Abstract
Foil bearing provides compliant support and moderate Coulomb friction for rotor-bearing system, which is conducive to stability and reliability of high speed rotating machinery. In this paper, both hydrodynamic lubricated foil journal and foil thrust bearings are applied in a 150 m3·h−1 turboexpander for air separation. In the bearings, protuberant foil is chosen as the supporting subfoil due to its merits of easy fabrication and assembly. Static loading and deflection of the bearings are tested, respectively, before integration into the turboexpander. Afterwards, the loading and deflection curves of the journal and thrust bearings are polynomial fitted using least-square method. Then, performance tests are carried out on the rotor-bearing system, including transient speed-up, high speed, and speed-down processes. In the tests, the turboexpander supported by the hydrodynamic foil bearings operates smoothly with repeatability. Maximal rotor speed of the turboexpander reaches 52000 rpm with hydrodynamic lubricated protuberant foil bearings.
Highlights
Turboexpander is an indispensable component in energy conversion system
In order to reduce the friction torque at the start-up stage, the nominal journal bearing clearance is increased to 100 μm. Transient processes such as start-up, high speed, and speed-down of the rotor supported by integrated foil journal bearing and thrust bearing are tested after assembly of the turboexpander
Foil bearing supporting technology using both protuberant foil journal and thrust bearings is developed for the turboexpander
Summary
Turboexpander is an indispensable component in energy conversion system. Higher speed is anticipated for the turboexpander in pursuit of high efficiency [1]. Kim et al applied foil thrust bearing and journal bearing in a 66 mm diameter 75 kW turbo blower with rotor speed of 30000 rpm, and subsynchronous rotor lateral motions appeared [23]. Two kinds of journal bearings, copper wire support and viscoelastic support, were compared for small cryogenic turboexpander of 12 mm diameter around 220000 rpm [6]. Bump foil journal bearings was applied in the above turboexpander that could operate smoothly in a wide speed range [25]. Static structure stiffness and load capacities of the thrust bearing were tested in transient start-up and speed-down processes [29, 30]. Hydrodynamic lubrication using both protuberant foil journal and thrust bearings (integrated aerodynamic foil bearing supporting technology) in the turboexpander has not been tested yet. Static loading and unloading of the foil journal bearing and thrust bearing are tested
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