Wind Power Main Shaft Bearing Lubrication Characteristics Analysis And Optimization Design Based On Rheology

During the operation of wind turbine,the main shaft bearing is often in low speed,wide temperature,heavy load,vibration and high humidity environment,so it has extremely high requirements for lubrication performance.Whereas,the rheological characteristics of grease is the key index to evaluate the lubrication performance of wind power main shaft bearings.On the one hand,the rheological characteristics of grease directly affects the friction performance of bearings,which in turn affects the wear and heat distribution of bearings;on the other hand,the stability of flow state of grease in bearings is also affected by the rheological characteristics,which consequently affects the bearing capacity and lubrication performance of grease in bearings.Therefore,the research of rheological properties of grease is essential to optimize grease formulation,improve grease performance and reduce bearing wear problems.This research takes wind power main shaft bearings and its grease as the object of investigation.And firstly,the flow of grease in the bearing is simulated;secondly,the rheological behavior of the grease is experimented;finally,the lubrication characteristics of the bearing are optimized based on the above simulation and experiments.The following tasks and achievements were specifically accomplished in this paper:(1)The wind power main shaft bearing and its grease as the research object,the common tribological problems and lubrication failure of the bearing are discussed,and based on this,the wind power bearing lubricity pattern is explored.(2)For the wind power main shaft bearing greasing problem,based on fluid dynamics theory,a FEM model of the bearing is formulated and the fluid flow of the lubricant inside the bearing is modeled using FLUENT software.In the simulation,the influence of different factors on grease circulation is analyzed and the major factors affecting lubrication performance are identified,thus providing a theoretical basis for optimizing grease formulation and enhancing bearing life.(3)An experimental study of rheological behavior for wind power greases was carried out with a rheometer equipment.The influence of viscoelastic properties,flow behavior and viscosity-temperature properties of different greases on bearing lubrication at different temperatures was analyzed.At the same time,we investigate the rheological parameters of the grease,which provide an essential reference for optimizing the lubrication properties of bearings,and also provide a more detailed and scientific analysis of the lubrication of bearings in wind power main shafts.(4)The rheological model concept has been introduced and fitted to the rheological curves and parameters of grease,and thus the computational equations of shear stress of grease have been obtained.Meanwhile,the rheological parameters of grease obtained from rheological experiments were used to optimize the design of lubrication feature for wind power main shaft bearings.The minimum oil film thickness and the rated dynamic load of the bearing were optimized by genetic algorithm to establish the basis for further enhancement of the lubrication performance of the main shaft bearing.