Load carrying performance of the 2nd and 3rd generation journal bump foil bearings including two dimensional stiffness variations

Abstract

Journal bump foil bearing (JBFB) is the key component in high-speed turbomachinery. In this paper, load carrying performance of the 2nd and 3rd generation JBFBs with axial and circumferential stiffness variations are investigated applying a curve shell model. A nonlinear algorithm is employed to impose contact/separate and stick/slide constraints to foil structures. An effective inverse method is proposed to design the circumferential variations of bump radii, obtaining evidently wider area (over 110°) where higher film pressure distributes. Reduced stiffness of edge bump strips increases bearing load capacity and frictional energy dissipation particularly for the misaligned rotor. Results indicate the 3rd generation JBFB can achieve over 60% load capacity improvement compared to the 1st generation bearing with uniform bump structure.