Theoretical Prediction Model of Critical Energy for Direct Detonation Initiation in H2-O2/Air Mixtures

Based on the critical tube diameter and detonation cell size data in H2-O2/Air mixtures, the piston work done model was used to predict their critical energies of direct initiation. The good agreement is found by comparing the theoretical predicted critical energies with those measured in the experiment. Thus, the theoretical model is proved to be able to predict the critical energy of H2-O2/Air mixtures within satisfactory. From the theoretical prediction model, it is obviously shown that the critical energy for H2-Air is significantly bigger than H2-O2 mixture when at the same initial conditions. The ZND induction zone length was further investigated to study the large critical energy discrepancy behavior between those mixtures, the results clearly indicated that the induction zone length for H2-Air is much longer than that of H2-O2 mixture at the same initial condition, and it is cube relationship between critical energy and induction zone length, which results in the bigger critical energy of the H2-Air mixture. This result is in agreement with the critical energy predicted from theoretical model.