The injection of a fuel spray into a cross stream was studied for its application in rapid fuel-air mixing for lean combustion processes. The fuel is injected as either a discrete stream or as a partially to fully atomized jet of droplets. Of particular interest was the penetration of the outer and inner edges of the spray of liquid fuel into the gaseous airstream. The experiment focused on exploring the effect of flow conditions on the spray surface trajectories from the point of injection to a downstream distance of z/Dfuel= 35. Tests were conducted under ambient pressures of 1, 3, and 5 atm at atomizing air pressure drops varying from 0 to 4.8% for a jet-A fuel flow of 0.18 g/s and a baseline crossflow air velocity of 38 m/s. A modified definition of the jet-to-crossflow momentum-flux ratio q2was developed to accommodate a two-phase jet and was subsequently used to obtain a relationship between the flow conditions and the spray surface trajectories. The effect of the degree of atomization in the Spray resulting from the change in operating conditions was incorporated by implementing a pressure ratio correction factor into the correlating equation. © 2001 American Institute of Aeronautics and Astronautics, Inc.