Drop/Gas Interactions in Dense Sprays

This is a final report of research considering three types of drop/gas interactions that are important. in the near-injector, dense region of sprays, namely: (1) secondary drop breakup, which is an intrinsic outcome of primary breakup and is the most significant rate process of dense sprays; (2) turbulence generation by dispersed phases, which is the most significant source of turbulence production within dense sprays; and (3) the structure of sphere wakes at moderate Reynolds numbers, which is a fundamental property needed to understand turbulence generation. The properties of secondary breakup were observed for shock wave initiated disturbances in air at normal temperature and pressure, using pulsed shadowgraphy and holography to measure the dynamics and outcome of breakup and theories phenomenological theories to interpret and correlate the measurements. Particle-generated turbulence was observed using uniform fluxes of spherical particles falling through (in the mean) air, using phase-discriminating laser velocimetry to measure flow properties and stochastic analysis to interpret and correlate the measurements. The properties of sphere wakes at moderate Reynolds numbers were observed in both nonturbulent and turbulent environments, using laser velocimetry to measure flow properties and similarity theories to interpret and correlate the results.