A simultaneous planar Rayleigh scattering and planar laser-induced fluorescence (PLIF) technique yields planar measurements of the full three-dimensional scalar dissipation rate field, χ≡DΔC·ΔC, in gas-phase planar turbulent jets. The jet consists of propane, seeded with acetone, issuing into air. The propane serves as the primary Rayleigh scattering medium, with the acetone being used for fluorescence. Results for the scalar dissipation rate are shown for jet outer scale Reynolds numbers Re{sub}δ ranging from 3200 to 8400. From these results, an estimate for the magnitude of the finest mixing scale is presented, and the (Re{sub}δ){sup}3/4 scaling of the dissipation length scales is verified. The decay of average scalar dissipation rate with downstream distance is shown to be slower than predicted by existing models for the evolution of scalar dissipation.
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