Optically efficient fluorescent tracers for multi-constituent PIV

This paper was motivated by the need for improved instrumentation to study mixing processes in multi-constituent and multi-phase fluid systems. The development of a single colour camera PIV system that can image micron size spectrally distinct fluorescent droplets in a multi-constituent gas phase flow is reported. Concentrations of fluorescent dyes in solution have been optimised to achieve sufficient fluorescence visibility. The adopted philosophy is to exploit the inherent co-registration offered by a 3-chip colour CCD camera with the images recorded in the three colour planes enabling flow constituent/phase to be determined as well as pulse order. The results show that the spectral discrimination process is robust and in a well mixed gas-phase flow the average error between the flow velocities in the two constituents is < 4%. The use of UV excitation (on suitably excitable dyes) has the added benefit of spectrally separating the excitation wavelength from the imaging bandwidth to allow 'flare removal'.