Gas concentration in rarefied flows: Experiments and modeling

Chenbiao Xu; Vanessa J. Murray; Marcin D. Pilinski; Thomas E. Schwartzentruber; Savio J. Poovathingal; Timothy K. Minton

doi:10.1016/j.ast.2023.108568

Gas concentration in rarefied flows: Experiments and modeling

Chenbiao Xu, Vanessa J. Murray, Marcin D. Pilinski, Thomas E. Schwartzentruber, Savio J. Poovathingal, Timothy K. Minton

Research output: Contribution to journal › Article › peer-review

8 Scopus citations

Abstract

The relationship between gas-surface scattering dynamics and flow through conical systems in the rarefied regime has been explored with experimental and computational tools. Molecular beam-surface scattering experiments were used to characterize the inelastic scattering dynamics of Ar and N₂ on a highly oriented pyrolytic graphite (HOPG) surface. These data were then used to develop a gas-surface scattering approach for kinetic fluid simulations, which combines the diffuse scattering and Cercignani-Lampis-Lord (CLL) models. The translational energy and angular flux distributions from the beam-surface scattering experiments were used to obtain the normal energy accommodation (α_n) parameter as well as the effective surface mass (M) in the CLL model. Constant values of α_n=0.9, M = 40 amu for Ar and α_n=0.75, M = 28 amu for N₂ were found to capture the experimental angular flux scattering distributions over a wide range of incident energies and angles. The gas-surface model was subsequently used in direct simulation Monte Carlo (DSMC) simulations of the flux of directed gas flow through a conical concentrator and compared with measurements of gas concentration with a prototype concentrator in separate molecular beam experiments. Comparisons of predicted concentration pressure ratios (pressure in an accommodation chamber with vs. without concentrator) with measured values for three free-stream velocities of Ar and N₂ showed maximum deviations of 4.8% and 9.8% for Ar and N₂, respectively. The simulations show that gas-surface collisions resulting in the loss of the normal component of the incident energy while preserving the tangential momentum of the impinging atom or molecule, resulting in super-specular scattering, lead to higher concentration of gases than purely specular, energy conserving gas-surface interactions. For conical concentrators, with inlet-to-outlet area ratios of 133 and 600, specular reflections result in concentration factors (flux through an orifice with vs. without concentrator) of only ∼8, while super-specular scattering results in concentration factors of 64 and 127, respectively.

Original language	English
Article number	108568
Journal	Aerospace Science and Technology
Volume	142
DOIs	https://doi.org/10.1016/j.ast.2023.108568
State	Published - Nov 2023

Bibliographical note

Publisher Copyright:
© 2023 The Author(s)

Funding

The authors are grateful to Drs. Stojan M. Madzunkov and Murray R. Darrach of the Planetary Surface Instruments Group for financial support. The Planetary Surface Instruments Group is part of the Jet Propulsion Laboratory (JPL), California Institute of Technology, under contract with NASA. Additional support was provided by NASA under Grant Nos. 80NSSC22K0765 and 80NSSC20K1072. We thank Dr. Max Coleman for insightful discussions on this project. The authors are grateful to Drs. Stojan M. Madzunkov and Murray R. Darrach of the Planetary Surface Instruments Group for financial support. The Planetary Surface Instruments Group is part of the Jet Propulsion Laboratory (JPL), California Institute of Technology, under contract with NASA. Additional support was provided by NASA under Grant Nos. 80NSSC22K0765 and 80NSSC20K1072 . We thank Dr. Max Coleman for insightful discussions on this project.

Funders	Funder number
Planetary Surface Instruments Group
National Aeronautics and Space Administration	80NSSC22K0765, 80NSSC20K1072
National Aeronautics and Space Administration
Jet Propulsion Laboratory
California Institute of Technology

Keywords

Direct simulation Monte Carlo (DSMC)
Gas concentration
Gas-surface interactions
Molecular beam scattering
Rarefied flows

ASJC Scopus subject areas

Aerospace Engineering

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10.1016/j.ast.2023.108568

Cite this

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title = "Gas concentration in rarefied flows: Experiments and modeling",

abstract = "The relationship between gas-surface scattering dynamics and flow through conical systems in the rarefied regime has been explored with experimental and computational tools. Molecular beam-surface scattering experiments were used to characterize the inelastic scattering dynamics of Ar and N2 on a highly oriented pyrolytic graphite (HOPG) surface. These data were then used to develop a gas-surface scattering approach for kinetic fluid simulations, which combines the diffuse scattering and Cercignani-Lampis-Lord (CLL) models. The translational energy and angular flux distributions from the beam-surface scattering experiments were used to obtain the normal energy accommodation (αn) parameter as well as the effective surface mass (M) in the CLL model. Constant values of αn=0.9, M = 40 amu for Ar and αn=0.75, M = 28 amu for N2 were found to capture the experimental angular flux scattering distributions over a wide range of incident energies and angles. The gas-surface model was subsequently used in direct simulation Monte Carlo (DSMC) simulations of the flux of directed gas flow through a conical concentrator and compared with measurements of gas concentration with a prototype concentrator in separate molecular beam experiments. Comparisons of predicted concentration pressure ratios (pressure in an accommodation chamber with vs. without concentrator) with measured values for three free-stream velocities of Ar and N2 showed maximum deviations of 4.8\% and 9.8\% for Ar and N2, respectively. The simulations show that gas-surface collisions resulting in the loss of the normal component of the incident energy while preserving the tangential momentum of the impinging atom or molecule, resulting in super-specular scattering, lead to higher concentration of gases than purely specular, energy conserving gas-surface interactions. For conical concentrators, with inlet-to-outlet area ratios of 133 and 600, specular reflections result in concentration factors (flux through an orifice with vs. without concentrator) of only ∼8, while super-specular scattering results in concentration factors of 64 and 127, respectively.",

keywords = "Direct simulation Monte Carlo (DSMC), Gas concentration, Gas-surface interactions, Molecular beam scattering, Rarefied flows",

author = "Chenbiao Xu and Murray, \{Vanessa J.\} and Pilinski, \{Marcin D.\} and Schwartzentruber, \{Thomas E.\} and Poovathingal, \{Savio J.\} and Minton, \{Timothy K.\}",

note = "Publisher Copyright: {\textcopyright} 2023 The Author(s)",

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month = nov,

doi = "10.1016/j.ast.2023.108568",

language = "English",

volume = "142",

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TY - JOUR

T1 - Gas concentration in rarefied flows

T2 - Experiments and modeling

AU - Xu, Chenbiao

AU - Murray, Vanessa J.

AU - Pilinski, Marcin D.

AU - Schwartzentruber, Thomas E.

AU - Poovathingal, Savio J.

AU - Minton, Timothy K.

PY - 2023/11

Y1 - 2023/11

N2 - The relationship between gas-surface scattering dynamics and flow through conical systems in the rarefied regime has been explored with experimental and computational tools. Molecular beam-surface scattering experiments were used to characterize the inelastic scattering dynamics of Ar and N2 on a highly oriented pyrolytic graphite (HOPG) surface. These data were then used to develop a gas-surface scattering approach for kinetic fluid simulations, which combines the diffuse scattering and Cercignani-Lampis-Lord (CLL) models. The translational energy and angular flux distributions from the beam-surface scattering experiments were used to obtain the normal energy accommodation (αn) parameter as well as the effective surface mass (M) in the CLL model. Constant values of αn=0.9, M = 40 amu for Ar and αn=0.75, M = 28 amu for N2 were found to capture the experimental angular flux scattering distributions over a wide range of incident energies and angles. The gas-surface model was subsequently used in direct simulation Monte Carlo (DSMC) simulations of the flux of directed gas flow through a conical concentrator and compared with measurements of gas concentration with a prototype concentrator in separate molecular beam experiments. Comparisons of predicted concentration pressure ratios (pressure in an accommodation chamber with vs. without concentrator) with measured values for three free-stream velocities of Ar and N2 showed maximum deviations of 4.8% and 9.8% for Ar and N2, respectively. The simulations show that gas-surface collisions resulting in the loss of the normal component of the incident energy while preserving the tangential momentum of the impinging atom or molecule, resulting in super-specular scattering, lead to higher concentration of gases than purely specular, energy conserving gas-surface interactions. For conical concentrators, with inlet-to-outlet area ratios of 133 and 600, specular reflections result in concentration factors (flux through an orifice with vs. without concentrator) of only ∼8, while super-specular scattering results in concentration factors of 64 and 127, respectively.

AB - The relationship between gas-surface scattering dynamics and flow through conical systems in the rarefied regime has been explored with experimental and computational tools. Molecular beam-surface scattering experiments were used to characterize the inelastic scattering dynamics of Ar and N2 on a highly oriented pyrolytic graphite (HOPG) surface. These data were then used to develop a gas-surface scattering approach for kinetic fluid simulations, which combines the diffuse scattering and Cercignani-Lampis-Lord (CLL) models. The translational energy and angular flux distributions from the beam-surface scattering experiments were used to obtain the normal energy accommodation (αn) parameter as well as the effective surface mass (M) in the CLL model. Constant values of αn=0.9, M = 40 amu for Ar and αn=0.75, M = 28 amu for N2 were found to capture the experimental angular flux scattering distributions over a wide range of incident energies and angles. The gas-surface model was subsequently used in direct simulation Monte Carlo (DSMC) simulations of the flux of directed gas flow through a conical concentrator and compared with measurements of gas concentration with a prototype concentrator in separate molecular beam experiments. Comparisons of predicted concentration pressure ratios (pressure in an accommodation chamber with vs. without concentrator) with measured values for three free-stream velocities of Ar and N2 showed maximum deviations of 4.8% and 9.8% for Ar and N2, respectively. The simulations show that gas-surface collisions resulting in the loss of the normal component of the incident energy while preserving the tangential momentum of the impinging atom or molecule, resulting in super-specular scattering, lead to higher concentration of gases than purely specular, energy conserving gas-surface interactions. For conical concentrators, with inlet-to-outlet area ratios of 133 and 600, specular reflections result in concentration factors (flux through an orifice with vs. without concentrator) of only ∼8, while super-specular scattering results in concentration factors of 64 and 127, respectively.

KW - Direct simulation Monte Carlo (DSMC)

KW - Gas concentration

KW - Gas-surface interactions

KW - Molecular beam scattering

KW - Rarefied flows

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DO - 10.1016/j.ast.2023.108568

M3 - Article

AN - SCOPUS:85170643653

SN - 1270-9638

VL - 142

JO - Aerospace Science and Technology

JF - Aerospace Science and Technology

M1 - 108568

ER -

Gas concentration in rarefied flows: Experiments and modeling

Abstract

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Funding

Keywords

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