Experimental Comparison of Injection Characteristics of Elliptical and Circular Liquid Jets into an Air Crossflow

The flow characteristics of liquid jets issuing from elliptical and circular injectors into an air crossflow were experimentally investigated. Two elliptical injectors with different aspect ratio and a circular injector as the reference case with the same cross-sectional area was employed. The major axis of the elliptical nozzles was aligned parallel and perpendicular to the air crossflow direction. The liquid jet was visualized using shadowgraph technique and a high speed camera was used to record the instantaneous status of the jets. The liquid / air momentum flux ratio and air Weber number were varied to examine their effects on different parameters of the flow like liquid jet column trajectory, breakup point and breakup regimes. The results revealed that some characteristics of injected liquid jets into the air crossflow such as penetration depth and the trajectory of liquid jet were affected by changing the nozzle exit shape. Based on the obtained results elliptical liquid jets because of the lower stability than circular jet, break up sooner and penetrate lower into the air crossflow. As the normalized breakup height of circular jet is obtained 29.5 but the normalized breakup height of elliptic jet with the aspect ratio of 3 and when its major axis was perpendicular to the crossflow direction, is obtained 21.53. In this study two different breakup regimes were observed, column breakup and bag breakup regimes.