Spontaneous initiation and development of hydrogen-oxygen detonation with ozone sensitization

The spontaneous initiation and sustenance of a detonation wave from a hot spot with a nonuniform initial temperature embedded within an H₂–O₂ mixture with and without O₃ addition were numerically investigated. For the case with either no or just a small amount of O₃ addition, a weak reaction wave was auto-ignited at the hot spot, accelerated, and then transitioned to a pulsating detonation, which propagated along the temperature gradient and quenched as it runs into the cold fresh mixture. However, with increasing O₃ addition, the possibility of sustenance of a developing detonation within the gradient was greatly enhanced as it enters the cold mixture. The reduced induction time by O₂ addition led to earlier appearance of the spontaneous reaction wave and detonation formation in the cold mixture, demonstrating that quenching of the detonation iss largely related to the instability property of the mixture due to the shortened induction time reduced significantly the instability. For 5% O₃ addition, a low-temperature flame produced by the O₃ reactions is present in front of the spontaneous reaction wave, inducing a local pressure wave, which facilitated spontaneous initiation and sustained the detonation entering the cold mixture. O₂ addition rendered the critical temperature to induce the minimum spontaneous wave speed higher than the crossover temperature, while they are very close for the case without O₃.