ABSTRACT

Thus, depending on the ratio o f the kinetic rate constants o f the reactions in the condensed and gas phases, different structures o f the combustion front and various combustion modes are possible: the induction, mixed, and conjunction modes, in which the combustion characteristics have various functional dependences on the determining parameters. In this connection, let us consider critically a widely used concept o f "flame standoff. A number o f models with a complex combustion mechanism were developed in the literature based on this concept. Possessing a number of advantages, such as a relative simplicity and clearness, these concepts demonstrate certain shortcomings, which restrict their application: 1. Actual ly, the dependence o f the width of the standoff zone (the "dark zone") x m on the combustion parameters is obtained based on the dimension reasoning and, in this case, the relation between the kinetic and thermodynamic constants of the gas-phase reaction and the combustion rate is too simplified, and, thus, a special analysis is required. 2. The dependence presented can be used within particular limits, when the value o f xm corresponds to the width of the heating zone by the order o f magnitude and cannot be applied for the induction and conjunction mechanisms. 3. The validity o f application o f the "flame standoff concept for the quantitative estimates of combustion characteristics needs further examination by the solution of the problem in a rigorous formulation and with the help of numerical calculations.