Effects of inert-gas addition on the dynamic behavior and propagation characteristics of spherically expanding hydrogen-air flames
Toshiyuki KATSUMI,
Masashi KUMADA,
Haruki NOGUCHI
et al.
Abstract:To investigate the effects of inert-gas addition on the dynamic behavior and propagation characteristics of spherically expanding hydrogen-air flames, the experiments of premixed combustion were performed in a closed chamber. The dynamic behavior of premixed flames was caught by high-speed Schlieren imaging, and the flame radius and propagation velocity were measured by analyzing the Schlieren photography. When the flame radius was sufficiently small, smooth flame surface was observed, where the flame stretch … Show more
“…We handled hydrogen-methane-air lean mixtures and performed the combustion experiments in a closed chamber which was used in our previous study (Katsumi et al, 2023). The closed chamber had four quartz windows with diameter of 300 mm, and its inner volume was 73 L. The experimental system is shown in Fig.…”
In the hydrogen explosion at Fukushima Daiichi Nuclear Power Station, the presence of flammable organic compounds together with hydrogen in reactor buildings was suggested. Aiming to elucidate the explosion characteristics, we performed the experiments of spherically expanding hydrogen-methane-air lean premixed flames in a closed chamber, where methane was adopted as a representative of flammable organic compounds. At sufficiently small flame radii, smooth flame surface was observed. The addition of methane to hydrogen-air mixtures generated the increase in the propagation velocity of unstretched flame. At large flame radii, cellular surface induced by intrinsic instability was found, and the flame acceleration was confirmed. The parameters of flame acceleration model were estimated, and then the flame propagation velocity depending on the flame radius was predicted. The normalized increment coefficient became larger at low equivalence ratios, owing to stronger diffusive-thermal instability. Under the same hydrogen concentration, the methane addition generated the increase in the maximum pressure in a closed chamber. The maximum pressure of experiments was lower than that of calculations, which was because of heat loss during premixed combustion. Under the same methane concentration, the pressure ratio of experiments and calculations was lower when the flame propagation velocity was smaller. This was because of larger heat loss. The obtained results were valuable information to elucidate the hydrogen explosion at Fukushima Daiichi Nuclear Power Station.
“…We handled hydrogen-methane-air lean mixtures and performed the combustion experiments in a closed chamber which was used in our previous study (Katsumi et al, 2023). The closed chamber had four quartz windows with diameter of 300 mm, and its inner volume was 73 L. The experimental system is shown in Fig.…”
In the hydrogen explosion at Fukushima Daiichi Nuclear Power Station, the presence of flammable organic compounds together with hydrogen in reactor buildings was suggested. Aiming to elucidate the explosion characteristics, we performed the experiments of spherically expanding hydrogen-methane-air lean premixed flames in a closed chamber, where methane was adopted as a representative of flammable organic compounds. At sufficiently small flame radii, smooth flame surface was observed. The addition of methane to hydrogen-air mixtures generated the increase in the propagation velocity of unstretched flame. At large flame radii, cellular surface induced by intrinsic instability was found, and the flame acceleration was confirmed. The parameters of flame acceleration model were estimated, and then the flame propagation velocity depending on the flame radius was predicted. The normalized increment coefficient became larger at low equivalence ratios, owing to stronger diffusive-thermal instability. Under the same hydrogen concentration, the methane addition generated the increase in the maximum pressure in a closed chamber. The maximum pressure of experiments was lower than that of calculations, which was because of heat loss during premixed combustion. Under the same methane concentration, the pressure ratio of experiments and calculations was lower when the flame propagation velocity was smaller. This was because of larger heat loss. The obtained results were valuable information to elucidate the hydrogen explosion at Fukushima Daiichi Nuclear Power Station.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.