Collision of transverse detonation waves in gases

Numerical study of cellular detonation structures of methane mixtures

“…1b, one can see a significant amount of unburned pieces of gas at a considerable distance behind the leading shock front of the DW. The formation of these packages is in agreement with experimental observations (Subbotin, 1975;Kiyanda and Higgins, 2013). This phenomenon was not observed in simulations of regular mixtures based on hydrogen (Trotsyuk, 1999;Vasil'ev & Trotsyuk, 2003).…”

Influence of turbulent fluctuations on detonation propagation

“…Feature (6), in figure 18, is a new pocket of unburned gas that forms along slip lines associated with the collision process. In fact, the formation of such pockets, in this manner, is typical of irregular detonation propagation (Subbotin 1975;Kiyanda & Higgins 2013;Austin 2003;Radulescu et al 2005;Oran et al 1982;Radulescu et al 2007). Finally, feature (7), in figure 18, is a bifurcation observed on the Mach shock of feature (3), owing to the unstable nature of methane-air detonations.…”

“…This was shown to be the case for regular detonations where the structure is well predicted by considering only the ignition delay history of a shocked particle, where transport mechanisms have been neglected (Edwards & Jones 1978). For irregular mixtures, many experiments (Kiyanda & Higgins 2013;Austin 2003;Strehlow 1968;Radulescu et al 2005;Subbotin 1975) have shown that a very different cell pattern exists. Typically, irregular mixtures correspond to hydrocarbon fuels with oxygen or air.…”

“…The cell sizes are much more variable, and sometimes contain what appears to be cells within cells; a smaller cell structure within a much larger, and more prominent, cell structure. Furthermore, a number of experiments have shown the wave front to be highly turbulent, often giving rise to shocked unburned pockets of reactive fuel in its wake (Subbotin 1975;Kiyanda & Higgins 2013;Austin 2003;Radulescu et al 2005;Oran et al 1982). An example experiment (Radulescu et al 2007) for an irregular detonation wave, involving methane-oxygen, is shown in figure 2.…”

Viscous solution of the triple-shock reflection problem

“…The shocks then reflect off each other, forming a pair of triple points which move apart as seen in the next three frames. The path of the triple points Superimposed schlieren photographs (cropped, with grain extraction and stretched contrast) of two triple points colliding in a detonation, adapted from Bhattacharjee [8] (CH 4 +2O 2 ,p 0 = 3.5 kPa,T 0 = 300 K, ∆t = 11.53 µs), dark features show a decrease in density and bright features show an increase from left to right, dotted line represents the axis of symmetry, a) reflected (transverse) shock, b) prereflection incident shock, c) triple point, d) contact surface, e) pre-reflection Mach stem, f) post-reflection incident shock, g) triple point, h) post-reflection Mach stem over time form the cellular structure, whose dynamics have been well studied in the past [3][4][5][6][7]. Numerous studies have examined these shock reflections, seeking insight on the phenomena responsible for the creation of locally over-driven detonations, or reinitiation in cases of detonation failure.…”