ILASS Americas, 22 nd Annual Conference on Liquid Atomization and Spray Systems, Cincinnati, OH, May 2010 Pressure Swirl Atomization of Water-in-Oil Emulsions C.D. Bolszo, A.A. Narvaez D. Dunn-Rankin, V.G. McDonell 1 , and W.A. Sirignano Department of Mechanical and Aerospace Engineering University of California, Irvine Irvine, CA 92697-3550 USA Abstract The atomization of surfactant stabilized and natural, unstable water-in-oil emulsions injected into an ambient envi- ronment are investigated experimentally. Fuel flow conditions typical in large-scale gas turbine applications are stu- died. A specialized setup is used to generate controlled emulsions stabilized by addition of surfactants. The emul- sion generation process used allows control over the discrete phase droplet sizes within the emulsions. The spray droplet sizes are measured using laser diffraction and the spray pattern is measured using patternation. The results shown that the surfactants do affect the size of the atomized liquids, but in a manner expected based on the change in physical properties. Emulsification can reduce or increase the size of the spray depending upon the amount of water used. Atomization can change the size distribution of the discrete phase depending upon the initial sizes present and the injection pressure used. For the conditions studied, the stabilized emulsions performed very similar- ly to natural unstable emulsions as long as the unstable emulsion was produced shortly prior to atomization (i.e., <1 sec) and was produced with sufficient shear as to result in a fine discrete phase droplet size. Finally, it is observed that the atomization process also lead to a slight separation of components, with the denser water found preferential- ly at the outer edges of the spray. This was observed for both stabilized and unstable emulsions. Overall, the results obtained provide significant new insight into how the characteristics of the emulsion affects atomized spray. 1 Corresponding Author, mcdonell@ucicl.uci.edu