Simulation of air foil bearings for use in turbo compressor applications

In recent years, the development of more efficient internal combustion engines (ICEs) has accelerated due to government legislation and social environmental outlook. Correct air management can improve the power density and efficiency of ICEs, increasing performance and lowering environmental impact. The use of air foil bearings (AFBs) in systems such as turbochargers can increase overall performance and efficiency. Additionally, AFBs are oil free, therefore are suitable for use in turbo compressors for hydrogen fuel cell applications, as the problem of membrane poisoning which could be experienced when using oil bearings can be avoided.

A novel explicit co-simulation methodology for analyzing the dynamic performance of a turbocharger using AFBs is presented. Using bearing maps defining colinear stiffness and damping, an adaptable tool is created through a mathematical bearing model explicitly coupled with a flexible multibody dynamic system. This full system level model considers flexibility of the bodies in the system as well as a Coulomb damping mechanism provided by the sub-foil structure in the AFBs. The resonance of the system was observed around 70krpm with some non-linear and sub synchronous vibrations also being experienced. Although computationally intensive, significantly more modes of vibration were detected when compared to rigid body analysis.