Axial gas foil bearings as lubricant-free bearings for high-speed rotors - Experimental investigations and numerical prediction

作为研究项目的一部分，对气体箔式推力轴承（GFTBs）的动态特性进行了实验研究，以建立一个系统结构化的GFTBs实验数据库。该数据库用于进一步的科学研究，特别是用于开发新轴承类型的数值模拟和设计由气箔轴承支持的转子系统，例如燃料电池系统中的无油涡轮压缩机。为此，在申请人现有的结构分析试验台上，确定了不同坡道和结构几何形状的GFTB弹性结构的静动力性能。此外，在即将建立的参数识别试验台上，根据不同的工作参数对GFTB的刚度和阻尼特性以及承载能力进行了识别。此外，这些实验确定的轴承参数与申请人已经在各种期刊文章中发表的仿真模型的数值结果进行了比较和验证。在现有燃气箔滑动轴承转子动力试验台的基础上，建立了燃气箔滑动轴承转子动力试验台，分析了燃气箔滑动轴承及其改进对轴向和径向燃气箔滑动轴承支承转子系统非线性振动行为和稳定性的影响。从而可以通过实验确定不稳定起始速度（OSI）和次同步振动起始速度（OSSV），并与数值计算进行比较。

As part of the research project, experimental investigations of the dynamic behavior of Gas Foil Thrust Bearings (GFTBs) are carried out in order to create a systematically structured experimental database on GFTBs. This database is used for further scientific investigations, especially in numerical simulation for the development of new bearing types and the design of rotor systems supported by gas foil bearings, e.g. oil-free turbo compressors in fuel cell systems. For this purpose, the static and dynamic behavior of the elastic structure of the GFTB with different ramp and structure geometries is determined on the existing structural analysis test rig of the applicant. Furthermore, the stiffness and damping properties as well as the load carrying capacity of the GFTB are identified depending on various operating parameters on a parameter identification test bench to be set up. In addition, these experimentally determined bearing parameters are compared and validated with the numerical results of the simulation models already published by the applicant in various journal articles. Furthermore, based on the experience with the existing rotor dynamic test stand with Gas Foil Journal Bearings (GFJBs), a rotor dynamic GFTB test stand will be put into operation in order to analyze the influence of GFTBs and their modifications on the non-linear vibration behavior and the stability of rotor systems supported by axial and radial gas foil bearings. Thereby, the Onset Speed of Instability (OSI) and Onset Speed of Sub synchronous Vibration (OSSV) can be determined experimentally and compared with the numerical calculations.