Analysis of misalignment characteristics for textured foil journal bearing based on multigrid method

Surface texturing is an excellent solution to the load capacity deficiency of foil journal bearings. However, it will also introduce significant discretization efforts. This paper explored the possibility of searching the static balance locus of textured foil journal bearing using the multigrid method to ensure design efficiency. The modified Reynolds equation characterized the ultra-thin gas film behavior inside bump-type foil bearing, and two foil models were adopted simultaneously to obtain the foil's structural deflection. The predicted load capacity agreed well with the experimental data. The results indicate that multigrid can accelerate the solution process of the compressible pressure governing equation, and the speed can be increased up to 70% when the nonlinear discretization scheme is adopted. It is recommended that textures are located in the pressure-rising region along the shaft's rotating direction and that the axial direction is fully textured to improve load capacity. Moreover, the above texture distribution scheme can increase the tolerable maximum misalignment angle by 11.8% and enhance the stability of rotors operated in light-load and high-speed cases.