Calculation of Surface Roughness Effects on Air-Riding Seals

Guardino, C.; Chew, John W.; Hills, Nicholas J.

doi:10.1115/gt2002-30246

Cited by 4 publications

(5 citation statements)

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“…The lift obtained in practice is also likely to be sensitive to surface finish. There is little or no experimental data available for the effect of surface roughness on brush seal behaviour, but it has been shown by Guardino et al (2002) that surface roughness does affect the lift achieved in a Rayleigh pad.…”

Section: 7mentioning

confidence: 99%

Simulation of flow and heat transfer in the tip region of a brush seal

Chew

Guardino

2004

International Journal of Heat and Fluid Flow

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Section: 7mentioning

confidence: 99%

Simulation of flow and heat transfer in the tip region of a brush seal

Chew

Guardino

2004

International Journal of Heat and Fluid Flow

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“…The influence of relative texture depth on the validity of Reynolds equation has also been confirmed by Feldman et al [130] for gas-lubricated parallel surfaces. Inertia effects around groove-like film discontinuities should also be taken into account as demonstrated by Guardino et al [148] and Jarray et al [149]. Through the investigation of the surface roughness effect on air-riding seals, Guardino et al [148] suggested that the difference between the Reynolds equation and full Navier-Stokes equation is less significant for compressible fluids than incompressible conditions.…”

Section: Inertia Effectmentioning

confidence: 99%

“…Inertia effects around groove-like film discontinuities should also be taken into account as demonstrated by Guardino et al [148] and Jarray et al [149]. Through the investigation of the surface roughness effect on air-riding seals, Guardino et al [148] suggested that the difference between the Reynolds equation and full Navier-Stokes equation is less significant for compressible fluids than incompressible conditions. Nonetheless, with the growing interest of hermetic and compact turbomachinery working with dense fluids, such as supercritical CO2 [150,151] whose density and viscosity are comparable to a liquid, the inertia effects will manifest for such applications, particularly for thrust bearings at high-speed operations.…”

Section: Inertia Effectmentioning

confidence: 99%

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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“…According to (11), the analytical expression of the pressure gradient along the z-axis becomes dP dz � 8μQ…”

Section: Mathematical Modelmentioning

confidence: 99%

“…For instance, the pressure in each groove and the leakage in the clearance flm were calculated by Milani [10] based on the Reynolds equation. Since the Reynolds equation is derived from the NS equation, Dong et al [11] compared the diference of pressure distribution between the Reynolds equation and the NS equation and found that the diference exceeds 20% when the clearance flm is greater than 0.413 μm. Furthermore, Guardino et al [12] investigated the diference in various values of the roughness amplitude to the clearance flm ratio and pointed out that the diference increases with the ratio.…”

Section: Introductionmentioning

confidence: 99%

An Accurate Mathematical Model and Experimental Research of Pressure Distribution in the Spool Valve Clearance Film

Chen

Yang

2022

Mathematical Problems in Engineering

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As an actuator control element of the electrohydraulic system in aerospace, airplanes, and other equipment, the spool valve is prone to the “hydraulic lock” problem, which may cause major accidents of these electrohydraulic systems. The grooves engraved on the spool can effectively eliminate this problem by migrating the uneven pressure distribution in the clearance film between the sleeve and the spool. The effect of migrating uneven pressure distribution depends on the groove parameters. This paper proposed an accurate mathematical model with rectangular grooves to investigate the effect. Unlike previous mathematical models based on the Reynolds equation, the proposed model is based on the Navier–Stokes equation, which is more valid in the range where the clearance film thickness is much less than the groove depth. Meanwhile, the mathematical model takes the distributions, width, depth, and the number of grooves into consideration. Then, the proposed mathematical model was used to investigate the effects of mitigating the uneven pressure distribution under various parameters of grooves. To verify the accuracy of the mathematical model, the volume flow leakage in the clearance film obtained by the proposed model and the Reynolds equation, respectively, is compared with that obtained by the experimental test. The comparison results indicate that the results obtained by the Reynolds equation could reach a maximum of 14.75% different from the experimental results, while the results obtained by the NS equation are only 5.57% different under the same conditions, implying that the mathematical model derived from the NS equation is more accurate.

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Calculation of Surface Roughness Effects on Air-Riding Seals

Cited by 4 publications

References 0 publications

Simulation of flow and heat transfer in the tip region of a brush seal

Simulation of flow and heat transfer in the tip region of a brush seal

A Review of Grooved Dynamic Gas Bearings

An Accurate Mathematical Model and Experimental Research of Pressure Distribution in the Spool Valve Clearance Film

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