Influence of elementary reactions on the propagation mechanism of multicomponent gas-phase detonation

Cracking technology is a key technique for enhancing the combustion efficiency of liquid kerosene used in aerospace engines. Despite extensive exploration of cracking technology, the detonation characteristics of cracked gas remain poorly understood. Herein, detonation experiments were conducted in a smooth tube using various fuel mixtures: multi-hydrogen cracked gas–O2 mixtures, poor-hydrogen cracked gas–O2 mixtures, H2–O2 mixtures and CH4–O2 mixtures. The initial pressure ranged from 20 to 100 kPa. The findings indicate that the velocity of multi-hydrogen cracked gas consistently exceeds 0.95 VCJ, irrespective of the initial pressure, whereas the velocity of poor-hydrogen cracked gas is considerably influenced by the initial pressure. Analysis conducted on the Cantera platform elucidated this phenomenon from the perspective of chemical reaction kinetics, revealing that hydrogen predominates in the competitive reaction against methane. Cellular structures were captured using smoked foils. Smoked foils revealed that with an initial pressure exceeding 80 kPa, the detonation wave of the multi-hydrogen cracked gas transitioned into an overdriven state. Conversely, the detonation wave of poor-hydrogen cracked gas remained in a self-sustaining stable state at distances ranging from 3200 to 3600 mm throughout the observation period. In addition, the ratio of cell sizes between multi-hydrogen cracked gas and poor-hydrogenation gas was consistently maintained at 68 %. The hydrogen content in the cracked gas was found to influence the gradient of cell size variation with the initial pressure. Our research addresses the knowledge gap in the propagation mechanisms of cracked gas detonation and lays a theoretical basis for improving fuel propulsion in aerospace engines.