Numerical and experimental study on air thrust foil bearing performance with improved structural model based on real-time taper inlet height

Abstract

<jats:title>Abstract</jats:title> <jats:p>Air thrust foil bearings are key bearings of micro turbo-machinery (such as micro gas turbines, turbo blowers, and air compressors). The bearing load capacity is affected by many factors, and the taper inlet height of bearing structure is closely related to the load capacity. In many previous literature the taper inlet height, as a constant value, was used to calculate film thickness distribution. However, the reality is that the foil will be squeezed by the pressure generated between runner disk and top foil, which makes taper inlet height change during iteration. Therefore, the actual bearing taper inlet height should be chosen properly instead of the constant taper inlet height when iterating. In this paper, an improved computational model of film thickness for adjusting the taper inlet height in real-time is proposed. The relationship between the maximum bearing load capacity and taper inlet height at different rotor speeds of two models is obtained through numerical simulation. It is found that the optimal taper inlet height of the new model is larger than that of the old model. Three types of bearings with different taper inlet height (20μm, 70μm, 114μm) had been tested and the maximum load capacity at different rotor speeds had been obtained. Finally, test data and the simulation results of the two models are compared. It is found that the simulation results of the two models are quite different when the taper inlet height is near the optimal taper inlet height, and the new model is more agree well with the test data.</jats:p>

A Review on Performance Characteristics of an Air Foil Thrust Bearing

“…Static tests on foil thrust bearings (FTB) with viscoelastic support illustrated an increase in structural stiffness with an increase in axial load while dynamic tests depicted small amounts of axial vibration of the rotor at higher speeds [27]. Novel bearing test rig developed by Xu et al [28] consisted a high speed motor (speeds ranging from 15,000 rpm to 28,000 rpm) with a piston loading device for measuring bearing thrust load for an optimized taper height of the top foil, besides the test results being compared with the computational model developed by them.…”

“…7. Fang Xu [28] showed that 0.2 mm TF and BF mounted on AFTB of 36 mm BD (FSA = 3000 mm 2 ) with a taper height of 20 microns had load capacity of 60 N, 73 N, 78 N, and 100 N corresponding to 15 krpm, 21 krpm, 25 krpm, and 28 krpm speeds. 8.…”