Interactive effect of shock wave with porous foam

Abstract

Collision of a planar shock wave with porous foam is investigated experimentally by holography as well as numerically. We investigate the unsteady process occurring when a shock wave passes through porous material. Experiments on shock wave-foam interaction are conducted by using a shock tube. Experimental form of polyurethane foam is of 60mm X 150mm cross section with 1200mm long (open cell type, high-porosity &=0.974 0.987 and low density pc=16-31kglm3). The deformation and wave propagation in the foam is visualized by using single-exposure holographic interferometry and high speed video. The compression wave in the foam moves at lower velocity than the shock wave (Ms=1.19). When the incident shock wave hits a foam surface, part of the shocked gas penetrates into the foam and interacts with the foam skeletons, and the foam begins to move towards the end wall. The leading edge of the foam is compressed by the incident shock pressure and wall friction. Numerical simulations are compared with the shock tube experiments, which show essentially same stress variations with experimental results.