Reaction surface (flame-sheet) model in the theory of combustion of unmixed fuels. Molecular-kinetic solution in the reaction region

Abstract

In the first part [1] of this investigation, a study was made of the main characteristic features of the flow resulting from the mixture of two flows with components that enter into an irreversible chemical reaction. The main errors in the solution of the corresponding gas-dynamic problem resulting from the use of various assumptions were also analyzed. It was found that the influence of the usually ignored Burnett and super-Burnett terms in the transport properties (i.e., in the stress tensor and in the heat flux and diffusion vectors) can be much stronger in this problem than in ordinary mixing problems. In the present, second part, a molecular-kinetic study is made of the flow in the thin reaction region. For the finding of the “external” solution of the problem in the mixing layer or when the classical flame-sheet model is used, this region is treated as a surface in the flow field on which all the chemical transformations of the components of the gas mixture take place. Gas-dynamic equations are obtained that describe the main and some of the subsequent approximations in the reaction region; these equations confirm the arguments put forward in the first part concerning the part played by the non-Navier-Stokes terms in the transport properties.