경사형과 계단형 리세스를 갖는 가압형 가스 포일 스러스트 베어링의 하중지지 성능 예측
Predictions of Load Support Performance of a Pressurized Gas Foil Thrust Bearing with Sloped and Stepped Recesses
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Gas foil thrust bearings (GFTBs) support axial loads in oil-free, high speed rotating machinery using gas as a lubricant. However, under low-speed and high-load conditions, such a bearing experiences friction, leading to wear and a reduced lifespan. Therefore, a pressurized GFTB (PGFTB) that combines hydrostatic and hydrodynamic lubrication by supplying pressurized gas through the supply hole of the top foil has been developed, and various studies have been conducted. In this study, we develop mathematical models of PGFTBs with sloped and stepped recesses and predict its load support performance. The PGFTB maintains a minimum film thickness of approximately 20 μm at rest (0 rpm), regardless of the type of recess, indicating a sufficient hydrostatic pressure to lift the runner at a low rotor speed. Furthermore, the minimum film thickness increases slightly as the numbers of feed holes in the in- and outward radial directions relative to the centerline of the PGFTB pad increase. These findings highlight the importance of supply hole placement in enhancing load support performance. As the rotor speed increases, the minimum film thickness increases rapidly, regardless of the number of supply holes, and without pressurization, sufficient hydrodynamic pressure is generated to lift the runner upon exceeding a certain rotor speed. When comparing the sloped and stepped recesses, the PGFTB with the sloped groove exhibits a superior overall load support performance.
Abstract
Gas foil thrust bearings (GFTBs) support axial loads in oil-free, high speed rotating machinery using gas as a lubricant. However, under low-speed and high-load conditions, such a bearing experiences friction, leading to wear and a reduced lifespan. Therefore, a pressurized GFTB (PGFTB) that combines hydrostatic and hydrodynamic lubrication by supplying pressurized gas through the supply hole of the top foil has been developed, and various studies have been conducted. In this study, we develop mathematical models of PGFTBs with sloped and stepped recesses and predict its load support performance. The PGFTB maintains a minimum film thickness of approximately 20 μm at rest (0 rpm), regardless of the type of recess, indicating a sufficient hydrostatic pressure to lift the runner at a low rotor speed. Furthermore, the minimum film thickness increases slightly as the numbers of feed holes in the in- and outward radial directions relative to the centerline of the PGFTB pad increase. These findings highlight the importance of supply hole placement in enhancing load support performance. As the rotor speed increases, the minimum film thickness increases rapidly, regardless of the number of supply holes, and without pressurization, sufficient hydrodynamic pressure is generated to lift the runner upon exceeding a certain rotor speed. When comparing the sloped and stepped recesses, the PGFTB with the sloped groove exhibits a superior overall load support performance.
참고문헌 (9)
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