Author: Franz Hindelang
Publisher:
ISBN:
Category : Carbon dioxide
Languages : en
Pages : 44
Book Description
The harmonic oscillator rigid-rotator model has been used to calculate the relaxation region behind a shock wave in carbon dioxide. Finite relaxation rates for the three different vibrational modes and two dissociation reactions are included. Models for the coupling between the vibrational relaxation and the dissociation process are based on the assumption that dissociation can proceed from any vibrational level with equal probability. Two different models for the vibrational excitation have been examined. Solutions have been obtained for the interdependent fluid-flow, chemical rate, and vibrational relaxation-rate equations incorporating estimated rate coefficients. Results are presented in the form of flow-field profiles for density, pressure, translational and vibrational temperatures, and species concentrations. The effects of vibrational excitation, vibration-dissociation coupling, and energy exchange between the vibrational modes are investigated. The effect of vibrational relaxation and vibration-dissociation coupling is much stronger in CO2 with three different vibrational modes than in diatomic gases with only a single mode. The results of this study show that the effect of coupled vibrational relaxation and dissociation can sometimes alter the flow-field profiles by a factor of 2 compared to similar calculations without such coupling. For vibrational relaxation the results indicate that the shock-wave profiles depend primarily on the rate at which the translational energy is fed into internal modes and not so strongly on the energy distribution among the modes.
OAR Cumulative Index of Research Results
Technical Abstract Bulletin
Scientific and Technical Aerospace Reports
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 750
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 750
Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Plasma Physics and Magnetohydrodynamics
Author:
Publisher:
ISBN:
Category : Magnetohydrodynamics
Languages : en
Pages : 188
Book Description
Publisher:
ISBN:
Category : Magnetohydrodynamics
Languages : en
Pages : 188
Book Description
A Simplified Molecular Model for Studying Vibration-dissociation Coupling in Fluid Flows
Author: Walter Albert Reinhardt
Publisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 340
Book Description
A simplified mathematical model is derived that is useful for studying the effects of vibration-dissociation coupling in fluid flows. The derivation is based on energy-moment procedure for simplifying the master equations. To obtain the model equations it is assumed that the vibrational energy can be approximated by the introduction of two vibrational temperatures. The effects of molecular anharmonicity are also accounted for in an approximate manner. The parameters contained within the equations are evaluated by making comparisons with experimental data. It is shown that the model contains the minimum required structure allowing favorable agreement with existing experimental data. Numerical solutions are given for the quasi-steady zone behind a normal shock wave, for the complete structure of a shock wave, and for nozzle flow. The results provide the appropriate pre-exponential temperature dependence of the effective dissociation rate, yield and induction time before dissociation is observed, and, in the case of expanding flow, yield one-fourth less effective relaxation time than the Landau-Teller theory. The thermodynamic quantities for the vibrational mode (partition function, internal energy, and specific heat) agree accurately with like quantities evaluated from spectroscopic data. By the introduction of appropriate assumptions it is shown that the equations reduce to a form identical to the Marrone-Treanor model except for a "truncation factor". When the vibrational temperatures are not large, the model is identical to that of Landau and Teller. The numerical procedure used to integrate the system of rate and flow equations is also described.
Publisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 340
Book Description
A simplified mathematical model is derived that is useful for studying the effects of vibration-dissociation coupling in fluid flows. The derivation is based on energy-moment procedure for simplifying the master equations. To obtain the model equations it is assumed that the vibrational energy can be approximated by the introduction of two vibrational temperatures. The effects of molecular anharmonicity are also accounted for in an approximate manner. The parameters contained within the equations are evaluated by making comparisons with experimental data. It is shown that the model contains the minimum required structure allowing favorable agreement with existing experimental data. Numerical solutions are given for the quasi-steady zone behind a normal shock wave, for the complete structure of a shock wave, and for nozzle flow. The results provide the appropriate pre-exponential temperature dependence of the effective dissociation rate, yield and induction time before dissociation is observed, and, in the case of expanding flow, yield one-fourth less effective relaxation time than the Landau-Teller theory. The thermodynamic quantities for the vibrational mode (partition function, internal energy, and specific heat) agree accurately with like quantities evaluated from spectroscopic data. By the introduction of appropriate assumptions it is shown that the equations reduce to a form identical to the Marrone-Treanor model except for a "truncation factor". When the vibrational temperatures are not large, the model is identical to that of Landau and Teller. The numerical procedure used to integrate the system of rate and flow equations is also described.
Bibliography of Scientific and Industrial Reports
Nuclear Science Abstracts
Technical Publications Announcements with Indexes
Author: United States. National Aeronautics and Space Administration
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 588
Book Description
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 588
Book Description
Transfer and Storage of Energy by Molecules: Vibrational energy
Author: George Murray Burnett
Publisher:
ISBN:
Category : Energy transfer
Languages : en
Pages : 440
Book Description
Publisher:
ISBN:
Category : Energy transfer
Languages : en
Pages : 440
Book Description
Air Force Scientific Research Bibliography: 1950-56
Author: Library of Congress. Science and Technology Division
Publisher:
ISBN:
Category : Military research
Languages : en
Pages : 1196
Book Description
Publisher:
ISBN:
Category : Military research
Languages : en
Pages : 1196
Book Description