Numerical study on the effects of chemical kinetics models on initiation structure of oblique detonation waves

The initiation of wedge-stabilized oblique detonation waves (ODW) has garnered significant attention in recent years. However, many prior studies relied on simplified chemical kinetics without thorough comparative evaluation against detailed mechanisms, leaving uncertainties about their ability to accurately capture critical aspects of ODW initiation. To address this limitation, this work conducts a comprehensive comparative study to investigate the impact of chemical kinetics on ODW initiation. Simulations of supersonic, premixed, stoichiometric ethylene-air flow over a wedge were performed to analyze the effects of different chemical mechanisms on ODW initiation. The results reveal that ODW development is strongly influenced by the induction time and exothermic rate of the chemical reactions, while the Chapman–Jouguet (C-J) speeds and ODW angles remain consistent across mechanisms. Among the mechanisms tested, at an altitude of 30 km, the 57-species mechanism predicted an induction length of about 8.3 mm and a reaction zone length of 6.2 mm, whereas the 10-species mechanism gave much larger values of 19.8 mm and 95.8 mm, respectively. Similarly, the ignition delay time of the 10-species mechanism was nearly six times longer, with a peak exothermic rate about two orders of magnitude lower than that of the detailed mechanisms. The findings demonstrate that intermediate-radical chemistry plays a critical role in governing ODW development and that detailed mechanisms are required for accurate modeling of hydrocarbon-fueled ODWs. This study provides new quantitative insight into chemical-kinetic sensitivity and offers guidance for mechanism selection in high-speed combustion and detonation modeling.