中文摘要：

在喷嘴流道内嵌入中心体以诱发空化射流，借此来研究空化区形态及空化泡的空蚀作用。在不同相对直径条件下，研究自由射流条件下的射流流束宽度，进而判断射流流束的动态波动行为和能量分布特征。对自由射流和淹没射流，分别采用射流冲击固体壁面的实验方法，对被冲击固体表面的形貌进行图像分析。研究中将普通喷嘴与中心体喷嘴的射流现象进行对比。研究发现，中心体相对直径对空蚀程度影响较大，相对直径越大，空蚀程度越高；在淹没条件下的射流冲蚀固体壁面的效果优于非淹没条件，空化效应起着关键的作用；靶距是影响空蚀程度的重要参数，对于普通喷嘴和中心体喷嘴，射流效果与靶距之间的关系存在着差异，这些差异与空化现象密切相关。

英文摘要：

With a cylinder central body being embedded into the inner flow passage of a circular nozzle, cavitation is expected to be induced when the high pressure water flows past the cylinder whose axis is vertical to the jet direction. At different relative diameters, the width of the jet stream was studied which acts as the basis of the dynamic behavior and kinetic energy characteristics of the jet stream. Impingement on solid surface by the water jet was adopted to describe the flow characteristics from the impingement effects on the solid surface. The image of the impinged surface was analyzed by using image-processing software. Comparison study was also conducted between the impingement effects with central-body nozzle and ordinary circular nozzle. It is found in the study that the influence of relative diameter is remarkable in terms of the cavitation erosion. Large relative diameter leads to obvious cavitation erosion. The impingement effect under submerged condition is better than that under free condition and cavitation effects are proved. The stand-off distance（SOD） also plays an important role in the process of impingement. For the ordinary nozzle and central-body nozzle, variations of impingement effect with SOD are different, which is highly related to the cavitation effects.