Effect of ignition position and inert gas on hydrogen/air explosions

• Published in: International journal of hydrogen energy 2021-02, Vol.46 (12), p.8820-8833
• Main Authors: Yang, Wen, Zheng, Ligang, Wang, Chengzhe, Wang, Xi, Jin, Hongwang, Fu, Yuanpeng
• Format: Article
• Language: English
• Subjects: Dilution; Flame instabilities; Hydrogen explosion; Laminar burning velocity; Pressure oscillations
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2020.12.078

The effects of inert gas (i.e., He, Ar, and N2) and ignition position on flame dynamics in a half-open duct with an aspect-ratio of 10 are analyzed for hydrogen/air mixtures with constant laminar burning velocity SL. The results indicate that hydrodynamic and thermo-diffusive instabilities dominate flame propagations with ignition at the right-half part of the duct, while Rayleigh–Taylor instability dominates with ignition at the left-half part of the duct. The flame-sound interaction results in the periodic pressure oscillations. Due to decreased instability, the He-diluted flame exhibits a weaker sensitivity of explosion parameters to the ignition position. The maximum pressure Pmax is dominated by different mechanisms depending on the ignition position. Although constant SL is used, Pmax for the worst case with N2 dilution is two times that with He dilution, demonstrating the considerable effect of flame instabilities. Finally, a chemical kinetic calculation is performed to clarify the flame stabilities. •Effects of ignition position and dilution on hydrogen/air explosion are studied.•Ar- and N2-diluted mixtures show stronger instability than He-diluted mixtures.•Flame-sound interaction affects the oscillatory pressure via RT instability.•Max. pressure for He-diluted mixtures shows weaker dependence on ignition position.•Key free radicals such as H/O/OH are of great significance to flame instability.