Steady-state Thermal Analysis Of Gear Transmission System For Supercritical/Ultra-supercritical Thermal Power Units

Fluid coupling transmission is a composite transmission composed of high-speed heavy gears, hydraulic couplings and hydraulic controlling systems, and its regulating range is twenty-five percent to ninety-seven percent. It's mainly used in the field of changing speed. Then the input and output rotate speed can be changed steplessly in the case of constant motor speed. In addition, it is respected by low power consumption, long life, high control precision, high reliability, small shock and vibration, energy-saving effect and low cost of operation and maintenance. In this paper, in the condition of supercritical/ultra-supercritical thermal power unit, heat balance is analyzed for the gear part of fluid coupling transmission, and the results are used to guide the design of transmission structural. The main works are as follows:1.Based on the basic principles of heat transfer, the heating mechanism and heat transfer form of the fluid coupling transmission are analyzed, reasonable assumptions and simplifies are made, then the gear part of the transmission is compared to the normal gear transmission, in order to find the method to analyze its heat balance.2.Based on the principle of thermal network method, temperature nodes are pre-setted on the gear pair of the transmission, the heat source models, convection models and thermal resistant models are respectively established, equation sets are given based on the thermal networks. Then the thermal resistance matrix, temperature nodal vector and heat source vector are obtained, and the node solution is found by solving.3.Based on the basic theory of finite element method, heat balance equations are derived for the gear body in steady-state conditions, the single-tooth helical gear solid model is established by reasonable assumptions of the temperature field, then it is analyzed with finite element method, and ultimately the temperature field distribution of a single model is got.4.The results of the above two methods are analyzed and compared, and the reasons for the differences between the results are obtained. A series of useful conclusions are used to support the structure design of the transmission. 5.The influence of module, tooth width, helix angle, and initial oil temperature on the steady-state temperature field is analyzed, in order to provide supports for the structural design.6.The heat balance analysis of high-speed heavy gears and steady-state temperature field analysis of gear body are prospected.