Study on hydrogen-air explosion flameless venting with metal foam addition

Abstract

This study elucidates the effects of metal foam on the hydrogen-air explosion venting process through experiments with hydrogen concentrations ranging from 14.38 to 29.58 %. The introduction of metal foam significantly alters the vented flame morphology, forming a mushroom cloud due to momentum convection. Increasing metal foam thickness systematically reduces the vented flame scale, with complete quenching observed at 100 mm thickness at the stoichiometric ratio. And the energy distribution within the metal foam is analyzed based on the cold wall effect. The analysis reveals a substantial rise in internal chamber pressure, escalating from 235.78 kPa in ordinary explosion venting scenarios to 612.15 kPa when utilizing 100 mm of metal foam at the stoichiometric ratio. A predictive model integrating explosion venting theory and metal foam's flow resistance characteristics is developed to understand the relationship between foam thickness and maximum reduced pressure. The flameless venting efficiencies are computed based on the model, showing approximately 70 % at an equivalence ratio of 0.4 and 15 % at the stoichiometric ratio, demonstrating that diminishing the combustion velocity could effectively elevate the flameless venting efficiency.