Multitemperature Dissociation Rate of N2+N2→N2+N+N Calculated Using Selective Sampling Quasi-Classical Trajectory Analysis

Voelkel, Stephen; Varghese, Philip L.; Raman, Venkat

doi:10.2514/1.t5103

Cited by 12 publications

(2 citation statements)

References 57 publications

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“…The effect of rotational energy on dissociation is similar but is less pronounced relative to the vibrational energy. Recently, ab initio methods such as direct molecular simulations (DMS) 1,2 , master-equation analysis [3][4][5][6] and quasi-classical trajectory calculations (QCT) 7,8 have quantified the importance of ro-vibrational energy in the state-specific dissociation rates of air species. This has been possible due to recently developed accurate potential energy surfaces (PESs) for N 2 -N 2 and N-N 2 collisions 9,10 , O 2 -O 2 11 and O-O 2 12 collisions, N 2 -O 2 collisions 13 , and N 2 -O collisions 14 for the purpose of studying the air chemistry relevant to hypersonic flows.…”

Section: Introductionmentioning

confidence: 99%

Consistent Kinetic And Continuum Dissociation Models For High-Temperature Air

Singh

Schwartzentruber

2020

AIAA Scitech 2020 Forum

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In this article, we propose a generalized non-equilibrium chemical kinetics model from ab initio simulation data obtained using accurate potential energy surfaces developed recently for the purpose of studying high-temperature air chemistry. First, we present a simple cross-section model for dissociation that captures recent ab initio data accurately. The cross-section model is analytically integrated over Boltzmann distributions and general non-Boltzmann distributions to derive general non-equilibrium dissociation model. The general non-Boltzmann model systematically incorporates key physics such as dependence on translational energy, rotational energy, vibrational energy, internal energy, centrifugal barrier and non-Boltzmann effects such as overpopulation and depletion of high energy states. The model is shown to reproduce the rates from QCT for Boltzmann distributions of internal energy states. Reduced rates in non-equilibrium steady state due to depletion of high internal energy states are also predicted well by the model. Furthermore, the model predicts the enhanced rates as observed due to significant overpopulation of high vibrational states relative to Boltzmann distributions while the gas is in non-equilibrium in the transient phase. The model provides a computationally inexpensive way of incorporating non-equilibrium chemistry without incurring additional cost in the existing computational tools. Further comparisons of the model are carried out in another article, where simplifications to the model are proposed based on the results.

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Section: Introductionmentioning

confidence: 99%

Consistent Kinetic And Continuum Dissociation Models For High-Temperature Air

Singh

Schwartzentruber

2020

AIAA Scitech 2020 Forum

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“…Recently, accurate potential energy surfaces (PESs) have been developed for the purpose of studying air chemistry relevant to hypersonic flows, for instance N 2 -N 2 and N-N 2 collisions 14,15 , O 2 -O 2 16 and O-O 2 17 collisions, N 2 -O 2 collisions 18 , and N 2 -O collisions 19 . Using these PESs, ab initio methods such as direct molecular simulations (DMS) 8,11 , master-equation analysis [20][21][22][23] and quasi-classical trajectory calculations (QCT) 24,25 have quantified the coupling of rovibrational energy to the state-specific dissociation rates of air species. Based on the obtained ab initio data, a nonequilibrium dissociation model has been derived using first principles by the authors in Refs.…”

Section: Introductionmentioning

confidence: 99%

Consistent Kinetic-Continuum Recombination Model for High Temperature Reacting Flows

Singh,

Schwartzentruber

2020

Preprint

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A recombination reaction model for high-temperature chemical kinetics is derived from ab initio simulations data. A kinetic recombination rate model is derived using a recently developed ab initio state-specific dissociation model 1 and the principle of microscopic reversibility. When atoms recombine, the kinetic rate model shows that product molecules have high favoring for high vibrational energy states. A continuum recombination rate model is then derived analytically from the kinetic recombination rate model. Similarly, the expression for the average vibrational energy of recombining molecules is also derived analytically. Finally, a simple model for non-Boltzmann vibrational energy distribution functions is derived. The distribution model includes both depletion of energy states due to dissociation and re-population of states due to recombination where a Boltzmann distribution is recovered in chemical equilibrium. Isothermal relaxation simulations using the continuum dissociation and recombination model are performed and the results are compared with the state-of-the-art model.

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Modelling of vibrational nonequilibrium effects on the H2–air mixture ignition under shock wave conditions in the state-to-state and mode approximations

Kadochnikov

Arsentiev

2020

Shock Waves

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Multitemperature Dissociation Rate of N2+N2→N2+N+N Calculated Using Selective Sampling Quasi-Classical Trajectory Analysis

Cited by 12 publications

References 57 publications

Consistent Kinetic And Continuum Dissociation Models For High-Temperature Air

Consistent Kinetic And Continuum Dissociation Models For High-Temperature Air

Consistent Kinetic-Continuum Recombination Model for High Temperature Reacting Flows

Modelling of vibrational nonequilibrium effects on the H2–air mixture ignition under shock wave conditions in the state-to-state and mode approximations

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