Numerical Simulation and Experimental Analysis of Cavitating Water Jets with Angular Nozzles under Surface Constraints

The effectiveness of oil pipeline cleaning is critical for minimising the frequency of reuse, and cavitation water jet technology presents a highly efficient and energy-saving cleaning method. However, the evolution behaviour of cavitation clouds under curved constraints, as well as the influence of nozzle structural parameters on cleaning performance, remains inadequately understood. In this study, high-speed imaging was employed to examine the effects of the target surface, target position, and inlet pressure on cavitation cloud evolution under curved constraints. In addition, large eddy simulation (LES) was utilised to model cavitation water jets in constrained geometries. The findings revealed that the cavitation cloud evolution cycle was shortened under curved constraints. As the target distance and inlet pressure decreased, the cavitation cloud evolution cycle, vapour phase concentration on the wall surface, and cavitation cloud width also decreased. The LES results were consistent with experimental observations. Using an orthogonal experimental design, the optimal combination of structural parameters for the angular nozzle was identified through range analysis. The results indicated that increasing the target distance led to higher vapour phase volume fraction and flow velocity on the target surface. The optimised nozzle significantly enhanced the cavitation effect at the target surface.