Simultaneous Whole-Field Measurements of Velocity and Concentration Fields Using Combined MTV and LIF

摘要

A new technique is described for the simultaneous measurement of velocity and concentration fields. We describe here applications in liquid-phase flows, but the methodology can be extended to gas-phase flows with appropriate tracers. In this single-laser, two-tracer approach, molecular tagging velocimetry (MTV) based on a phosphorescent compound is combined with laser induced fluorescence (LIF) using fluorescein as tracer. Results show that one can design experiments with minimal cross-talk between the LIF and MTV signals. Application of the simultaneous MTV-LIF technique is demonstrated by performing simultaneous flow visualization and vorticity measurements in a low Reynolds number forced wake and simultaneous velocity-concentration measurements in a turbulent mixing layer. Preliminary data are presented on the mean and rms fluctuation of velocity and concentration, along with the correlation between velocity and concentration fluctuations.