A new boundary condition for the interconnected boundary of air-lubricated groove journal and thrust bearings

Abstract

When journal and thrust bearings have a common boundary, a conventional boundary condition that assumes that the boundary pressure is equal to atmospheric pressure is no longer valid. Instead., a new boundary condition for the interconnected boundary that the journal. and thrust bearings hold in common is required. In this article, a duct model satisfying mass conservation at the interconnected boundary is developed and a new boundary condition for the interconnected boundary is derived front the duct model. Using this derived boundary condition, the pressure distribution at the interconnected boundary and the mass flow rate in the circumferential direction of the interconnecting part are obtained with varying the volume of the interconnecting part. The obtained pressure of the interconnected boundary is much larger than the atmospheric pressure and the pressure on the whole bearing surface also increases compared with that of a simple thrust bearing, which does not have the interconnected boundary. Consequently, it is shown that the interconnected thrust bearing generally has a greater load-carrying capacity than the simple thrust bearing.