ID 387

Effects of Changing Various Nozzle Geometry on Cavitation and Spray Angle

 

Abstract:

The purpose of this study is to visualize and to analyze the variation of cavitation flow characteristics according to the aspect ratio of the nozzle. The transparent acrylic nozzles were used in order to facilitate observation. The cross-section of test nozzles has a rectangle shape with very narrow width instead of a circular shape for more certain visualization of cavitating flow. Three nozzles with a width of 2, 3, 4mm and length of 8 mm were made and tested respectively. The injection pressure was set to 1 ~ 4bar in 0.1 bar increments, and the inside of the nozzle was visualized using a shadow graphic visualization technique using a high-speed camera and a metal-halide lamp light source. The characteristics of the spray angle according to cavitation length and thickness inside the nozzle were analyzed from captured images using image processing code. The larger the aspect ratio of the nozzle, the more cavitation occurred. In addition, the entry into the hydraulic flip occurred at lower pressures. Cavitation length and thickness increased with increasing injection pressure, and cavitation maximum thickness accounted for 25 ~ 27% of nozzle width. As the cavitation grew, the spray angle increased, and the spray angle and flow rate decreased drastically when entering the hydraulic flip.