Facilitated ignition and detonation initiation of hydrogen-oxygen mixtures by ozone doping

Haiyue Li, Wenkai Liang, Chung K. Law

Research output: Contribution to journalArticlepeer-review

Abstract

This work computationally studies homogeneous and inhomogeneous ozone addition in hydrogen-oxygen ignition and transition to detonation, with emphasis on the ozone-induced two-stage behaviors in the chemical kinetics and wave dynamics. In 0D homogenous ignitions, ozone addition induces an additional first-stage reaction and substantially reduces the ignition delay time (IDT). At intermediate initial temperatures, e.g. T0 = 600 K, a critical value, αcr, is identified to delineate different regimes for ozone fraction in the total oxidizer, α. Specifically, the first-stage ignition occurs several orders earlier than IDT for α<αcr, while the IDTs for two stages are comparable for α>αcr. Mechanistically, low-to-intermediate temperature HO2 chemistry introduces a quasi-steady intermediate state in the former regime, whereas ozone reactions directly accelerate high-temperature H2–O2 reactions in the latter one. Furthermore, according to the Zel'dovich mechanism, ozone concentration non-uniformity can establish reactivity gradient and hence further initiate double spontaneous waves with multiple dynamics. Coherent coupling between the second-stage heat release and pressure (shock) wave can further evolve into detonation, whereas such synchronized enhancement is not observed in the first-stage ignition due to its large excitation time. Corresponding to the multi-timescales in 0D ignition, when the initial α interval are respectively below, across and above αcr, the low- and high- temperature reaction fronts always separate, first separate then merge, and always merge, respectively. It is also noted that at higher initial temperatures αcr decreases, and that the first-stage reaction becomes less concentrated. Consequently, detonation can be initiated with smaller amounts of ozone and is minimally influenced by the first-stage reaction.

Original languageEnglish (US)
Article number112474
JournalCombustion and Flame
Volume246
DOIs
StatePublished - Dec 2022

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Physics and Astronomy(all)

Keywords

  • Ignition delay time
  • Ozone chemistry
  • Spontaneous detonation initiation
  • Two-stage behavior

Fingerprint

Dive into the research topics of 'Facilitated ignition and detonation initiation of hydrogen-oxygen mixtures by ozone doping'. Together they form a unique fingerprint.

Cite this