The performance of Generation II journal gas foil bearing with misalignment.

Purpose: The normal operation of a rotor system is generally vulnerable to misalignment between gas foil bearing (GFB) and rotor. However, most theoretical and experimental researches about the characteristics of GFBs have ignored this phenomenon. Therefore, the main purpose of this paper is to evaluate the static and dynamic performance of GFBs considering misalignment. Design/methodology/approach: The shaft is allowed to misalign in two directions. Then the variations of bearing load, friction force, restoring moment, stiffness and damping coefficients are thoroughly explored. The hydrodynamic pressure on the gas film is modeled with compressible Reynolds equation, and the deformation of the flexible bearing is calculated with finite element method. Small perturbation method is used to obtain the displacement and moment dynamic coefficients. Findings: The film thickness and pressure distribution distort when misalignments appear. The inclination of GFBs can enhance the restoring moment to withstand the imposed misalignment. Furthermore, the simulation phenomenon demonstrates the misalignment around load direction should be avoided as much as possible, while a small value misalignment around another direction is allowed. Originality/value: The value of this paper is the exploration of the influence of misalignments on the static and dynamic performance of the Generation II journal GFB. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-10-2019-0418/ [ABSTRACT FROM AUTHOR]