Acceleration of the Flame in a Smooth Channel and Detonation Transition

In the work, the authors have presented a systematization of the data on acceleration of the flame in a smooth channel filled with gaseous fuel mixture. A mixture of acetylene and oxygen, for which novel experimental and calculation- theoretical investigations have been carried out, was selected as an example of the fuel mixture. On the basis of comprehensive analysis, the authors have described in detail all stages of development of the process, including the initial stage of exponential acceleration of the flame, the stage of restructuring of the flame front accompanied by its retardation, the resumption of flame acceleration, and the creation of conditions for detonation transition. It has been demonstrated that of paramount importance in the development of each stage are hydrodynamic processes determining, in particular, the behavior of the flame in the flow formed in the channel and its acceleration and the compression of the fuel mixture, which is coordinated with it. This leads to the creation of conditions for the formation of detonation. Importantly, the carried-out calculations reproduce, at a qualitative level, all stages of development of the flame, and a parametric analysis of conditions for the transition to detonation quantitatively predicts, with a good degree of accuracy, the critical detonation-transition conditions determined experimentally.