Effects of polyurethane foam on the detonation propagation in stoichiometric hydrogen-air mixture

Abstract

The propagation of a detonation wave in a channel with polyurethane foam with different pore size on the wall was experimentally examined. In this study, we performed experiments in a rectangular channel with two walls covered with porous material to study the detonation suppression in stoichiometric hydrogen-air mixtures at room temperature and atmospheric pressure. Four types of polyurethane foam with a number of pores per inch (PPI) ranging from 10 to 80 covering two opposite channel walls were used for detonation attenuation. The width of the channel was 20 mm, the thickness of the porous layer was 10 mm. Piezoelectric pressure sensors were used to obtain the average velocity and shock wave pressure. The results indicate that depending on the pore size, two propagation regimes can be observed: steady detonation decay and detonation reinitiation. By the end of the porous section at 20 channel widths, the shock wave pressure was 0.5 of the von-Neumann pressure while using polyurethane with biggest pores (10 PPI) and 0.25 of the von-Neumann pressure in polyurethane with smallest pores (80 PPI). The evolution of the shock wave pressure and velocity along the porous section for porous material with different pore size is presented. Schlieren images of the detonation wave decay into a shock wave and the flame front in the section with polyurethane foam were obtained. The parameters of porous coatings are determined under which the detonation can be restored.