Author: Charles E. TreanorPublisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 46
Book Description
Vibrational Relaxation Effects in Dissociation Rate-constant Measurements
Author: Charles E. TreanorPublisher:
ISBN:
Category : Chemical kinetics
Languages : en
Pages : 42
Book Description
The Effect of Dissociation on the Rate of Vibrational Relaxation
Author: Charles E. TreanorPublisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 46
Book Description
Coupled Vibration and Dissociation Relaxation Behind Strong Shock Waves in Carbon Dioxide
Author: Franz HindelangPublisher:
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.
Two Different Interpretations of Measured Dissociation-rate Constants and Their Effects on Coupled Vibrational-dissociational Flows of Oxygen Over a Wedge
Author: Fred R. DeJarnettePublisher:
ISBN:
Category : Coupling constants
Languages : en
Pages : 34
Book Description
The Coupling of Vibrational Relaxation and Dissociation
Author: M. GreenblattPublisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 68
Book Description
Vibration and Dissociation Coupling Behind Strong Shock Waves
Author: Charles E. TreanorPublisher:
ISBN:
Category : Dissociation
Languages : en
Pages : 48
Book Description
The coupling between vibrational relaxation and dissociation is discussed. A model for computations of dissociation behind strong shock waves is presented. It is shown that the loss of vibrational energy during dissociation introduces an inverse temperature dependence into the observed dissociation rate of O2 between 4000 and 8000K. Changing the model so that dissociation from higher vibrational levels is enhanced results in a dissociation-incubation time immediately behind the shock. The vibrational-energy distribution behind the shock is calculated, and shown to depart considerably from a Boltzmann distribution. The molecular model, which uses a Boltzmann distribution, is shown to give the same result as the non-Boltzmann model for both the nonequilibrium dissociation rate and the dissociation incubation time. (Author).
A Simplified Molecular Model for Studying Vibration-dissociation Coupling in Fluid Flows
Author: Walter Albert ReinhardtPublisher:
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.
Chemical Relaxation with Preferential Dissociation from Excited Vibrational Levels
Author: Paul V. MarronePublisher:
ISBN:
Category : Chemical reactions
Languages : en
Pages : 60
Book Description
Vibrational Energy Relaxation and Dissociation in
Author: A. W. AliPublisher:
ISBN:
Category :
Languages : en
Pages : 55
Book Description
A master equation is solved for a nitrogen discharge to determine the vibrational energy relaxation and dissociation. The master equation includes the effects of electron collisions with the molecule, the vibrational-vibrational energy exchange and vibrational-translational energy conversion between the molecules. The establishment of a vibrational distribution is described by a vibrational temperature which is nearly Boltzman and its obtained from the density of 31 vibrational levels. For most conditions the dissociation rate via the vibrational ladder is higher for higher vibrational temperatures. The vibrational temperature is generally depressed due to V-V and T-V effects. (Author).
Author: David A. Gonzales