting failure property ofthe transmission system. The research results may help us to design and research thesurvival ability of our country’s armed helicopter, and it also can be extended to vehicles,ships, aircraft and other civil or military mechanized equipment. It has great applicationand economic value.In this paper, taking the spiral bevel gear transmission system of a helicopter tailreducer as research object, based on the theories of the gear engagement principle,tribology theory, heat transfer theory and thermal network method, etc, the heatgenerating mechanism, heat transfer process and temperature field distribution of thespiral bevel gear transmission system were analyzed and studied. The main contents andachievements are listed as follows:1、 Thermal network nodes were classified and described, and the divisionprinciples of nodes were established. Taking the spiral bevel gear transmission systemof a helicopter tail reducer as research object, distributing the nodes according to thecorrelation of heat transfer among parts, the model of thermal network was built and thebalance equations of nodes temperature were established.2、Simplifying spiral bevel gear to spur gear, considering the impact of gear contactratio and time-variant factors including meshpoint relative sliding velocity, normal load,friction coefficient, etc, then the computing model of friction power loss for spiral bevelgear was established.Besides, considering the impact of the variation of physicalparameters of hot air, the computing model of friction power loss for rolling bearing was established in different lubrication.3、The computing model of thermal resistance and convective heat-transfercoefficient of spiral bevel gear transmission system were established in the normallubrication and loss of lubrication. In the loss of lubrication condition, because thephysical parameters of hot air vary with temperature, the convective heat-transfercoefficients between the transmission system and hot air have the feature oftime-varying.4、Taking the spiral bevel gear transmission system of a helicopter tail reducer asresearch object, the calculation model of the temperature field simulation in the normallubrication was established by Simulink. Based on the model, the temperature curvevarying with time was calculated in the normal lubrication, and the steady-statetemperature field distribution was extracted as the initial conditions of the prediction ofthe transient temperature field in the case of loss of lubrication.5、Taking the spiral bevel gear transmission system of a helicopter tail reducer asresearch object, the calculation model of the temperature field simulation in thecondition of lossing lubrication was established by Simulink. Based on the model, withthe steady-state temperature field as the initial condition, the transient temperature fieldof the transmission system was calculated in the condition of loss of lubrication, and thenodes temperature varying with time were analyzed.6、This is the first time the Simulink was used to simulate and calculate thetemperature field of spiral bevel gear transmission system. The method can be used tonot only calculate the equilibrium value of temperature field (the steady-statetemperature field), but also forecast the temperature curve varying with time (thetransient temperature field). Therefore, it provides a new idea for analyzing andstudying the temperature field of gear transmission system.