The Influences of Unbalance Mass, Mesh Density, and Bearing Clearance on Unbalance Response: Measurements and Analysis on a Rigid Rotor Supported by Hybrid Bump-Metal Mesh Foil Bearings

Hybrid bump-metal mesh foil bearings (HB-MFBs) are novel gas foil bearings (GFBs) that comprise foil strips and metal mesh blocks in bearing substructure. HB-MFBs have several advantages over previous GFBs, such as high structural damping, more precise size, dimensional stability, and highly efficient cooling management. This study designed and manufactured HB-MFBs and bump-type foil bearings (BFBs) with identical diameters and bearing clearances to compare their rotordynamic performance in a test rig with a rigid rotor supported by two GFBs and driven by an impulse turbine. The rotordynamic performance of the bearings in terms of mesh density, unbalance mass, and bearing clearance were measured and discussed by comparing the experimental results of the two types of test bearings. Experimental results show that the HB-MFBs can efficiently suppress the motion amplitude of subsynchronous vibrations of a rotor-bearing system at high rotational speed, although the added unbalance mass and bearing clearance vary in a large region.