Effect of Orifice Geometry on Column Trajectories of Liquid Jets in Crossflows

Effects of orifice geometry on liquid column trajectories of liquid jets in subsonic crossflows were experimentally studied. One circular and four elliptical plain-orifice injectors with different aspect ratios of 1/3 to 3, were designed and utilized. By changing the injection pressure drop from 1 bar to 6 bar with an increment of 1 bar, and thus the liquid–air momentum flux ratio from 15 to 106, back-lit spray photographs of liquid jets in crossflows were taken and then analyzed using an in-house code to detect the upper boundary and centerline of the liquid jet before the breakup point. Analytical liquid column trajectories for circular and elliptical liquid jets were derived through simple assumptions and compared with present experimental data. It was found that the aspect ratio affected the difference between the analytical drag coefficient and the experimental one. Novel empirical equations for liquid column trajectories of circular and elliptical liquid jets in crossflows were suggested as a function of equivalent orifice diameter, liquid–air momentum flux ratio and aspect ratio. The results showed that the present empirical equation for the circular orifice injector could be reasonably applied to the elliptical orifice injectors when the aspect ratio was below one.