Research On Frictional Properties Of Megawatt's Wind Turbine Double-Row Tapered Roller Main Bearing

The energy problem is more and more serious, it's urgent to discover and apply renewable energy. As one kind of typical renewable energy power generation technology,wind power technology has vast potential for future development. One key part of wind turbines is main bearing, which influence wind turbine overall operating conditions by its property and reliability. The frictional performance is a key parameter to measure the main bearing's property, because it influences the inside temperature, abrasion and energy waste of the bearings, and then impact the overall performance of wind turbines. Previous studies of main bearing's frictional performance mainly used test methods or traditional bearing theories, which have many disadvantages, such as test methods need high costs and cannot reveal the relationships of parameters and bearing frictional performances, and the traditional bearing design theories not fully applicable to wind turbines main bearings, the analysis results have large errors. So that to find a special analysis method aim at wind turbines main bearings has great theoretical and practical significance. Focusing on the above problems, the tribology of main bearing is investigated in this dissertation, and the friction analysis method of main bearing is established. Based on the results of theoretical verification, factorial analysis of main bearing's friction is studied by the established analysis method, and then, aim at the specific loads and clearance cases of mainbearing, the examples analysis of main bearing's frictional performance is discussed. The main research work is as follows: (1) The friction torque caused by roller-raceway and roller-rib contact is mainly considered, and a friction torque theoretical analysis model of main bearing is established.The details of roller-raceway friction torque analysis model establishment mainly include solution of load distribution inside the main bearing, calculation model establishment of roller profile loads, lubrication analysis of roller slices based on EHL theory and solution of roller slices'friction torque, etc. The process of roller-rib friction torque analysis model establishment mainly includes contact conditions analysis of roller-rib, lubrication analysis of roller-rib contact based on point contact EHL theory and friction torque analysis of roller-rib contact based on the EHL analysis results. (2) After verifying the theoretical analysis model of main bearing friction torque,parametric analysis of parameters which influence main bearing friction torque is discussed based on theoretical model. The effect of main bearing's revolving speed,structure parameters and lubrication parameters to friction torque is emphatically analyzed.The analysis results provide a theoretical basis for main bearings'structural design and type selection from the viewpoint of tribology.(3) Examples analysis of main bearing friction torque is discussed. In the cases of a certain-type megawatt wind turbine main bearing's structure, the friction torques under different loads cases and clearance cases are analyzed. The analysis results provide a reference for main bearing's application and type selection from the practical viewpoint.