Experimental study of the combined effects of CO2 and obstacles on the explosive behavior of syngas

This article experimentally investigates the explosion behaviors of syngas, focusing on the combined effects of obstacles and CO₂ on flame front evolution, flame front velocity (FFV), overpressure, and maximum overpressure (P_max). Results demonstrate that CO₂ prolongs the flame propagation time, with increasing concentration delaying the onset time of the tulip flame (t_tulip). A secondary tulip phenomenon is observed at α(H₂) = 30 % and α(CO₂) = 20 %. For pipes with obstacles, increasing CO₂ concentration reduces the impact of the obstacles on flame propagation, slows the flame front velocity, and causes the flame front to exhibit different shapes after passing through the obstacle. As α(H₂) increases, the overpressure also rises substantially, with P_max increasing up to 3.74 times compared to the scenario without obstacles. When α(CO₂) reaches 15 %–20 %, the P_max without obstacles surpasses that with obstacles, suggesting that at higher α(CO₂), the obstacles have a minimal impact on the gas explosion, with α(CO₂) becoming the dominant factor.