Characterization of Water Mist Sprays Using a Phase-Doppler-Particle-Analyzer and an Iso-Kinetic Sampling Probe

Abstract

A Phase-Doppler-Particle-Analyzer (PDPA) was used to screen candidate water mist nozzles for use in a scaling validation aimed to allow scaled-down testing of water mist systems. A custom-designed iso-kinetic sampling probe (IKSP) was developed to independently measure water mist fluxes at the same locations where PDPA measurements were made. Measurements were taken at two elevations in selected full-cone water mist sprays. The water drop size was found to increase with radial distance from the spray centerline, while the mean drop velocity and drop concentration decrease with radial distance. Gross drop size distributions of water mist sprays were derived from local drop size distributions and water fluxes measured in two spray cross sections. It was found that, for the water mist sprays investigated in this study, both Rosin-Rammler and log-normal distributions are required to correlate the entire drop size spectrum. In general, the agreement between the mist fluxes measured with the PDPA and iso-kinetic sampling was within 7% near the spray centerline. The selected nozzles show appropriate intended scaling in terms of the drop size, nozzle discharge pressure, and water discharge rate.