FUNDAMENTAL INVESTIGATION OF LIQUID INJECTION IN SUPERSONIC CROSSFLOW: AN EXPERIMENTAL STUDY

Abstract

Experimental investigation of the liquid injection into a Mach 2.2 supersonic crossflow through a transverse single circular injector has been carried out in the present study. High-speed visualization techniques such as back-lit imaging, shadowgraphy, and schlieren imaging have been employed to investigate the flow and the liquid jet features. The present study provides a detailed analysis of the breakup behavior of a liquid jet introduced into a crossflow with a Mach number of 2.2 by categorizing it into distinct zones. The liquid jet breakup was induced by surface instabilities, leading to the formation of a protrusion structure that traveled downstream along the jet. The schlieren photographs captured the essential flow dynamics resulting from the liquid injection, such as the bow shock wave and the separation shock wave. Observations indicated that the location where the bow shock wave interacts with the upper wall shifts in the upstream direction as the liquid injection pressure is increased. Furthermore, a parametric analysis was conducted to assess the penetration height of the injected liquid and its variation relative to the injection pressure. The analysis revealed that the penetration of the jet was greatest at an injection pressure of 7 bar, succeeded by 5 bar and 3 bar, respectively. The minimal penetration height was recorded at an injection pressure of 1 bar. In a quantitative analysis, the penetration of a liquid jet was measured at various injection pressures at a normalized axial distance of 5. It was found that the penetration of the liquid jet with an injection pressure of 7 bar was 3.67 times greater than the liquid injection with an injection pressure of 1 bar.