Particle Image Velocimetry Measurements during Shock Wave Interactions with Dense Particle Fields

Recently, experiments in the Multiphase Shock Tube (MST) have provided rare data for the interaction of a planar shock wave with a dense field of particles [1]. The MST (Fig. 1) is used to drive a planar shock wave into a dense ‘particle curtain’ of 100-micron glass spheres having an initial volume fraction of about 20%, which is formed with a gravity-fed seeding apparatus. High-speed imaging and pressure measurements have shown that following the impingement of the incident shock, the particle curtain propagates downstream while spreading rapidly. The data suggested the expansion of the particle curtain to be associated with a difference in particle drag across the streamwise thickness of the particle field. Through new drag models validated with MST data, Ling et al. [2] have demonstrated that dense particle distributions lead to a significant increase in interphase momentum transfer and a prolonged flow unsteadiness.

The understanding of compressible dense gas-solid flows has been improved over the last few years, though a better understanding of the particle dispersal necessitates measurements of the surrounding gas. Shock-particle interactions are highly unsteady owing to reflected and transmitted shock waves (Fig. 2). Additionally, downstream-propagating compressions and upstream-propagating expansions occur to equilibrate the pressure across the curtain [1, 2]. Quantifying these unsteady processes requires gas velocimetry data. Similar to other shock tube studies [e.g., 3], PIV is used here (Fig. 3), in this case to measure the unsteady velocity fields associated with shock-particle interactions. Such data will be used to provide a metric of the unsteady interphase momentum transfer.

1. Wagner, J. L., Beresh, S. J., Kearney, S. P., Trott, W. M., Castaneda, J. N.., Pruett, B. O., Baer, M. R. (2012) A Multiphase Tube for Shock Wave Interactions with Dense Particle Fields, Experiments in Fluids, Vol. 52: 1507-1517.
2. Ling, Wagner, J. L., Beresh, S. J., Kearney, S. P., S. Balachandar. (2012) Interaction of a Planar Shock with a Dense Particle Curtain, Physics of Fluids, Vol. 24; 113301
3. Balakumar, B. J., Orlicz, G.C., Tompkins, C. D., Prestridge, K. P.., (2008) Simultaneous particle-image velocimetry-planar laser-induced fluorescence measurements of Richtmyer-Meshkov instability growth in a gas curtain with and without reshock, Physics of Fluids, Vol. 20: 124103.