Experimental Study on the Effects of Suppression Gases on Wave System Evolution and Flame Development in Hydrogen-Blended Natural Gas Deflagration

Hydrogen-blended natural gas (HBNG) is considered a promising low-carbon fuel, while hydrogen addition may increase explosion hazards by accelerating flame propagation and pressure development. In this study, a diaphragm-coupled experimental system was employed to investigate the effects of hydrogen blending ratio, the type of gas in the driven section, and initial CO2 pressure on the coupled propagation characteristics of pressure waves and flame fronts in HBNG explosions. Synchronized pressure measurements, flame detection, and schlieren visualization were used to analyze wave-flame evolution during propagation. The results showed that increasing the hydrogen blending ratio from 0% to 30% increased the average flame velocity in the driver section from 20.8 m/s to 29.4 m/s and reduced the diaphragm rupture time from 153 ms to 105 ms. The type of gas in the driven section significantly affected the diaphragm rupture time and downstream wave-flame propagation. Among the investigated gases, CO2 exhibited the strongest suppression effect, increasing the diaphragm rupture time from 105 ms to 138 ms and reducing the maximum overpressure at P6 by approximately 37%. Increasing the initial CO2 pressure from 101.33 kPa to 162.12 kPa further reduced the maximum overpressure from 624 kPa to 344 kPa and delayed flame arrival at F3 from 149 ms to 415 ms. The suppression effect became increasingly pronounced with propagation distance, indicating progressive attenuation of the pressure wave and an increasing delay in flame propagation with distance. These findings highlight the important influence of downstream gas properties on wave-flame evolution and demonstrate the potential of pressurized CO2 for suppressing hydrogen‑blended natural gas explosions in diaphragm-coupled systems.