Вісник № 01. Гідравлічні машини та гідроагрегати

The article presents the results of the study of cavitation processes in technological equipment related to analytical phenomena that are accompanied by cavitation. One of the important factors accompanying cavitation processes is hydrodynamic luminescence. The information analysis of the existing theories of luminescence formation, including at hydrodynamic processes in liquids and gas-liquid environments is carried out that allowed to substantiate the basic conditions which provide emergence of the phenomenon of hydroluminescence. A literature search revealed that there is no unambiguous theory of the nature of sonoluminescence and hydroluminescence. These processes have several theories of their origin: thermal, electrical, quantum and even nuclear. Moreover, each theory is to some extent confirmed by the experiments of scientists, but at the same time is not fully disclosed. This ambiguous interpretation leads to the conclusion that the current situation cannot be considered satisfactory. Detailed experimental studies of this phenomenon are needed. For the practical study of the mechanisms of hydrodynamic luminescence, an experimental stand based on a hydrodynamic cavitator was developed and manufactured. This stand allows to investigate the cost characteristics of the cavitator, to observe and make photo and video fixation of the phenomenon of hydroluminescence in the flow of liquid or gas-liquid mixture, for which an ejector mixer was used. As a result of application of experimental-analytical method and technical visualization it is established that the phenomenon of hydroluminescence begins at an oil pressure of 20 bar, and at its saturation with inert gas – occurs at much lower pressures within 10 bar. According to our observations, with increasing flow velocity in the narrowing region, cavitation first occurs, then, with a further increase in the flow velocity, single sparks begin to appear, and at some point there is a "breakdown" and a stable glow. Based on the results of processing and analysis of experimental studies, a conceptual model of the stages of origin and development of the cavitation process and the accompanying effects is built. The conducted researches allowed to reveal the cavitation zones arising in the cavitator. Cavitation areas were identified with the help of high-speed video recording and the mechanism of its development was investigated. In addition, the visualized characteristics of the closed volume to some extent clarify the existing ideas about the behavior of the liquid and gas-liquid mixture in the nozzle. It is concluded that the phenomenon of hydroluminescence (triboluminescence) can be used as a method of cavitation visualization. At the same time, the management of workflows that accompany the phenomenon of cavitation is quite relevant because it allows you to deal with the undesirable consequences of cavitation.

Вісник № 01. Гідравлічні машини та гідроагрегати

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