Experimental and Numerical Evaluation of the Cavitation Performances of Self-Excited Oscillating Jets

Self-excited oscillating jets (SOJ) are used in several practical applications. Their performances are significantly affected by structural parameters and the target distance. In this study, a geometric model of the SOJ nozzle accounting for multiple structural parameters is introduced, then the related cavitation performances and the optimal target distance are investigated using a Large-Eddy Simulation (LES) approach. Results are also provided about an experiment, which was conducted to validate the simulation results. By analyzing the evolution of the vapor volume fraction at the nozzle outlet, a discussion is presented about the effect of the aforementioned structural parameters on the cavitation performances and the target distance. It is shown that the distribution of cavitation clouds at the outlet of the SOJ nozzle displays a non-monotonic trend (first increasing, then decreasing). Under working conditions with an inlet pressure of 4 MPa, a SOJ nozzle outlet/ inlet diameter ratio (D-1/D-2) of 1.2, and a chamber diameter ratio (D/L) close to 1.8, the nozzle outlet cavitation performance attains a maximum. The optimal structural parameters correspond to the optimal target distance, which is near 50 mm. The experiments have revealed that the SOJ nozzle with the above parameters displays a good cavitation erosion effect at the target distance of 50 mm, in satisfactory agreement with the numerical simulation results.