Investigation on unsteady flow characteristics of an artificial-submerged cavitating jet based on the LES approach

Cavitating water jets have a wide range of applications in machining, surface cleaning and rock drilling. However, their effectiveness is constrained by the dependence on submerged environments. This study addresses this limitation by numerically investigating the characteristics of unsteady flow evolution of a high-speed free cavitating water jet under a non-submerged condition using a dual nozzle with concentric configuration. The turbulent cavitation flow is simulated using the large eddy simulation method combined with the Schnerr-Sauer cavitation model. Comparisons between the simulated and classical experimental results on the shedding of the outer low velocity water waves validate the effectiveness of the simulation. The study analyzes the characteristics of flow field, including velocity distribution, pressure distribution, and vapor-phase volume fraction, and observes cavitation evolution phenomena such as cavitation growth, shedding, contraction, and collapse. It is found that the cavitation cloud forms in the jet core, and their formation is delayed in the non-submerged condition due to low-velocity water. The development of the cavitation cloud is closely related to the core dynamics, and its collapse results in localized high pressure. These findings provide valuable insights for the engineering applications of artificial-submerged cavitating water jets.