Effect of CO/H₂ ratio on detonation initiation characteristics of syngas/air mixture

This study aims to systematically characterize the effect of CO/H₂ molar ratio on the detonation initiation characteristics of syngas/air mixtures, identify the critical initiation threshold, and provide fuel optimization guidance for pulse detonation engines (PDEs), where short-distance/short-time detonation initiation is a core technical bottleneck. Numerical simulations were performed for 10 cases with CO/H₂ ratios ranging from pure CO to pure H₂ in a physical model simulating the detonation chamber of PDE, under consistent initial conditions (T=300K, p=1atm) and identical hot jet ignition parameters. The results showed that pure CO could not achieve direct detonation, while the addition of H₂ significantly enhanced the detonation sensitivity of the mixture, and the critical CO/H₂ molar ratio for successful detonation initiation lay in the range of 1.5 to 2. Three distinct detonation initiation modes were identified, and initiation time/distance showed non-monotonic variation with H₂ content. Detonation temperature and velocity decreased monotonically with falling H₂ proportion, while detonation pressure increased significantly at CO/H₂ ratios above 1:1.5. This study provides quantitative criteria for syngas composition optimization, facilitating the application of clean fuels and promoting the engineering implementation of PDEs.