A quantitative mixing analysis using fluorescent dyes

Abstract

A method of quantifying fluid mixing using the fluorescence intensity of fluorophors in aqueous solution is presented. The general technique involves ratioing optically separable fluorescence from two fluorescent dyes. The resulting ratio normalizes for laser intensity distribution and any laser reflections. By properly selecting the fluorescent dyes, fluorescence ratios can be used to either measure the concentration of a passive scalar or temperature fields. In this study, fluorescence ratios were used to quantify the hydronium ion concentration of mixing fluids in a 2D plane. This was accomplished by temporally and spatially synchronizing two CCD cameras to simultaneously image laser induced fluorescence. Single and multidye systems were examined for their accuracy in predicting mixing; of the dye systems examined, a fluorescent rhodamine B solution proved to be the most accurate. Using this dye system, the fluorescence ratios were found to vary under 1 standard deviation for a 2.5 fold change in laser power. A standard error of under 6 percent of the mean fluorescence ratio was typical. (Author)