Detonation structure of C2H4-O-2-Ar mixtures at elevated initial temperature

The influence of initial pressure and temperature on the detonation structu re of stoichiometric ethylene-oxygen-argon mixtures was studied. The detona tion tube (53 mm i.d. and 7.2 m long) was electrically heated by Joule effe ct 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 incre ases with the initial temperature in the range of 300-600 K. The detonation cell size data were correlated with the chemical induction length calculat ed 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/RTZND similar or equal to 5), the detonation cel l 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 w hen increasing initial temperature.