Liquid jet core characterization in a model crossflow airblast atomizer

Abstract

Detail characterization of the liquid jet core in a model cross-stream airblast atomizer by application of the Optical Connectivity (OC) technique is the goal of the present paper. The unique ability of the technique in imaging the fluorescence signal exclusively from the jet core region facilitates simultaneous visualization of the liquid jet from the side- and the front-view with high background contrast. This allows measurement of some important primary breakup characteristics. The jet penetration and breakup length are obtained from the side-view images, while the front view images provides the jet width and the spreading angle. The above parameters are measured for a wide range of injector operating conditions. The measurement of mean jet trajectory and mean penetration/breakup length indicated large difference in comparison to the past studies based on experiments conducted in wind-tunnels. This is attributed to air flow confinement within the atomizer in the present case and also accurate measurement of breakup location in the OC technique. The range of the measured mean width of the jet and spreading angle indicated ’sheet breakup mode’ of the liquid jet for all injector operating conditions. Correlations are obtained to describe the evolution of different mean quantities with respect to relevant non-dimensional numbers. The fluctuations of jet breakup parameters are also measured. Some interesting correlations are obtained between fluctuations of different primary breakup characteristics which are discussed in the paper.