Revisiting the unsteady drag of shock-accelerated solid particles

Previously published results from the Horizontal Shock Tube (HST) facility at Los Alamos National Laboratory showed unsteady drag an order of magnitude above the standard drag curve. However, forensic investigation of these results showed evidence that a faulty assumption of the particle size during processing of the data led to this result rather than new physics. To confirm the results of the forensic investigation, new experimental data is needed. In this presentation, the previous experiments are re-created but with a tightly controlled diameter. The experiment involves solid Nylon particles nominally 4 μm in diameter in dilute suspensions subject to shocks of Mach 1.2, 1.3, and 1.4. An eight-pulse particle tracking diagnostic measures individual particle positions, and a shadowgraph system measures shock location, with pressure transducers providing shock speed at the test section. These diagnostics give us detailed measurements of particle positions versus time. From the particle positions, empirical fits are performed to determine the unsteady particle drag. The newly obtained data with the tightly constrained particle diameters will be compared with the previously published data.