Role of temperature-gradient steepness on development of hydrogen-oxygen detonation with ozone sensitization

This work carries out one-dimensional simulations on spontaneous initiation and development of detonations from hot spots with initial temperature gradients embedded with non-autoignitive H₂–O₂ mixtures. Role of temperature-gradient steepness on the development of detonations inside and outside hot spots and the relationship of it to ozone sensitization are examined by changing gradient slope and O₃ addition. It is found that steepening temperature gradient has negative effect on initiations and a critical gradient is identified for different O₃ additions, below which spontaneous initiation fails. However, the sustenance of a developing detonation is not only related to the steepness, but also to the reactivity of mixtures with O₃ additions. High O₃ additions permit a detonation to be more likely to sustain outside hot spots; while for low O₃ additions, the sustenance depends nonmonotonically on the slope, which cannot be predicted by the idealized reactive flow system with a constant specific heat ratio and the reduced reaction model. The results clarify the suggestions of He & Clavin [1] that temperature gradient may prevent sustenance of a developing detonation and the transmission of detonation to the uniform fresh mixture.