Study on the deflagration characteristics of hydrogen-rich methane and key radical reaction kinetics

Abstract

In order to ensure the safe use of hydrogen / methane fuels, the flame characteristics, explosion pressure flame stability, laminar burning speed and OH radical changes in the lean, stoichiometric and rich mixture are investigated systematically by varying hydrogen addition which were studied in a 20L spherical explosive vessel. The results show that the pressure changes slowly with time under oxygen-rich conditions and violently under equivalent and oxygen-poor conditions. When the hydrogen addition is more than 50 %, the explosive destructive power increases sharply, and this phenomenon does not change with the change of the equivalent ratio of the mixed fuel. The appearance of flame cellular structure is closely related to the equivalent ratio and hydrogen addition ratio of hydrogen/methane premixed gas. Experimental results show that hydrogen/methane premixed fuels are more likely to produce cellular structure flames under oxygen-enriched conditions and at higher hydrogen addition ratios. The hydrogen addition ratio in the hydrogen/methane premixed gas dominates the flame propagation, while the equivalence ratio Φ plays a secondary role. In terms of Markstein length, the flame development of hydrogen/methane premixed gas is stable under oxygen-poor conditions; under oxygen-rich and equivalent conditions, the flame orientation tends to be unstable when the hydrogen addition ratio of hydrogen/methane premixed gas is less than 50 %, while the flame orientation tends to be stable when the hydrogen addition ratio is greater than 50 %. The laminar flame propagation velocity calculated by the experiment in this paper is consistent with the laminar flow velocity of the hydrogen/methane premixed gas calculated by GRI Mech 3.0. The time for the OH to reach the voltage peak signal freely and the time for the explosion pressure rise rate of the hydrogen/methane premixed gas to reach the peak time are consistent when the hydrogen addition ratio is more than 50 %.