Study on Oscillation Characteristics and Flow Field Effects in Submerged Pulsed Water Jet

The self-excited oscillation pulsed waterjet (SOPW) offers simplicity and effective pressure source separation, making it widely utilized. This study investigates the oscillation characteristics and flow field effects of SOPW generated by a Helmholtz nozzle. A transfer function model for the nozzle is established, and the natural frequency is found to correlate with structural parameters such as the oscillation chamber’s cross-sectional area, length, and downstream nozzle diameter. Numerical simulations reveal optimal structural parameters that closely match experimental results, with errors under 15%. Notably, submerged pulsed jets exhibit faster velocity decay compared to non-submerged jets. Additionally, the study examines the effect of area discontinuity at the nozzle inlet on axial velocity, showing that the area enlargement or contraction enhances velocity at lower pressures but inhibits it at higher pressures. This work advances the understanding of nozzle design and the flow field behavior of SOPW.