An optical study of high-pressure water-jet dynamics

This paper considers the results of an optical study of high-speed fluid jets ejected from a nozzle at 400 MPa. The objective was to study two-phase flows under extreme conditions and to analyze the possibility of the optimization of the device design. The process of a high-speed water jet as it exits the focusing tube of the Flow WaterJet Mach3 abrasive cutting machine, along with its development, and the state of the stationary flow are considered. The shadow method was used to investigate the initial stage of high-speed water-jet formation, as well as the jet-head dynamics during the first 200–400 µs after ejection at 400 MPa. A Photron FASTCAM SA5 high-speed camera with a frame rate of one million shots per second and an exposure time of 1 µs and a FLIR SC7000 infrared thermal camera with a frame rate of 400 shot/s and an exposure time of 1 ms were employed in order to study the jet-formation process. The spatiotemporal characteristics of the jet-development process were analyzed. The jet velocity and the starting jet head acceleration were measured by post-processing of digital images.