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Titolo:
NONEQUILIBRIUM VIBRATION-DISSOCIATION PHENOMENA BEHIND A PROPAGATING SHOCK-WAVE - VIBRATIONAL POPULATION CALCULATION
Autore:
LORDET F; MEOLANS JG; CHAUVIN A; BRUN R;
Indirizzi:
UNIV AIX MARSEILLE 1,LAB SETT MHEQ,CASE 321 F-13397 MARSEILLE 20 FRANCE UNIV AIX MARSEILLE 1,LAB SETT MHEQ F-13397 MARSEILLE 20 FRANCE
Titolo Testata:
Shock waves
fascicolo: 6, volume: 4, anno: 1995,
pagine: 299 - 312
SICI:
0938-1287(1995)4:6<299:NVPBAP>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Keywords:
VIBRATION-DISSOCIATION; VIBRATIONAL POPULATIONS; RATE CONSTANTS; VIBRATIONAL CROSS-SECTIONS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
30
Recensione:
Indirizzi per estratti:
Citazione:
F. Lordet et al., "NONEQUILIBRIUM VIBRATION-DISSOCIATION PHENOMENA BEHIND A PROPAGATING SHOCK-WAVE - VIBRATIONAL POPULATION CALCULATION", Shock waves, 4(6), 1995, pp. 299-312

Abstract

An analysis of nonequilibrium phenomena behind a plane shock is presented concerning the vibrational relaxation and the dissociation of a pure diatomic gas. In the first part, the temperature range is 600 K- 2500 K and the dissociation processes are neglected. The population of each vibrational level is computed by solving relaxation and conservation equations. The relaxation process is described by the master equations of each vibrational level. The vibrational transition probabilities appearing in the relaxation equations are calculated analytically and take into account the anharmonicity of molecular vibration and the potential angular dependence. The populations obtained are compared tothose calculated using a Treanor model and to those calculated with anonequilibrium Boltzmann distribution. For moderately high levels significant differences may be observed. The importance of the V-V process is found to be weak for the transitions involving the lowest levels. In the second part, the temperature range is 2500 K-5500 K and the dissociation process is taken into account as well as the gas dynamic behavior which did not appear in several recent works. The kinetic equations are transformed to obtain a first order differential system and the resolution of such a system coupled with the conservation equationsleads to the population of each vibrational level. The vibrational transition probabilities associated with the atom-molecule interaction are deduced from the cross section calculation used in the first part. The bound-free transition probabilities are obtained, following Marrone and Treanor, assuming that dissociation must occur preferentially from the higher vibrational states: the Marrone and Treanor probability model is extended and employed with an anharmonic oscillator. In the present investigation, behind the shock wave, the evolution of the population distribution expressed as a function of the distance is not monotonous: a lag time appears as shown experimentally in previous works for the macroscopic parameters. For moderately high levels the influence of the anharmonicity and those of the V-V processes appear significant and strongly related. In a general way, in both temperature rangesinvestigated, the V-V processes reduce the effects of the T-V transfer. Finally the influence of the ''characteristic probability temperature'' U of Marrone and Treanor is analyzed and a method of determination of local varying U is proposed.

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Documento generato il 20/01/21 alle ore 12:51:44