GAS FILTRATION DURING THE IMPACT OF WEAK SHOCK-WAVES ON GRANULAR LAYERS

This paper deals with the unsteady gas filtration through a granular l ayer attached to a rigid end-wall when impacted head-on by a weak shoc k wave in a shock tube. The main goal of the present work is to study the gas pressure field developed inside the granular layer during its compression by the shock wave. A physical model is proposed for simula ting the phenomenon and solved numerically. The numerical results are compared with the measured gas pressure at different locations inside the sample and at the end-wall covered by the granular layers. Good ag reement is found between the calculated gas pressure signals and those measured at the shock tube end-wall covered by a granular layer at th e final stage when the gas pressure is mostly governed by gas filtrati on. In the initial, unsteady part of the signals, large deviations exi st between the calculated and the experimental results. The only reaso n for the agreement or discrepancy between the theoretical predictions and the experiments is the compaction effect associated with the form ation of the gas pressure profile at the shock tube end-wall covered w ith a granular layer. (C) 1997 Elsevier Science Ltd.