中文摘要：

要实现超高压水射流的稳定性调控首先必须对其流动特性展开探索。设计了四种喷嘴出口流道结构,对其产生的射流进行了测量,并结合数值模拟对实验反映出的物理现象进行了诠释。结果显示：圆柱形出口流道喷嘴,其射流流动形态受雷诺数变化影响不明显,射流与环境气体界面近似为圆锥。而圆柱与圆锥组合型出口流道喷嘴,其射流结构形态随雷诺数变化显著。这表明具有特定结构,不与射流直接接触的出口流道,也能对气液边界层湍流产生显著影响,从而对射流流动特性起到调节作用。在雷诺数120000~130000范围内,提出能显著提高射流能量集中性的最佳结构形式及参数：锥角为90°,圆锥与圆柱组合型出口流道。这些发现为最终实现射流流动控制提供了研究方向的引导。

英文摘要：

In order to realize the stability-control of ultra-high pressure water jet,its kinetic and dynamics should be unfolded firstly.Four nozzles with different exit structures were designed.The jets discharged from each of these nozzles were measured and parameters indicating stability of liquid jets were presented.We also explored the flow field around the initial section of jets by numerical simulation.The dependency of jet stability on both turbulence and nozzle configuration is discussed.The results show that the jets＇ shapes of the nozzle which has a cylindrical exit struture are less affected by the Reynolds numbers.Conical interface between jet and ambient air is found.The jets from the nozzle which has combined exit structures（cylindrical and conical） are more subject to turbulence intensity.The shear layer can be affected by the specific nozzle structure which is not attached by jets.Evidence proves that the flow characteristics of the jets can be controlled by the specific nozzle exit structures effectively.In the range of Reynolds numbers from 120000 to 130000,the nozzle with certain type of outlet（a cylindrical section connected to a conical section with a cone angle of 90°） has the best performance measured by jet coherency.These findings provide a guideline for practical stability-control technique of ultra-high pressure water jet.