Experimental study on detonation-diffraction reflection point distances in hydrogen and gaseous hydrocarbon reactive systems

Abstract

In this study, the critical conditions of diffracted detonation waves expressed in terms of reflection point distances in Kawasaki and Kasahara (2020) were investigated for a wider range of fuel-oxidizer mixtures. In H2/O2, C2H2/O2, C2H4/O2, C2H6/O2, C3H6/O2, C2H6/N2O, and C3H6/N2O mixtures, these mixtures are used to measure the reflection point distance through the modification of the initial pressure and equivalence ratio of the mixture at room temperature. Moreover, the critical ideal reflection point distance divided by the channel width, which this dimensionless parameter was identified in the critical condition region of detonation diffraction. The results revealed that this region was in the range of 3.8 ± 0.8 for all investigated mixtures even though the equivalence ratio varied. The parameter lr,ip0 is the product of the ideal reflection point distance and the initial pressure, which is proportional to the energy (work) per unit area required for re-initiation. The larger the product of the reflection point distance and the initial pressure, the more difficult the mixture is to re-initiate, and the inverse of this parameter represents the ease of re-initiation, which can be considered an index of detonability. Detonability, which is the objective of clarification in this study, was found to have the order C2H2/O2 > C2H4/O2 > C3H6/O2 > C2H6/O2 > H2/O2 in the vicinity of the stoichiometric ratio, which is similar to the case using Matsui and Lee's critical initiation energy.