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196 FIRE RESEARCH Kuznetsov, V. R. (U . S. S. R.) "Rate of Chemical Reaction and Its Effect on the Process of Droplet Combustion," Inzhenemy t Zhurnall, 344-349 (1962) Trans- lation A D 419229 F T D - T T 63-653 Ai r Force Systems Command, Wright- Patterson Air Force Base, Ohio. This paper presents an approximate solution to an equation derived by Agafonova.' The equation is intended to describe the burning of a spherical fuel droplet in a gaseous oxidizer stream. I t appears that the objective of Agafonova's theory was to account for the influence of a finite chemical reaction rate on the evaporation rate of the droplet, on the fraction of vaporized fuel that ultimately reacts, and on the conditions governing blowoff of the diffusion flame from the forward stagnation region. Some assumptions involved in Agafonova's model are listed by Kuznetsov, although he does not describe the model. The nature of the model is probably best characterized by the first assumption, which states that "the boundary layer on the droplet is equivalent to a certain given film, with identical thickness everywhere." Agafonova's second-order, ordinary diflFerential equation (for temperature as a function of radial coordinate) appears to consist of a heat con- duction term equated to a chemical heat release rate term. Kuznetsov's contribution is to approximate the heat release rate as a rectangular-shaped step function and the temperature profile as a continuous triangular-shaped function, thereby ex- tracting algebraic solutions for the fraction of vaponzed fuel that burns and for flame blowoff conditions. These two results were compared with experiments (again reported by Agafonova) on ethyl alcohol and gasoline droplets The predicted blow- off conditions agreed well wi th experiment, but the predicted fraction of fuel vapor burned agreed poorly (because the effect of wake burning is neglected in the theory, according to Kuznetsov). This theoretical work appears to be mathematically inferior to current Western theoretical work on the problem. However, there is a considerable amount of ex- cellent work being done in Russia on combustion theory, and much of this is not translated into English. On the other hand, the Russian authors exhibit familiarity with the Western work (e.g., Kuznetsov quotes Spalding). Readers interested in turning to the literature to obtain more details of this work may appreaate the following warnings* 1. Agafonova's paper does not appear to have been translated. 2. Kuznetsov's paper is written in such an abbreviated style that i t is difficult to follow in translation. Reference 1 AoAFONOVA, F . A., GuREVicH, M . A , AND TARASOVA, Y E F "Conditions of Stable Combustion of Single Liquid Fuel Droplets," Third All-Union Conference on the Theory of Combustion, Vol 2 (Moscow, 1960) Subject Headings: Droplefs, burning of; Efhyl alcohol, droplef burning. Gasoline, droplet burning; Reaction rate, effect on droplet burning; Rate of reaction. F. A . Wil l iams
