Research on the structures and hydraulic performances of the typical direct jet nozzles for water jet technology

Water jet technology has been widely used for many years. It is an effective and clean approach for breaking, cutting or cleaning materials. Nozzle is the crucial component for implementing the water jet technology in practice. The structural parameters of nozzle directly determine its hydraulic performance. In the meantime, the nozzle’s hydraulic performance directly determines the operational efficiency of water jet technology. The straight cone nozzle and the conical nozzle are two kinds of typical direct jet nozzles, which have been widely used in the practice. Comprehensively using the orthogonal experimental design, CFD numerical simulation, theoretical calculation, experiments of testing the water jets’ impact forces and breaking the artificial sandstones, the optimal structural parameters of straight cone nozzle can be obtained. Moreover, the impact force of water jet produced by the straight cone nozzle increases with its outlet diameter increasing significantly. In addition, the cylindrical outlet section of straight cone nozzle is good for improving its hydraulic performance, resulting that its hydraulic performance is better than the conical nozzle.