Flow of a Rarefied Gas in a Tube of Annular Section

Bassanini, Piero

doi:10.1063/1.1761817

Cited by 29 publications

(13 citation statements)

References 2 publications

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“…The outgoing boundary distributions / þ , appearing in Eqs. (18)- (21), are given by the boundary conditions (7)-(10), depending on which of the four boundaries a characteristic line will terminate. Finally, the parameters q i , with i ¼ L; B; R; T appearing in the boundary conditions are obtained by substituting (16) into Eqs.…”

Section: Formulation Of the Integro-moment Equationsmentioning

confidence: 99%

“…These pitfalls are circumvented in the formulation and implementation of the IMM. Over the years the IMM has been implemented mainly to problems in slab and axisymmetric geometries [20][21][22][23][24][25][26][27][28]. More recently, it has been demonstrated that the IMM can be applied to solve two-dimensional rarefied gas flows through channels of various cross sections [29,30].…”

Section: Introductionmentioning

confidence: 99%

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Application of the integro-moment method to steady-state two-dimensional rarefied gas flows subject to boundary induced discontinuities

Varoutis

Valougeorgis

Sharipov

2008

Journal of Computational Physics

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Section: Formulation Of the Integro-moment Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of the integro-moment method to steady-state two-dimensional rarefied gas flows subject to boundary induced discontinuities

Varoutis

Valougeorgis

Sharipov

2008

Journal of Computational Physics

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Section: Survey Of Prior Artmentioning

confidence: 70%

“…In the latter case, in order to check the validity of the various equations derived on the bases of the kinetic theory, only low molecular weight gases (i.e., H2, He, 02, N2, air and COz) were experimented with. Although there was a general agreement in both the old (23, 24) and the new (25,26,27) data closely approaching the molecular flow limit, there were significant deviations in the bordering flow regimes.With the advent of space flight and the corresponding intensive ultrahigh-vacuum laboratory testing, several workers tried to establish the applicability of the annular molecular flow formulae to high molecular weight organic lubricant vapors. They met with considerably less success than those performing the original research.…”

mentioning

confidence: 64%

Labyrinth Sealing of Aerospace Mechanisms—Theory and Practice

Gardos¹

1974

A S L E Transactions

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High-vacuum naphthalene evaporation loss experimentswere conducted with a specially designed annular effusion cell to examine the validily of the most frequently used theoretical models of molecular $ow, specijcally applied to a high molec-; ular weigh1 organic compound. Literature data are similarly correlated to (a) show the respective accuracy of the various formulae and ( b ) discuss the mosl prevalent effusion experimental errors often causi?zg orders of magnitude d qferences between theoretical predictions and experimental results. A simplijed molecular $ow effusion model i s proposed, modi$ed to account for the evaporation rate and rate of vapor pressure change of polymeric lubricating oils. The results and conclusions are useful for accurale prediclions of long-term lubricant loss lhrough annular-design labyrinth seals of wet-lubricated aerospace mechanisms and vacuum chamber components. INTRODUCTION Currently there are no reliable performance prediction techniques dealing with the friction and wear life of drylubricated spacecraft components. Consequently, whenever possible, the use of low volatility oils and greases is preferred.For example, methods predicting bearing or gear fatigue (catalog) life based strictly on structural design and alloy selection are generally available. Further incorporation of the elastohydrodynamic theory is useful for oil-lubricated bearing or gear performance prognosis, provided that the mechanisms operate at known speeds, loads and temperatures (1, 2, 3). At the present time, however, each dry lubricant application must be life tested to establish confidence in completing an individual mission (4). NOMENCLATURE A = evaporation area, cm2 6 = molecular diameter, cm j = fraction of molecules diffusely reflected F = volume effusion rate, I .~e c -~ Fl = volume effusion rate, through the annular space only, I-sec-I F2 = volume effusion rate, through the annular orifice only, I-sec-I G = free-surface evaporation rate, g.~m-~.sec-' GT = time-dependent free-surface evaporation rate of polymeric fluids, g.~m-~.sec-' K = transmission probability (conductance) factor, dimensionless L = annular channel length, cm A = mean free path, cm m = molecular mass, g M = molecular weight, g 0 = circumference of the effusion channel, cm p = vapor pressure, torr Ap = pressuredifferential between the chamber or space vacuum and thevapor pressure= vapor pressure of the effusing compound, torr rr = 3.1415 Q = volume conductance a t a given pressure, torr.l.sec-I & = gas constant, 62.36 torr.1-T1-M-I R, = inner annular radius, cm Rr = outer annular radius, cm p = density, g -~m -~ L = time, sec T = absolute temperature, K V = vapor volume, 1 v, = average molecular velocity, cm.sec-' w = weight, g --dw -effusion weight loss, g-sec-I dl X = characteristic dimension of the effusion system, cm X/A = Knudsen number, dimensionless Downloaded by [University of California, Los Angeles (UCLA)] at 21:59 21 June 2016With wet lubrication of aerospace mechanisms, the volatility characteristics of the oils and ...

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“…The collision frequency v in equation (6). may be taken pruvurtional to n~ or to n ~(1 + -2 t)(l + TJ) so that the ratio v/v to first order is…”

mentioning

confidence: 99%

Internal Rarefied Gas Flows With Backscattering. Part 3. Kramer's Problem: The Effect of Backscattering on Slip.

Berman¹

1971

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Flow of a Rarefied Gas in a Tube of Annular Section

Cited by 29 publications

References 2 publications

Application of the integro-moment method to steady-state two-dimensional rarefied gas flows subject to boundary induced discontinuities

Application of the integro-moment method to steady-state two-dimensional rarefied gas flows subject to boundary induced discontinuities

Labyrinth Sealing of Aerospace Mechanisms—Theory and Practice

Internal Rarefied Gas Flows With Backscattering. Part 3. Kramer's Problem: The Effect of Backscattering on Slip.

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