Numerical Investigation on Characteristics of Rotating Ultra-high-pressure Water Jetting

Ultra-high-pressure (UHP) water jetting is widely applied in ship rust removal due to their high energy density and eco-friendly characteristics. However, the influence of nozzzle’s rotating motion on the impact characteristics of water jetting requires further investigation. Based on the numerical simulation scheme incorporating cavitation and sliding mesh models, and considering liquid compressibility and nozzle rotating speed, a straight conical convergent nozzle model was constructed. The variations in key parameters, including flow field morphology, turbulent kinetic energy, shear stress, were investigated under different nozzle rotating speeds. The results indicate that nozzle rotation induces varying degrees of asymmetry in the jet flow field, causing the jet core to deviate, accompanied by shear layer thickening and an expanded turbulence range. As the nozzle rotating speed increases, the peak shear stress of the jet impact gradually decreases. To maximize operational efficiency, an evaluation method based on the "sweep time-sweep length-moving speed" relationship was established. By introducing a minimum sweep time constraint, this method quantitatively analyzes the non-linear relationship between nozzle rotating speed and translation speed. Using the theoretical maximum translation speed as a criterion, the optimal nozzle rotating range was obtained. These findings provide a theoretical basis for the design of process parameters in UHP water-jets cleaning systems.