Particle image velocimetry (PIV) is a valuable technique to characterize surface interaction with fluid flows. Reliable seed materials are requisite to accurately determine flow properties using PIV. In particular, low density will reduce the lag time, the delay of a seed particle reaction to changes in the flow, and a narrow size distribution will reduce the measurement uncertainty. Polystyrene latex microspheres (PSL)s have these properties. We are developing multifunctional PSLs to characterize multiple parameters of fluid flow with a single seed material. PSLs doped with a variety of fluorescent dyes were generated by dispersion polymerization. These seed materials may enable 'near wall' measurements unobtainable using state-of-the-art seed materials. The dye-doped particles were spectroscopically characterized both dispersed in solution and in the dry state (conditions used during PIV experiments). PSL size distributions were determined using dynamic light scattering and microscopic techniques. PSLs were doped with several fluorescent dyes with temperature sensitivity and the fluorescent emission temperature dependence was evaluated. PSL glass transition temperature was determined to be 105 �C using differential scanning calorimetry. For dye-doped PSLs evaluated in the dry state, the fluorescent emission spectral shape and intensity changed upon increasing temperature from 30 to 100 �C when excited at 532 nm. Preliminary measurements completed using dye-doped PSLs in air flows of known temperature indicating that the detection emission may be sensitive enough to discern both velocity and temperature. 

Fluorescent dye-doped polystyrene microspheres for particle image velocimetry

246th National Meeting (2013)

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