Study of the Stages of Cavitation Development in Channels Based on Hydro- and Sonoluminescence Measurements

The conditions for the development of cavitation are studied using the effect of light emission from the liquid during the collapse of cavitation bubbles. This work presents the results of investigation into cavitation in technical fluids by recording hydro- and sonoluminescence. The conditions for the occurrence of hydro- and sonoluminescence were analyzed concerning the geometry of a narrow channel, utilizing a high-speed camera and a photomultiplier for recording. Universal threshold values for the deformation rate at which hydroluminescence occurs were obtained in the range of 10⁵–10⁶ s^–1, and a methodology was developed for recording hydro- and sonoluminescence in narrow channels to study the stages of cavitation development. In the developed experimental setup, the high-pressure circuit was divided into a pressure circuit and a measurement circuit. In the pressure circuit, the hydraulic oil pressure was generated using a gear pump. Through a hydraulic cylinder and a movable piston, it was transmitted to the fluid in the measurement circuit, which was then passed under pressure through a narrow channel. The proposed geometry of the narrow channel allowed for the separation of the phenomenon of hydroluminescence in the narrow channel and sonoluminescence with subsequent cavitation as the fluid exited into a diffuser owing to a drop in pressure. The design of the setup and the methodology enabled the investigation of cavitation effects for a wide range of technical fluids, including those aggressive to high-pressure pump materials. The obtained results can be utilized in improving the means of comprehensive diagnostics of lubricated friction units on the basis of the wear product parameters in oil, the methods for suppressing acoustic effects of cavitation, and more.