Detonation suppression in hydrogen–air mixtures using porous coatings on the walls

We considered the problem of detonation suppression and weakening of blast wave effects occurring during the combustion of hydrogen–air mixtures in confined spaces. The gasdynamic processes during combustion of hydrogen, an alternative environmentally friendly fuel, were also considered. Detonation decay and flame propagation in hydrogen–air mixtures were experimentally investigated in rectangular cross-section channels with solid walls and two types of porous coatings: steel wool and polyurethane foam. Shock wave pressure dynamics inside the section with porous coating were studied using pressure sensors; flame front propagation was studied using photodiodes and high-speed camera visualization. For all mixtures, the detonation wave formed before entering the section with porous coating. For both porous materials, the steady detonation wave decoupled in the porous section of the channel into a shock wave and flame front propagating with a velocity around the Chapman–Jouguet acoustic velocity. By the end of the porous section, shock wave pressure reductions of 70 and 85% were achieved for the polyurethane foam and steel wool, respectively. The dependence of the flame velocity on the mixture composition (equivalence ratio) is presented.