The Classification of the Scenarios of Fast Combustion Wave Development and Deflagration-to-Detonation Transition in Cha
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USTION, EXPLOSION, AND SHOCK WAVES
The Classification of the Scenarios of Fast Combustion Wave Development and Deflagration-to-Detonation Transition in Channels A. D. Kiverina, *, A. E. Smygalinaa, and I. S. Yakovenkoa aJoint
Institute for High Temperatures, Russian Academy of Sciences, Moscow, 125412 Russia *e-mail: [email protected] Received January 15, 2020; revised January 15, 2020; accepted February 20, 2020
Abstract—This work presents the review and classification of the scenarios of the development of the final stage of flame acceleration in channels and tubes including the transition to detonation on the flame front and formation of the conditions for kernel ignition ahead of the front. An approach to the numerical assessment of the detonability of combustible gaseous mixtures is formulated based on the classification of highspeed combustion modes proposed by the authors, and the general possibility of the practical application of such an approach is shown. The quantitative estimates of the critical conditions for the stable detonation formation as a result of flame acceleration and upon the transmission of the detonation wave, which are in agreement with the available published experimental data, are presented. Keywords: accelerated flame, deflagration-to-detonation transition, detonability, critical conditions, hydrogen, acetylene DOI: 10.1134/S1990793120040168
INTRODUCTION One of the promising approaches to the energyeffective use of combustible gaseous mixtures is their combustion in the detonation mode. Currently, engines with continuous detonation combustion in an annular combustion chamber can be distinguished among the concepts of steady-flow ramjet engines being developed [1]. Controlled initiation of detonation and further stabilization of detonation in the combustion chamber should be considered as the main problems related to the development of engineering systems of such a type. For the solution of both problems, the precise determination of the limits of detonation formation and its stability under the set conditions is of fundamental interest. The chemical composition of the mixture being used and its thermodynamic state when preparing and feeding it to the duct of the combustion chamber should be considered as the primary factors determining the criteria of the stable formation and development of detonation. At present, a common method for the initiation of detonation is its formation as a result of flame acceleration in an individual channel (a forechamber) and transmission to the main duct of the combustion chamber [1, 2]. The forechamber is generally filled with the most chemically active mixture capable of detonation under the conditions being implemented. The process of the formation of detonation as a result
of flame acceleration, deflagration-to-detonation transition (DDT), and the process of transmission followed by the initiation of detonation in the main duct depend in a certain way on the chemical composition of the mixture being used and its thermodynamic state. As shown
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