Detonation structure of C $_2$ H $_4$ -O $_2$ -Ar mixtures at elevated initial temperature

Abstract

The influence of initial pressure and temperature on the detonation structure of stoichiometric ethylene-oxygen-argon mixtures was studied. The detonation tube (53 mm i.d. and 7.2 m long) was electrically heated by Joule effect at a rate of about 100 K per minute. For initial pressures ranging from 0.1 to 1 bar, experimental results show that the detonation cell size increases with the initial temperature in the range of 300–600 K. The detonation cell size data were correlated with the chemical induction length calculated using the ZND model for the detonation wave and global chemical reaction kinetics. Due to the low value of the reduced global activation energy of the chemical kinetics $(E_a/{R{{\rm T}_{ZND}}} \simeq 5)$ , the detonation cell size varies inversely with the initial density. Assuming that at elevated initial temperature the classical detonability criteria based on cell size are still valid, we find that the detonability of this mixture decreases when increasing initial temperature.