Processes of Flame Acceleration in Tubes with Obstacles

There are no known models which sufficiently describe all stages of the DDT process, although DDT key parameters can be singled out. In the first place, a combustible mixture should meet conditions allowing detonation propagation (composition, geometry, initial thermodynamic parameters). Besides, an efficient flame accelerating mechanism is required. Finally, it is necessary to create conditions for a mechanism of detonation initiation and evolution, which is of particular interest. 

The most efficient flame accelerating mechanism is development of large-scale combustion front curvature [16]. The front curvature is developed either by multiple interactions between a turbulent combustion front and pressure perturbations (Taylor instability [17]) or the flame interaction with large-scale obstacles located periodically. 

The first case of front curvature development can be observed in smooth tubes (an example of a detailed investigation of the process is turbulent front stability analysis [18]). 

In the second case, the character of the front curvature development depends on the distance between the obstacles that, in the limiting case, can act as sequential orifices forming a series of turbulent jets in the combustible mixture [19]. 

2 Processes of Flame Acceleration in Tubes with Obstacles 

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