PLIF MEASUREMENTS IN AQUEOUS FLOWS USING THE ND-YAG LASER

This work identifies a new fluorescent tracer, 5(&6) carboxy-dichlorof luorescein, suitable for use with a Nd:YAG laser for quantitative PLIF concentration measurements in aqueous-phase flows. Fluorescence emiss ion calibrations are performed to validate the use of this laser/dye c ombination, and to reject other combinations examined. It is found tha t the commonly used sodium fluorescein dye has a non-linear signal res ponse when excited by the Nd:YAG laser, which makes this laser/dye com bination unsuitable for quantitative PLIF measurements, although it is acceptable for purely visualization purposes. The new proposed dye sh ows a linear response of fluorescent signal both with dye concentratio n and with laser intensity. Fluid-flow measurements taken with the Nd: YAG/carboxy-dichlorofluorescein system are found in agreement to meas urements obtained using a more standard laser/dye combination, namely Copper-vapor with sodium fluorescein, for which signal calibrations te sts are also presented.