The dynamics of the laboratory rotor founded on the gas foil bearings—numerical analysis

Abstract

The paper presents a fragment of the investigations on the gas foil bearings modeling, which were made out in the Institute of Fluid Flow Machinery (IMP PAN). The calculations are carried out in the S-MESWIR system of computer codes, originally invented in the IMP PAN and with the use of commercial software. A two-bearings laboratory rotor of about 3.5 kg weight is proposed. It is modeled in the S-MESWIR system with the use of beam finite elements. It is dynamically forced with the unbalance. The properties of the bearings are defined with the FE model of foil set. The air was assumed as a lubricating gas. For low speeds the gas layer may be not developed because the aerodynamic effects between the bearing journal and the top-foil are too weak. Thus the rotor is supported on the foils only. For higher values of rotational speed a gas film was fully developed and it takes part in the carrying of the load. The paper presents the example how the modification of the structural layer properties (especially stiffness) can change the dynamic characteristics of the rotating system.