Detonation structures behind oblique shocks

Abstract

Detonation structures generated by wedge-induced, oblique shocks in hydrogen-oxygennitrogen mixtures were investigated by time-dependent numerical simulations. The simulations show a multidimensional detonation structure consisting of the following elements: (1) a nonreactive, oblique shock, (2) an induction zone, (3) a set of deflagration waves, and (4) a "reactive shock," in which the shock front is closely coupled with the energy release. In a wide range of flow and mixture conditions, this structure is stable and very resilient to disturbances in the flow. The entire detonation structure is steady on the wedge when the flow behind the structure is completely supersonic. If a part of the flow behind the structure is subsonic, the entire structure may become detached from the wedge and move upstream continuously.

On the transition pattern of the oblique detonation structure

“…Experimentally, Maeda et al (2011) recently studied the oblique detonation induced by a hypersonic spherical projectile and the 'straw hat' type of oblique detonation waves is observed. This structure is similar to the structure proposed by Li et al (1994), although the oblique shock before the transition becomes a curved one.…”

“…Furthermore, this structure is found to be stable and resilient to the inflow disturbances according to the numerical results. Viguier et al (1997) studied the oblique detonations in hydrogen-air mixtures experimentally and the results were in good agreement with the numerical results by Li et al (1994). More recently, Fusina, Sislian & Parent (2005) studied the behaviour of standing oblique detonation waves near the Chapman-Jouguet (CJ) point of this structure.…”

“…The computation is carried out in the dashed zone, with the rotated coordinate system along the wedge surface. Previous results (Li et al 1994;Figueira da Silva & Deshaies 2000) demonstrate that the viscosity and boundary layer have little effect on this structure other than changing the boundary layer thickness slightly; and most of the research carried out before has been based on the inviscid assumption. Similarly in the present study, the non-dimensional Euler equations are used as the governing equations, given by…”

“…The structure proposed by Li et al (1994) has often been used in many subsequent investigations as the basis of the oblique detonation structure. However, it is possible to form another primary structure, where the OSW-ODW transition can be achieved smoothly.…”

“…Li, Kailasanath & Oran (1994) later simulated the oblique detonation and described the structure as composed of a non-reactive oblique shock, an induction region, a set of deflagration waves, and the oblique detonation surface. The transition of oblique shock wave to…”