Research On Tribological Performance Of The Engine Journal Bearing With Dimple

Machining dimple on the surface of a journal bearing to improve its tribologicalperformance is a technique that has sprung up in the world. Researching on tribologicalperformance of a dimpled bearing can provide a new method for bearing design, to raiseperformance of the engine bearing and entire engine. Therefore, the research has certaintheoretical and practical value.Considering the limitness of Reynolds equation in researching dimple lubricationproblem, computational fluid dynamics (CFD) analysis of a dimpled journal bearingwas carried out in this paper based on Navier-Stokes equation. The effect of dimple onlubrication performance of the bearing was studied, and geometric sizes, layoutparameters and shape of dimple were optimized. Finally, the contact characteristic of adimpled bearing was studied. The main contents of the dissertation include thefollowing:①Lubrication performances of the dimpled journal bearing with differenteccentricities and different speeds were studied, The numerical result indicates that:Appropriate dimple can increase the maximum film pressure and load–carrying capacity,reduce friction coefficient of the bearing. Additional hydrodynamic effect is morenoticeable on the bearing at lower eccentricity ratios;②The effects of geometric sizes,layout parameters of dimple on the lubricationperformances of the bearing were researched. Analysis result demonstrates that：by theuse of increased width or length and decreased depth of dimple, the maximum filmpressure and load–carrying capacity of the bearing increase, while the frictioncoefficient of the bearing decreases. There is an optimal dimple density or covering areafor the maximum load–carrying capacity or minimum friction coefficient. The dimpleslocated in the region existing in the maximum hydrodynamic pressure have a bettereffect on lubrication performances of the bearing.③In two aspects of groove dimple and spot dimple, the effect of dimple shape onlubrication performances of a bearing was studied. The numeric result indicates thatlubrication performances of the bearing depend on dimple shape. Compared withrectangle and trapezoidal groove dimples, Hemispherical and triangle groove dimpleshave a better effect on improving lubrication performances of the bearing. Comparedwith rectangle and triangle spot dimples, Hemispherical and cylindrical spot dimples have a better role in increasing load–carrying capacity and reducing friction coefficientof the bearing.④Contact analysis of the dimpled bearing was carried out with different loadsand different friction coefficients in finite element analysis method, and the effect ofgeometric size, density and shape of the dimple on contact performances of the bearingwas discussed. The numeric result indicates that dimple can increase the maximumequivalent stress, maximum contact stress and maximum contact displacement of thebearing. The maximum equivalent stress, maximum contact stress and maximumcontact displacement increase occurs with increased width and density of the dimple.Inaddition, different shape dimples bringout changes in contact performances of thebearing.