Detonation characteristics of H2-air diluted with N2 in smooth tube

In the process of severe accidents, the core melts and the chemical reaction between the Zr and steam cause the production of hydrogen. The hydrogen will flow into the containment through the break of the primary circuit boundary. If the hydrogen concentration in the local space reaches to the detonation limit, the explosion may happen. The pressure and temperature loads caused by hydrogen detonation will threaten the integrity of the containment. This study was performed to analyses the detonation characteristics on the influence of the hydrogen concentration, dilute gas concentration and initial pressure. The results show that the detonation cell size became smaller and more irregular when the hydrogen concentration of mixed composition get close to theoretical ratio, it indicated that the detonation is very violent and unstable; when using nitrogen to dilute hydrogen oxygen mixed gases, the detonation limits decreases significantly while the velocity reduction increased; Hydrogen detonation gradually stabilized when the initial pressure was reduced and the velocity reduction increases together, the dilution of inert gas would aggravate this phenomenon, This suggests the detonation in low initial pressure or low hydrogen concentration extinguished easily.