Study On The Effects Of Surface Texture And Bubbly Oil On Performance Of Journal Bearings

Surface textured bearing has great application prospect. However, the conclusionsabout the effects of surface texture on the lubrication performance of journal bearing havealways been inconsistent and the wear of suface textured journal bearing has not been clear.In addition, the high-speed journal bearing will work under bubbly oil lubrication, but theconstitutive equation and lubrication model of bubbly oil are not unified, and theconclusions about the effect of bubble on the lubrication performance have beeninconsistent. In this paper, the effects of suface texture and bubbly oil on the performanceof journal bearing are studied. The main contents and conclusions are as follows:The lubrication model of surface textured journal bearing based on the JFO boundaryconditions is constructed and the generalized Reynolds equation is solved numerically. Theresults show that the performance of part textured journal bearing is better than theperformance of full textured bearing, and with the increases in textured depth and radius,the attitude angle and the friction force decrease, while the load carrying capacity isreduced. The attitude angle, leak flow and friction force of journal bearing with rectangularsection textures are the lowest.The deterministic mixed lubrication model of surface textured journal bearing isestablished, and the predict method of wear is proposed. The wear processes under variousloads and the influence of surface texture on the wear performance are studied numerically.The results show that the surface texture on the journal bearing will enlarge the range ofwear.The rheological test system of bubbly oil is set up. The influences of shear rate,temperature and bubble content on the rheological performance of bubbly oil are studied. Anovel viscosity model and constitutive equation are developed, which can be applied to thesituations with various shear rates and temperatures. The results show that as the bubblecontent increases, the viscosity increases under lower shear rate, while the viscositydecreases under higher shear rate.Based on the constitutive equation of bubbly oil, the bubbly lubrication model ofjournal bearings is developed, in which cavitation algorithm is also applied. The effects ofair volume fraction and shear rate on bearing performance are analyzed. The results showthat as volume fraction increases, maximum pressure, load capacity, friction force and leak flow increase slightly at lower shear rates, decline obviously at higher shear rates, butincrease to a peak and then decrease at intermediate shear rates.