Experimental and theoretical investigation of rotordynamic characteristics of a rigid rotor supported by an active bump-type foil bearing

Abstract

This study aims to investigate the rotordynamic characteristics of a rigid rotor supported by an active bump-type foil bearing (ABFB) with real-time controllable mechanical preload. ABFB is composed of a traditional bump-type foil bearing with controlling substructures that consist of flexure hinges, lever amplifiers and piezoelectric stack actuators (PZTs). The structure realises the adjustment of bearing's mechanical preloads by actively controlling the DC voltage on the PZTs (U). Experimental investigations based on rotordynamic test rig are performed to measure the effects of ABFB on rotordynamic responses of rotor-ABFB system. Combined with the dynamics of the active control structures and modified link-spring model, linear and nonlinear mechanical models of the rotor-ABFB system are established, and the rotordynamic responses of the rotor are predicted. Both the experimental and theoretical results verify the possibility of building active rotor-gas foil bearing systems. Moreover, the effects of rotor unbalance on the rotordynamic responses of the rotor-ABFB system are investigated.