Effect of Ambient Pressure on an Airblast Spray Injected into a Crossflow

Abstract

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 e ow 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 e ow of 0.18 g/s and a baseline crosse ow airvelocity of 38 m/s. A modie ed dee nition of the jet-to-crosse owmomentum-e ux ratioq2 wasdeveloped to accommodatea two-phasejetandwassubsequentlyused to obtaina relationshipbetween the e ow conditions and thespray surface trajectories. The effect of the degree of atomization in thespray resulting from the change in operating conditions was incorporated by implementing a pressure ratio correction factor into the correlating equation. Nomenclature Aairbl = area associated with the airblast air, assumed as the difference between Aspray and Aliquid Aliquid = area associated with the fuel injection orie ce Aspray = area associated with the spray injection orie ce Cd = orie ce discharge coefe cient cn = correlation constants, n D0;1;2;3 Dfuel = fuel injection orie ce diameter Dspray = spray injection orie ce diameter q1 = single-phase jet-to-crosse ow momentum-e ux ratio q2 = two-phase jet-to-crosse ow momentum-e ux ratio V = velocity Wecross = crosse ow-associated Weber number ΩairV 2 crossDfuel=ae x = penetration distance z = downstream distance Ω = density