Study on Initiation Characteristics of Oblique Detonation Induced by Hydrogen Jets in Acetylene-Air Mixtures

In this paper, effects of hydrogen jets on the initiation characteristics of oblique detonation wave (ODW) are investigated, the two-dimensional (2D) multi-component NS equations considering chemical reactions are solved. Influences of the transverse jet on flow field characteristics of the ODW are studied, including the initiation characteristics, the wave structures, and the state parameters. The existence of the jet changes the ignited mode of the ODW from double Mach interaction to single Mach interaction. Several wave configurations and their transitions induced by the jets are observed, including the classic deflagration-to-ODW transition, jet-induced oblique shock wave (OSW) in front of the transverse jet and rapidly develops into ODW, and ODW that generated directly in front of the transverse jet. Two types of relationships are obtained between the detonation distance and the position of the transverse jet: the U-shaped curve at low flow discharge and the positive correlation at high flow discharge. Furthermore, the viscous effect has significant influence on the flow field characteristics of ODW, it promotes the transition between these initiation modes and shortens the initiation distance of oblique detonation.