Experimental Characterization of Sprays in a Recessed Gas-Centered Swirl Coaxial Atomizer

Abstract

The characteristics of sprays from a recessed gas-centered swirl coaxial atomizer (RGCSCA) with gas to liquid momentum flux ratio, J of the spray in the range of 2–66 are studied experimentally through the analysis of spray morphologies and droplets characteristics. The process of fully developed spray (spray free from ligaments/droplets clusters and nonspherical droplets) in the atomizer is quantified. In the RGCSCA, the distance from the atomizer exit to the fully developed spray zone decreases with increase in J. Detailed measurements of size (in the range of 6–378 μm) and velocity (in the range of 35–176 m/s) characteristics of spray droplets are carried out using phase Doppler interferometry (PDI) in the fully developed spray. The spray from the RGCSCA is comprised of two distinct spray morphologies: a central dense spray of finer droplets and an outer coarse spray. The mean drop size of the central spray exhibits a decreasing trend with the increase in J whereas that of the outer coarse spray is independent of J. The radial profiles of the mean velocities of sprays at different J are presented. For the sprays with low inertia liquid sheets, the shape of mean axial velocity profiles is Gaussian.