Flow-visualization and numerical investigation on the optimum design of cavitating jet nozzle

Abstract

Cavitating jet is widely used in drilling, rock cutting and ocean resource exploitation because of its strong erosion ability. The analysis of the relationship between the flow characteristics and the structure of cavitating jet nozzle is critical. Here, we utilized 3D printed technology and high-speed photography to design visualization experiments to analyse the impact of the variation of resonator and throat size of the organ-pipe self-resonating cavitating nozzles on the cavitation characteristics through image processing. The velocity field, pressure field and vapor volume fraction injected by the nozzle were taken as the objective functions to study the influence of different structural parameters on the cavitation effect based on FLUENT 19.0 software, and the results were compared with the experimental results. The results show that increasing the length and diameter of the resonator contributes to the occurrence of cavitation and the structure stability of the flow field. However, excessive size affects self-resonant of the nozzle and makes it difficult to form resonance effect. In this study, the optimal values of nozzle throat length and divergent angle are twice the throat diameter and 40°, respectively. This research provides an integrated research method to study the optimization of self-resonating nozzle and cavitating jet characteristics.