Abstract
The use of Gas Foil Bearings (GFBs) can facilitate an environmentally friendly and oil-free alternative for high-speed rotating light machinery. The applicability is, however, drastically limited by their low load-bearing capability and inherently low damping. One possible way to mitigate these limitations is through hybridisation and active feedback control. This paper exemplifies the possibilities of using passive Hybrid Gas Foil Bearings (HGFBs) with radial gas injection to increase the load-bearing capacity and the stability of a rotor-bearing system. With hybridisation comes also the possibility of active feedback control, to this extent, the paper presents a step-by-step methodology for designing feedback control for an active HGFB. The non-linear set of differential equations comprising the system, pressure states, foil deflections, rotor movements, and actuator position, are solved simultaneously with control feedback. The hybrid system is presented for a yet-to-be-built version of an existing industrial-scale GFB test rig augmented with an existing injection system. The industrial-scale test rig mimics an 120 kW compressor weighing 21.17 kg used for water treatment. The presented results comprise pressure distributions, film height, foil deformation, Campbell diagrams, eccentricity diagrams, and waterfall plots. The augmentation with radial injection is seen to greatly improve the system’s capabilities, i.e., a significant enlargement of operational speed range from 30 kRPM to 40 kRPM (33 %), and start-ups without dry friction between the rotor and top foil, and an increase in load capacity described through rotor position.
Original language | English |
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Article number | 118301 |
Journal | Journal of Sound and Vibration |
Volume | 578 |
Number of pages | 27 |
ISSN | 0022-460X |
DOIs | |
Publication status | Published - 2024 |
Keywords
- Active feedback control
- Controllable and hybrid air lubrication
- Gas foil bearings
- Load carrying capacity
- Stability
- Sub-synchronous vibration