Evolution of detonation wave and parameters of its attenuation when passing along a porous coating

Usually, attenuation of a shock or detonation wave at a normal or tangential impact to the surface of technological structures can be carried out using porous coatings. In the present work the processes of decay of a detonation wave in a hydrogen-air mixture during propagation along a porous surface were considered. We investigated how the replacement of the porous layer on the inner walls of the channel can affect the amplitude of a shock wave and the impulse of pressure generated by the passing detonation wave. We have shown how a shape of the flame front and the porous surface changes, and how these can affect the pressure beneath the porous layer. As characteristic materials, we considered porous materials with open pores (polyurethane foam, steel wool) and also with a gas-impermeable tape. Propagation and evolution of the shock wave and flame front were investigated in a rectangular cross-section channel, with a porous polyurethane, polypropylene tape or steel wool coating. Experiments were carried out in a hydrogen-air mixture undiluted by inert gas at atmospheric pressure. A stationary detonation wave was formed before entering the section with the porous walls. The dynamics of the flame front and shock waves were registered using a high-sensitivity digital camera and a Schlieren system. Pressure beneath the porous coating was measured by piezoelectric pressure transducers.