With the rapid development of high-speed, oil-free turbomachinery, more and more attention is concentrated on compliant aerodynamic foil bearings. However, the common corrugated bump foil forming the compliant structure is so complicated that manufacturing it is time-consuming and troublesome. In this article, a simple type of aerodynamic foil thrust gas bearing with an elastic hemispherical convex dot support configuration is first proposed. Then experimental investigations on stability and its load capacity characteristic for this foil thrust bearing were conducted on a multi-functional thrust bearing test rig. The preliminary measurement and analysis are presented through the wave and spectrum of axial displacement response in the time and frequency domain. It is demonstrated that the proposed bearing can operate well and has good stability in tests, and experimental results show that the axial load can reach 25 N when the rotational speed is about 114 200 r/min.

The miniature high-speed gas-bearing turbomachinery is one of the research focuses in the fields of energy and cryogenic engineering in recent years. In this article, a new miniature static gas-bearing expansion turbine with a shaft diameter of 6 mm, turbine impeller diameter of 9 mm, and designed rotational speed of 300 000 r/min was developed. The developed prototype of this miniature expansion turbine is comprehensively introduced and the structure characteristics are presented. Then the preliminary mechanical and thermodynamic performances for the developed prototype are experimentally measured. Research results show that this developed expansion turbine has some noticeable features, such as stable operation with small vibration. It can reach 15 per cent over-speed and provide a quick temperature drop. Experimental verification demonstrates that both mechanical and thermodynamic performances agree with expected requirements. Hence, a strong base has been established in China to further develop miniature high-speed gas-bearing expansion turbines.