High-pressure water jets are often used as a tool for cleaning, cutting or for modification of the surface morphology. The nozzle design has a considerable influence on cavitation and wear effects as well as on the nature of the exiting jets. Different applications are affected by different flow regimes, such as cavitation or hydraulic-flip, which depend on the radius of the nozzle edge.

In this work, the turbulent two-phase flow within two different nozzle types is analyzed using Computational Fluid Dynamics. The focus was to establish a relationship between the geometry of these nozzles and the flow phenomena as well as between wall shear stress and the wear, which leads to the change of the water jet shape and reduces the lifetime of high-pressure nozzles. The performed variation of the nozzle edge from sharp to round showed a significant influence on the maximum wall shear stress and cavitation. Additionally, the inner surface of used nozzles was investigated with Scanning Electron Microscope. Numerous marks of erosion were found at the nozzle edge. For the validation, the volumetric flow rate through the nozzles was measured at different inlet pressures and compared with the simulation results, which showed a good agreement.

高压水射流通常用作清洁，切割或改变表面形态的工具。喷嘴的设计对气蚀和磨损效果以及出口射流的性质有很大影响。不同的应用会受到不同的流态的影响，例如空化或液压翻转，这取决于喷嘴边缘的半径。

在这项工作中，使用计算流体动力学分析了两种不同喷嘴类型内的湍流两相流。重点是要在这些喷嘴的几何形状与流动现象之间以及壁切应力与磨损之间建立一种关系，从而导致喷水形状的变化并缩短高压喷嘴的使用寿命。喷嘴边缘从尖锐到圆形的变化表明对最大壁切应力和空化有重大影响。另外，用扫描电子显微镜研究用过的喷嘴的内表面。在喷嘴边缘发现了许多腐蚀痕迹。为了进行验证，在不同的入口压力下测量了通过喷嘴的体积流量，并将其与模拟结果进行了比较，结果显示出良好的一致性。