Relative evaporation rates of droplets in a segmented stream determined by droplet-cavity fluorescence peak shifts

摘要

Abstract: porated gas behind each flowing droplet affects the evaporation rate and drag of trailing droplets. For interacting droplets, we present a diagnostic technique that is capable of measuring evaporation-related droplet radius changes and drag- related flow velocity changes. When irradiated by a pump-laser beam, each dye-containing droplet acts as a laser, emitting at discrete wavelengths that correspond to morphology-dependent resonances of a sphere. Small wavelength shifts in the lasing spectra from each droplet are related to its radius change and hence, the decrease of the droplet volume. For an isolated droplet-stream segment, the evaporation rates of trailing droplets behind a lead droplet are determined.!10