Mean Free Path Effect in Spiral-Grooved Thrust Bearings

Hsing, F. C.; Malanoski, S. B.

doi:10.1115/1.3554901

Cited by 10 publications

(3 citation statements)

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“…Their results suggested that the local incompressibility effect overestimated the pressure rise within the fluid film due to both the compressibility and the rarefaction effects. Comparison with experimental data showed that their model performed better than the classical NGT model such as applied by Hsing and Malanoski [119].…”

Section: λ = −mentioning

confidence: 93%

“…The effect scales with the mean free molecular path. If the ratio between the clearance and the molecular mean free path drops below a threshold value, rarefaction effects start manifesting [1,119,136,137] resulting in a departure from the zero-velocity flow condition at the boundaries. The Knudsen number Kn, defined as the ratio between the molecular mean free path and the fluid film thickness, indicates the severity of rarefaction effect.…”

Section: Rarefaction Effects and Slip-flow Boundariesmentioning

confidence: 99%

“…The rarefaction effect can be considered either by correcting the classical continuous fluid equations by including a slip flow boundary conditions at the wall surfaces [138,141] or by deriving the governing equation from the Boltzmann equation (accounting for molecular behavior) [137,142]. Hsing and Malanoski [119] found deviations up to 20% between stiffness obtained from models with and without the rarefaction effect at Kn=0.1 for an SGTB, thus suggesting a significant impact on the bearing performance. Shukla et al [141] suggested that the gas-bearing load capacity decreased with increasing Kn.…”

Section: Rarefaction Effects and Slip-flow Boundariesmentioning

confidence: 99%

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A Review of Grooved Dynamic Gas Bearings

Guenat

Schiffmann

2019

Applied Mechanics Reviews

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This paper offers an extensive review of publications dealing with the modeling, the design, and the experimental investigation of grooved dynamic gas-lubricated bearings. Recent years have witnessed a rise in small-scale and high-speed turbomachinery applications. Besides the well-known gas foil bearings, grooved bearings offer attractive advantages, which unveil their potential in particular at small scale due to the structural simplicity as well as satisfying predictability. This paper starts with a general background of the application of gas-lubricated bearings and introduces and compares the different gas bearing topologies. Further, the state-of-the-art modeling of grooved gas-lubricated bearings is introduced, systematically assessing the advantages and inconveniences of two major approaches, i.e., the narrow groove theory (NGT) and direct discretization method. Since the NGT method is an elegant and efficient approach to model the complex effects of periodic grooves, a critical section is dedicated to the NGT. In a second phase, different models to include additional physical phenomena such as real gas lubrication, rarefaction, or turbulence effects are reviewed. The paper concludes with a critical assessment of the state-of-the-art and indicates potential fields of research that would allow to shed more light into the understanding of these bearings, as well as with some thoughts on the integrated design methodologies of gas bearing supported rotors.

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Section: λ = −mentioning

confidence: 93%