The Design Of Test Rig And Experimental Research For High-speed Gas Bearings

Gas foil bearing(GFB) use ambient air or process gas as lubricants; hence, they are considered good substitutes for conventional oil bearings or rolling element bearings in systems that operate at elevated temperatures and high speeds. Oil-free microturbomachinery supported by the GFB is compact and efficient because it has few parts, high-speed, and high operation temperature. With the developments achieved in the past several decades, GFB are becoming more and more mature in theory research and various bearing structure also have been proposed. This article combine the design of a type of air foil bearing—Hybrid bump-metal mesh foil bearing(HB-MFB), which use bump and metal mesh blocks as elastic supporting structure. Experimental studies were conducted on static and dynamic characteristic of HB-MFBs based on test rigs. The main research contents of the dissertation are as follows:The process of designing and manufacturing for HB-MFBs which use bump and metal mesh blocks as elastic supporting structure are discussed in detail. In the article, some key process are concluded, which include the process of bump designs, metal meshs arrangement in bearing housing and heat treatment technology.Based on the experiment scheme, HB-MFB and bump foil bearing(BFB) are tested for estimated their static and dynamic characteristic under the same load condition. The results show that the static structural stiffness of HB-MFB and BFB display strong nonlinear characteristics and form a hysteresis loop. Note that compare to BFB, the HB-MFB have larger hysteresis loop and exhibits better damping characteristics. With the increase in excitation frequency, all test bearings show an obvious increase in structural stiffness but a significant decline in equivalent viscous damping.A high-speed test rig using NI data acquisition system for GFB was designed and built, and the key components of test rig are intensive considered to ensure the good performance. To improve the performance of test rig, shaft laser alignment and dynamic balance instrument are used. Different test systems are conducted to satisfy different experiments.Push-pull experiment and impact load test are conducted based on the high-speed test rig to estimate the characteristics of HB-MFB. With increasing rotational speed, HB-MFBs exhibit an increase in the stiffness that attribute to the rise of gas film stiffness but an obvious decline in equivalent viscous damping. The results of impact load tests show that the stiffness rises as the increase of excitation frequency while the equivalent viscous damping exhibits a decrease independent of rotating speed.