The problem of calculating the flow behind a normal shock front is discussed. The additional complication of finite reaction rate chemistry has been included. A numerical method and several results of flow across a shock wave with an eleven-species, thirteen reaction model of air are presented. Results of the method are discussed and compared with those of Hall, Escheroeder, and Marrone (inviscid hypersonic air flows with coupled non-equilibrium processes. IAS 30th annual meeting, Jan 1962). (Author).

In the present monograph, we develop the kinetic theory of transport phenomena and relaxation processes in the flows of reacting gas mixtures and discuss its applications to strongly non-equilibrium conditions. The main attention is focused on the influence of non-equilibrium kinetics on gas dynamics and transport properties. Closed systems of fluid dynamic equations are derived from the kinetic equations in different approaches. We consider the most accurate approach taking into account the state-to-state kinetics in a flow, as well as simplified multi-temperature and one-temperature models based on quasi-stationary distributions. Within these approaches, we propose the algorithms for the calculation of the transport coefficients and rate coefficients of chemical reactions and energy exchanges in non-equilibrium flows; the developed techniques are based on the fundamental kinetic theory principles. The theory is applied to the modeling of non-equilibrium flows behind strong shock waves, in the boundary layer, and in nozzles. The comparison of the results obtained within the frame of different approaches is presented, the advantages of the new state-to-state kinetic model are discussed, and the limits of validity for simplified models are established. The book can be interesting for scientists and graduate students working on physical gas dynamics, aerothermodynamics, heat and mass transfer, non-equilibrium physical-chemical kinetics, and kinetic theory of gases.

The two chemical reactions given by N2O4 + M = 2NO2 + M = 2NO + O2 + M, where M represents the inert carrier gases argon or nitrogen, were studied. The experiments were carried out in a temperature controlled shock tube and a light absorption technique permitted the time dependent concentration of the species NO2 to be determined. For shock strengths where the temperature did not exceed 400K only the first chemical reaction took place. Stronger shock waves excited both chemical reactions with temperatures up to 2100K, and for this reason, flow fields with two nonequilibrium modes could be investigated. Since the relaxation times of these two reactions were different by about three orders of magnitude, they could be experimentally uncoupled. A study of the reaction mechanisms and rate constants for both reactions was carried out. At shock strengths exciting only the first chemical reaction the complete picture of a non-equilibrium flow field with only one nonequilibrium mode could be investigated. In this situation, the shock strengths were varied from weak, fully dispersed waves to strong, partly dispersed waves. (Author).

Similarity parameters are developed which govern the length of nonequilibrium zones behind normal shock waves. Non-equilibrium effects produced by both vibrational relaxation and dissociation are considered. The parameters can also account for arbitrary levels of free-stream vibrational energy or dissociation level. The validity of the parameters is examined using numerical computations of the properties of the non-equilibrium fields. These computations are made with the aid of experimentally based rate expressions. The parameters, when written in a form describing the variation of non-equilibrium zone length with Mach number, are shown to have acceptable accuracy. (Author).

The method of characteristics for a chemically reacting gas is used in the construction of the time-dependent, one-dimensional flow field resulting from the normal reflection of an incident shock wave at the end wall of a shock tube. Nonequilibrium chemical reactions are allowed behind both the incident and reflected shock waves. All the solutions are evaluated for oxygen, but the results are generally representative of any inviscid, nonconducting, and nonradiating diatomic gas. The solutions clearly show that: (1) both the incident- and reflected-shock chemical relaxation times are important in governing the time to attain steady state thermodynamic properties; and (2) adjacent to the end wall, an excess-entropy layer develops wherein the steady state values of all the thermodynamic variables except pressure differ significantly from their corresponding Rankine-Hugoniot equilibrium values.

This work has addressed the question: What is the effect of nonequilibrium chemical reactions on separated hypersonic flow? The model used to generate the separate flow is a hypersonic shock wave/boundary layer interaction on a flat plate in a high enthalpy flow. The flow was calculated by means of a finite-difference, time-marching solution. The results show that nonequilibrium effects can be important in the separated flow region, and that future applications should be aware of such effects. Keywords: Separated flow, Non-equilibrium, Shock-wave/boundary layer, Boundary layer interaction.

The high temperatures generated in gases by shock waves give rise to physical and chemical phenomena such as molecular vibrational excitation, dissociation, ionization, chemical reactions and inherently related radiation. In continuum regime, these processes start from the wave front, so that generally the gaseous media behind shock waves may be in a thermodynamic and chemical non-equilibrium state. This book presents the state of knowledge of these phenomena. Thus, the thermodynamic properties of high temperature gases, including the plasma state are described, as well as the kinetics of the various chemical phenomena cited above. Numerous results of measurement and computation of vibrational relaxation times, dissociation and reaction rate constants are given, and various ionization and radiative mechanisms and processes are presented. The coupling between these different phenomena is taken into account as well as their interaction with the flow-field. Particular points such as the case of rarefied flows and the inside of the shock wave itself are also examined. Examples of specific non-equilibrium flows are given, generally corresponding to those encountered during spatial missions or in shock tube experiments.