Concentration/velocity measurements in the mixing layer of two plane streams

The dynamics of quasi-ordered structures in plane mixing layers has been investigated using a two-stream wind tunnel specially designed and built for this study. Instantaneous concentrations of passive contaminants were measured in real time using a scattering technique; the velocity field was measured by using laser Doppler anemometry simultaneously with hot-wire anemometry. Conditional sampling and phase averaging were applied to flow visualization by using a stroboscopic technique. An analysis of experimental results shows that many effects characteristic of turbulence, such as enhanced transport rates of momentum and mass, are strongly influenced, if not fully controlled, by the interactions between the quasi-ordered structures.