Experimental Analysis and Phenomenological Model for Liquid Jet Breakup in Swirling Flow of Air

This paper presents detailed analysis of an experimental investigation of the impact of swirl number of subsonic cross-flowing air stream on liquid jet breakup at an airflow Mach number of 0.12, which is typical in gas turbine conditions. Experiments are performed for four different swirl numbers (0, 0.2, 0.42, and 0.73) using swirl vanes at air inlet having angles of 0 deg, 15 deg, 30 deg, and 45 deg, respectively. Liquid to air momentum flux ratios (q) have been varied from 1 to 25. High-speed images of the interaction of liquid and air streams are captured and processed to estimate the jet penetration height as well as the breakup location for various flow conditions. The results show unique behavior for each swirl number, which departs from the straight flow correlations available in the literature. Based on the results, an attempt has been made to understand the physics of the phenomena and come up with a simplified physical model for prediction of jet penetration. Furthermore, the high-speed images show a dominant influence of liquid column fluttering on fracture mechanism (column or shear breakup mechanism).