Author(s)

KATHY PRESTRIDGE

Abstract

Experiments of shock-accelerated microparticles show high drag coefficients when the particles are tracked from initial acceleration through the relaxation times. An eight-pulse particle tracking diagnostic measures individual particle positions, and a schlieren 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 for Mach 1.2, 1.3 and 1.4 experiments, allowing us to calculate accelerations and drag. Findings show that early-time drag is underestimated by current quasi- steady drag models due to several factors. The exact physical mechanisms causing the large drag are likely due to body pressure forces caused by the particle wake disturbing the carrier phase.

Keywords

unsteady drag, microparticles, shocks, shock tube