An Experimental Investigation of Molecular Rarefaction Effects in Gas Lubricated Bearings at Ultra-Low Clearances

Hsia, Yiao-Tee; Domoto, G. A.

doi:10.1115/1.3254526

Cited by 246 publications

(153 citation statements)

References 0 publications

Supporting

Mentioning

150

Contrasting

Order By: Relevance

“…Table 1 presents a comparison of the theoretical values of A 1 and A 2 that have been proposed in the literature [9,22,31,[36][37][38][39]. It can be seen that as yet, no agreement has been reached on the correct value of the second-order coefficient.…”

Section: Analytical Models: Second-order Formulationsmentioning

confidence: 95%

Challenges in Modeling Gas-Phase Flow in Microchannels: From Slip to Transition

Barber

Emerson

2006

Heat Transfer Engineering

153

View full text Add to dashboard Cite

show abstract

Section: Analytical Models: Second-order Formulationsmentioning

confidence: 95%

Challenges in Modeling Gas-Phase Flow in Microchannels: From Slip to Transition

Barber

Emerson

2006

Heat Transfer Engineering

153

View full text Add to dashboard Cite

show abstract

“…A gas lubricated inclined plane slider bearing has been examined by Burgdofer (1959) in the slip flow regime using a first-order slip model with the boundary slip velocity given at a mean free path distance from the wall. Hsia & Domoto (1983) incorporated a second-order slip model and Mitsuya (1993) developed a modified second-order slip model through additional physical considerations, referred to as a 1.5-order slip model. Slip effects in a journal bearing were investigated using a first-order model for compressible flow by Malik (1984) and for incompressible flow by Maureau (1997).…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a small gap gas lubricated bearing with Navier slip boundary conditions

2017

View full text Add to dashboard Cite

A gas lubricated bearing model is derived which is appropriate for a very small bearing face separation by including velocity slip boundary conditions and centrifugal inertia effects. The bearing dynamics are examined when an external harmonic force is imposed on the bearing due to bearing begin situated within a larger complex dynamical system. A compressible Reynolds equation is formulated for the gas film which is coupled to the bearing structure through an axial force balance where the rotor and stator correspond to spring-mass-damper systems. Surface slip boundary conditions are derived on the bearing faces, characterised by the slip length parameter. The coupled bearing system is analysed using a stroboscopic map solver with the modified Reynolds equation and structural equations solved simultaneously. For a sufficiently large forcing amplitude a flapping motion of the bearing faces is induced when the rotor and stator are in close proximity. The minimum bearing gap over the time period of the external forcing is examined for a range of bearing parameters.

show abstract

“…Historically, in order to model rarefaction effects in ultra-thin film lubrication, various velocity-slip models have been incorporated into the NS equations for a variety of bearing geometries. [10][11][12][13][14] However, the experiments [15][16][17][18] have shown that the modified Reynolds equations underpredict the pressure rise when the gas thickness is below 250 nm. 1 Recently, a new extended Reynolds equation based on the regularized 13 moment equations and the lubrication theory has been derived for gas slider bearings, but it can only be applied for the Knudsen number up to unity.…”

Section: Introductionmentioning

confidence: 99%

Rarefaction cloaking: Influence of the fractal rough surface in gas slider bearings

Liu

Zhang

et al. 2017

Physics of Fluids

View full text Add to dashboard Cite

This version is available at https://strathprints.strath.ac.uk/61934/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. PHYSICS OF FLUIDS 29, 102003 (2017)Rarefaction cloaking: Influence of the fractal rough surface in gas slider bearings For ultra-thin gas lubrication, the surface-to-volume ratio increases dramatically when the flow geometry is scaled down to the micro/nano-meter scale, where surface roughness, albeit small, may play an important role in gas slider bearings. However, the effect of surface roughness on the pressure and load capacity (force) in gas slider bearings has been overlooked. In this paper, on the basis of the generalized Reynolds equation, we investigate the behavior of a gas slider bearing, where the roughness of the slider surface is characterized by the Weierstrass-Mandelbrot fractal function, and the mass flow rates of Couette and Poiseuille flows are obtained by deterministic solutions to the linearized Bhatnager-Gross-Krook equation. Our results show that the surface roughness reduces the local mass flow rate as compared to the smooth channel, but the amount of reduction varies for Couette and Poiseuille flows of different Knudsen numbers. As a consequence, the pressure rise and load capacity in the rough bearing become larger than the ones in the smooth bearing in the slip and early transition flow regimes, e.g., a 6% roughness could lead to an increase of 20% more bearing load capacity. However, this situation is reversed in the free-molecular flow regime, as the ratio of the mass flow rates between Couette and Poiseuille flows is smaller than that in the smooth channel. Interestingly, between the two extremes, we have found a novel "rarefaction cloaking" effect, where the load capacity of a rough bearing equals to that of a smooth bearing at a certain range of Knudsen numbers, as if the roughness does not exist.

show abstract

An Experimental Investigation of Molecular Rarefaction Effects in Gas Lubricated Bearings at Ultra-Low Clearances

Cited by 246 publications

References 0 publications

Challenges in Modeling Gas-Phase Flow in Microchannels: From Slip to Transition

Challenges in Modeling Gas-Phase Flow in Microchannels: From Slip to Transition

Dynamics of a small gap gas lubricated bearing with Navier slip boundary conditions

Rarefaction cloaking: Influence of the fractal rough surface in gas slider bearings

Contact Info

Product

Resources

About