Design Of Hybrid Journal Bearing And Oil Film Bearing Capability Analysis

Along with the modern industry development, the rotating machinery needs to be faster and of more power, thus requires bearings of better performance. The hydro-hybrid bearing, which combines the advantages of both the hydrodynamic bearing and hydrostatic bearing, emerges in response to the needs. It has higher bearing capacity, rigidity and oil-film damping, therefore is adaptable to super-high speed grinder. Up to now, however, there’s neither a complete set of design approaches to structural or mechanism dimension design, nor unified design criteria or technical specifications. The immature design technology limits its application. On the other hand, considering the hydro-hybrid bearing uses hydraulic oil, the film load performance of which descends when operating under high speed working condition as the temperature rises, which in turn influences the machining accuracy.After investigating into the newest research the basic theory of hydrodynamic bearing, hydrostatic bearing and hydro-hybrid bearing, this article builds up the structural parameter design method of hydro-hybrid bearing. Resorting to computational fluid dynamics (CFD), the hydro-hybrid bearing was simulated with computer calculation. First of all, the hydro-hybrid bearing of the super-high speed grinding test-bed principle axis in Northeastern University was chosen as the research object, which was later modeled, meshed and set boundary condition with GAMBIT. Then the model was imported to FLUENT and set parameters. In the end, the pressure field and temperature field were obtained after iterative computation.The pressure distribution nephogram shows that there’s a clear low pressure section near oil chamber when the bearing is rotating speedily, meanwhile the high pressure section locates to the outer fringe of the chamber. As the rotating speed increases, the pressure and oil film bearing capability increases, too. When the speed increases to a certain value, the oil flow reverses to the inlet and the pressure increase will be constrained, thus makes the bearing capacity increase slowly. The temperature distribution nephogram shows that as the rotating speed increases, the temperature of the oil film in the bearing also increases; nevertheless, the temperature gradient decreases and the homogenization effect is distinct. Especially, when the rotating speed reaches10,000r/min, the temperature filed distribution of the oil film becomes fairly uniform.As per research in this article, the3D numerical simulation method of hydro-hybrid bearing with CFD technology. The calculation result reflects effectively the flow state in the bearing, it also provides theoretical basis for the hydro-hybrid bearing testing method, as well as for the high speed hydro-hybrid bearing design and development.