Explosion behaviors of hydrogen-nitrous oxide mixtures at reduced initial pressures

Abstract

In this study, we report the explosion characteristics of H2/N2O mixtures at fuel-lean side and stoichiometric condition in a 113 L cylindrical vessel. Experiments were performed at different sub-atmospherical pressures (P0 =10 kPa–40 kPa). Explosion pressure traces were obtained by a pressure transducer mounted on the wall. Meanwhile, the flame morphology was recorded using schlieren visualization. The maximum explosion pressure (Pmax) and maximum pressure rise rate ((dp/dt)max) were derived and discussed. Results show that two competitive effects (i.e., the adiabatic flame temperature and the molecular number) make the maximum Pmax occurring at φ =0.5—0.6. Linear correlations were found between Pmax and P0. Except the adiabatic flame temperature and flame propagation speed, the flame instability was found to participate in dominating the maximum pressure rise rate. For increased initial pressure, the equivalence ratio of the maximum (dp/dt)max switches to the lean side due to the enhanced flame instability. Depending on different equivalence ratios, both linear and quadratic correlations were found between (dp/dt)max and P0.