Influence of turbulence on the formation of high nonequilibrium concentrations of atoms and free radicals in diffusion flames
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In the description of chemical reactions between previously unmixed reacting substances, it is frequently assumed that the reaction rate is very large, so that thermodynamic equilibrium is realized at every point of the flow. This assumption makes it possible to reduce the solution of the problem to the description of the concentration field of the inert (not reacting) component. However, in a number of cases such an assumption is inadequate. A characteristic example is provided by the formation of the oxides of nitrogen. In this case, small deviations from equilibrium in the temperatures and concentrations of the main combustion products lead to a large change in the concentrations of the free atoms and radicals [l], with the consequence that the nitrogen oxidation rate changes strongly. Similar problems arise in the analysis of the ignition of fuel by a jet of combustion products. The list of such examples can be extended. Since reactions in a turbulent flow have the main interest, it is natural to consider how the characteristics of turbulence influence the deviations from thermodynamic equilibrium. The present paper is devoted to examination of this question.
KeywordsOxidation Nitrogen Combustion Free Radical Small Deviation
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