A Technique and Results Obtained in Experimental Studies to Estimate the Load Capacity of Radial Gas Foil Bearings
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RAFT AND ROCKET ENGINE DESIGN AND DEVELOPMENT
A Technique and Results Obtained in Experimental Studies to Estimate the Load Capacity of Radial Gas Foil Bearings Yu. A. Ravikovicha, Yu. I. Ermilova, *, and D. P. Kholobtseva a
Moscow Aviation Institute (National Research University), Volokolamskoe sh. 4, Moscow, 125993 Russia *e-mail: [email protected] Received June 25, 2020; revised July 16, 2020; accepted July 16, 2020
Abstract—The paper includes a technique of estimating the ultimate load capacity of radial gas foil bearings, a test bed and an experimental facility to estimate the ultimate load capacity. The experimental results of studying a 78 mm radial gas foil bearing are given. DOI: 10.3103/S1068799820030101 Keywords: high-speed turbomachines, gas foil bearings, technique of estimating the ultimate load capacity, experimental facility.
Nowadays, gas foil bearings along with active magnetic bearings are the most promising ones for oilfree rotor mounting groups of high-speed turbomachines. More than a dozen of small gas foil bearingequipped turbomachines as well as standard series of gas foil bearings have been developed for turbomachines fitted with rotors weighing from a few hundred grams to 60 kg and heavier [1]. Some of the bearings are intended for airborne turbomachines (cooling turbines, starter-generators, superchargers, small gas turbine engines). There is a demand for higher standards of ultimate load capacity of not only axial but radial gas foil bearings due to high vibratory loads applied from a turbomachine rotor. This paper is a continuation of the works [2, 3], which describe axial gas foil bearings. The load capacity is studied in works [4–8]. Figure 1 shows a variant of a radial gas foil bearing.
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2 3 5 4 Fig. 1.
Shaft 1 is installed in bearing body 2. Foils 3 and wave-shaped springs 5 are placed between the shaft ant the body. The foils are body-fixed with welded keys 4. As the shaft spins, there is an excessive pressure in the converging gap between the shaft and the foils to produce the load capacity. For research purposes a test bed made in Moscow Aviation Institute was used to test gas foil bearings up to 100 mm in diameter and create bearing load up to 4000 N. The maximum shaft rotation speed is 48,000 rpm. 445
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Figure 2 shows the test bed diagram.
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Fig. 2.
Bearing 1 and rotor 2 are placed in experimental facility 3. The rotor is driven through clutch 4 with drive 5. The drive is a high-speed asynchronous motor capable of inverter-assisted speed adjustment. The facility and drive are mounted on rigid support 6 through v-blocks 7. The load on bearings is created by the loader mounted on frame 8, which consists of jack 9, trapezium 10, force meter 11, gimbal 12, and steel belt 13. The trapezium transfers the load from the jack to the force meter 11. The gimbal compensates misalignment of the loader parts. The flexible steel belt with its second edge fixed on body 14, where the bearing is inserted, hel
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