Mixing Characteristics for Flush and Elevated Jets in Crossflow

The present experiments explore the mixing and structural characteristics of equidensity and variable density gas-phase transverse jets using acetone PLIF as well as stereo PIV. Flush and elevated nozzles as well as a flush pipe geometry are explored in these studies, for a range of jet-to-crossflow momentum flux ratios $J$ and density ratios $S$, spanning previously-determined conditions creating upstream shear layers which are either convectively unstable or absolutely unstable. The present studies quantify a range of mixing and flow metrics for the jet in crossflow, including conditional unmixedness, conditional probability density function, and scalar dissipation rates associated with both the jet cross-section and the centerplane longitudinal imaging. Correlations between mixing parameters and the structural symmetry/asymmetry in the JICF are observed, as are connections with the state of the shear layer and vorticity evolution.