Parametric Study of Bump Foil Gas Bearings for Industrial Applications

Gas bearings are an appealing technology for rotor support due to their inherent characteristic of oil-free operation. Elimination of lubricant brings also the possibility of designing the bearings for operation within the flow path of thermal machines and even using the process gas as working fluid for the bearing. Among several gas bearing technologies, foil bearings are the most common ones currently found in applications such as small compressors for aircraft pressurization, microturbines, and other small turbomachinery. Broad application of foil gas bearings to date is precluded due to their limited load capacity. Presently, scaling up of foil bearings requires expensive testing due to limitation of validated computational models of the fluid flow in the bearing coupled to the mechanical behavior of the metal foil and underlying corrugated structure. Recent work in this area shows that calibrated models are now available in the open literature and it is possible to predict more accurately the performance of the bearings at non-conventional sizes. The objective of this work is to present a study of the most relevant parameters of foil bearings affecting their static and dynamic performance and aimed at scaling them up for industrial applications currently not considered for them. The paper presents a calibration of the computational model to previous tests by independent researchers and discusses simple rules for scaling up the bearing components. Finally, the paper presents a feasibility study of application of foil gas bearings to a generic centrifugal compressor for industrial use.