Theoretical model construction and static performance analysis of multi-leaf journal foil bearings

Abstract

Abstract Multi-leaf journal foil bearing (MLJFB) structures are complex, making performance prediction challenging, and the accurate prediction of gas film thickness and pressure distributions is crucial. In this study, COMSOL finite-element software was used to establish an initial foil assembly and structural deformation simulation model for an MLJFB with bump foils. Using MATLAB, a compressible gas lubrication model was established and solved using the finite volume method (FVM). Real-time data transfer between COMSOL and MATLAB enabled a fully coupled fluid-structure interaction simulation. This model meticulously accounts for the pre-tension force in the multi-leaf bearing assembly, contact friction between adjacent foils, and the interaction between the top foil and gas film pressure. The effects of journal movement distance, direction, and top foil overlapping ratio on the bearing capacity as well as the effects of different external load directions on the journal equilibrium position were analyzed based on this model. The results indicate that increasing the top foil overlapping ratio enhances the bearing capacity of the MLJFB. Furthermore, compared to the direction of the top foil overlap position, external loads applied in the direction of the top foil midpoint are more beneficial for bearing operational stability.