ON THE METHOD OF INDIRECTLY MEASURING GAS AND PARTICULATE PHASE VELOCITIES IN SHOCK-INDUCED DUSTY-GAS FLOWS

A method of indirectly measuring the temporally varying velocities of the gas and particulate phases in the nonequilibrium region of a shock wave moving at constant speed in a dusty-gas flow is described, and t his method is assessed by using experimental data from shock-induced a ir flows containing 40-mum-diameter glass beads in a dusty-gas shock-t ube facility featuring a large horizontal channel (19.7-cm by 7.6-cm i n cross-section). Simultaneous measurements of the shock-front speed w ith time-of-arrival gauges, particle concentration by light extinctiom etry and gas-particle mixture density by beta-ray absorption are used in conjunction with two mass conservation laws to obtain the indirect velocity measurements of both phases. A second indirect measurement of the gas-phase velocity is obtained when the gas pressure is simultane ously recorded along with the particle concentration and shock-front s peed when used in conjunction with the conservation of mixture momentu m. Direct measurements of the particulate-phase velocity by laser-Dopp ler velocimetry are also presented, as a means of assessing the indire ct velocity measurement method.