Thermal Behavior Analysis Of Split-torque Transmission Shaft System For A Certain Helicopter Main Reducer

Abstract:The helicopter main reducer is always under conditions of heavy load and high speed, and because of small size, compact structure and poor heat dissipation, all these could lead to large temperature rise for transmission system. High temperature can cause scoring failure of gear and bearing, and high temperature rise could cause gear and bearing excessive thermal deformation which eliminates the transmission gap and badly affects the working reliability and the lifetime of the transmission system. Therefore, it is of great significance to analyze the temperature distribution of gear, bearing and transmission shaft system.Firstly, the friction heat flux analysis of spur gear was studied on the basis of load sharing, heat sharing and different friction coefficient on engagement position, and heat transfer coefficients for different gear faces were calculated according to empirical formulas. The parameterized model of gear tooth was built up on the basis of APDL in ANSYS, and the steady temperature field of gear tooth was obtained by exerting loads to different gear faces. In order to verify the feasibility of simulation method for the steady temperature field of spur gear, the temperatures of gear contact surface under different conditions of torque, speed and oil input temperature were measured by thermal infrared imager. The simulation results were compared to the test results, and the feasibility of the finite element analysis method was verified.Secondly, in view of the load and lubrication characters of split-torque transmission, the steady temperature field of split-torque spur gear for a certain helicopter main reducer was obtained by steady thermal analysis, and the effects of torque, speed and oil input temperature on the steady temperature field of gear were analyzed. By taking the steady thermal analysis results as an initial condition, the transient temperature field of gear was analyzed, and the finite element simulation results were also compared to Blok flash temperature formula results.Finally, thermal loads of cylindrical roller bearing without inner ring and split-torque transmission shaft system were calculated on the basis of load sharing coefficient, and the steady temperature field of cylindrical roller bearing without inner ring and split-torque transmission shaft system were obtained by steady thermal analysis. Different effects of load sharing coefficients on the steady temperature field of cylindrical roller bearing without inner ring and split-torque transmission shaft system were compared.