Investigation on the rotordynamic performance of hybrid bump-metal mesh foil bearings rotor system

Abstract The rotordynamic performance of a new designed gas foil bearing, hybrid bump-metal mesh foil bearing (HB-MFB), was investigated in this study. The elastic substructure of the HB-MFB was comprised by the foil strips and metal mesh blocks, which is different from the traditional bump-type gas foil bearing. The metal mesh material was introduced to improve the damping of the bearing, thus improving the stability of the rotor system. The new designed HB-MFB was manufactured and tested on a rotordynamic test rig in this study. The rotor responses were measured and analyzed under different operating conditions and bearing parameters. A theoretical model of the HB-MFB rotor system was built and demonstrated by the experiment results. The performance of HB-MFB was compared with traditional bump-type gas foil bearings. The effect of bearing parameters and operating conditions, like imbalance, mesh density, bearing load, and bearing clearance, on the rotordynamic performance of HB-MFB rotor system was studied experimentally and analyzed theoretically. The experiment results demonstrated that introducing metal mesh can suppress the subsynchronous vibration significantly, which means the stability can be improved. The critical speed changes slightly, while the synchronous amplitude increases as the imbalance increases in the whole operating speed range. The rotor responses under different static loads showed the stability was improved as the static load increases because of the improvement of the natural frequency and the threshold speed of instability. The rotordynamic performance of HB-MFB rotor system is sensitive with some of the bearing parameters, like mesh density and bearing clearance.