Mechanism of flame acceleration and detonation transition from the interaction of a supersonic turbulent flame with an obstruction: Experiments in low pressure propane–oxygen mixtures

Enhanced DDT mechanism from shock-flame interactions in thin channels

“…Rather, the formidable flame deformation and its eventual proximity to the Chapman-Jouguet limit appear as the controlling phenomena. This clarifies the emerging picture of DDT, where the proximity of the flame burning velocity to the Chapman-Jouguet value has been identified as a condition for DDT [4,5,8,9,14].…”

“…The problem of shock-flame interactions has attracted much interest, as it is believed to control the transition of deflagrations to detonations (DDT) [1][2][3][4][5][6]. The passage of a shock over the flame provides distortion of the flame front by the Richtmyer-Meshkov instability.…”

“…This deflagration to detonation transition is however highly dependent on the reactivity of the fuel, turbulence intensity and boundary conditions, such as confinement, congestion, etc... [7]. The complexity of the turbulent flame prior to transition to a detonation in typical experiments [1,4] makes it difficult to formulate simple macro-scale conceptual models for DDT, although such attempts have been made in an ad hoc basis [4,5,8,9] with some success. For example, numerical re-construction of Thomas' experiments of shock-flame interactions in a tube have also shown that both turbulence and boundary layer effects are extremely important [10,11] and control the burning rate in a complex manner.…”

“…Recently, the authors [6] have revisited this fundamental problem of shock-flame interaction by attempting to simplify the geometry studied by Thomas, Rakotoarison and their collaborators [1,4,5]. Instead of a spherical flame studied by Thomas leading to a highly convoluted turbulent flame, they considered a planar flame, such that the head-on interaction of a shock and the flame retains the macro-scale one-dimensionality of the problem.…”

Dynamics of cellular flame deformation after a head-on interaction with a shock wave: reactive Richtmyer–Meshkov instability

“…2017; Rakotoarison et al. 2019). Also, the shock reflected from walls or other reflective surfaces may result in multiple interactions, which would lead to more considerable flame acceleration and possibly the deflagration-to-detonation transition (Thomas, Bambrey & Brown 2001).…”