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.

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).

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).

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).