QUANTITATIVE INVESTIGATION OF COMPRESSIBLE MIXING - STAGED TRANSVERSEINJECTION INTO MACH 2 FLOW

Planar measurements of the injectant mole fraction distribution and th e velocity field within a supersonic mixing flowfield have been made u sing laser-induced iodine fluorescence. The flowfield investigated in this work is staged transverse injection of air into a Mach 2 freestre am. A complete three-dimensional survey of the injectant mole fraction distribution has been generated, and a single planar velocity measure ment has been completed. The measurements reveal the dramatic effect o f streamwise vortices on the mixing in the near field of the injectors , as well as the rapid mixing generated by staging two fuel injectors. Analysis of the downstream decay of the maximum injectant mole fracti on in this and other supersonic mixing flowfields indicates that the r elative rate of injectant mixing well downstream of the injectors is i ndependent of injection geometry, freestream Mach number, and injectan t molecular weight. Mixing within this region or the flowfield is domi nated by small-scale turbulence within the injectant plume. The transi tion of the dominant mixing mechanism, from vortex-driven mixing in th e near field to small-scale turbulent mixing in the far field, was fou nd to occur in the region about 10 diameters downstream of the injecto rs.