缩放型喷嘴空化射流空泡云演化规律的试验研究

Cavitation jet tests are carried out on a缩放型 nozzle (这里“缩放型”英文可能是convergent-divergent或者其他专业词汇，需根据实际情况确定) based on high-speed photography technology to reveal the characteristics of the cavitation jet flow field under different inlet pressures and analyze the influence of the inlet pressure on the evolution law of the cavitation cloud. The results show that the bubble cloud formed by the submerged cavitation jet changes periodically, that is, it contains four different stages of cavitation inception, development, shedding, and collapse within one cycle, and reaches the maximum bubble area, density, and width when the cavitation cloud is shed. As the jet inlet pressure increases, the jet velocity formed by the nozzle accelerates, the velocity gradient in the jet boundary layer increases, and the shearing effect between the jet core area and the accompanying flow intensifies. The length, area, and density of the cavitation cloud generated by the high-speed jet all show an increasing trend. At the same time, as the inlet pressure increases, the turbulent kinetic energy in the boundary layer increases, intensifying the irregular movement of some fluids, resulting in a more blurred boundary of the cavitation cloud and a staggered distribution, and the shedding frequency of the cavitation cloud continuously increases. The research results have important theoretical significance and guiding value for improving the application of cavitation jets in the fields of metal material strengthening, petroleum drilling, rock breaking, etc.

基于高速摄影技术对缩放型喷嘴进行空化射流试验,以揭示不同进口压力下空化射流流场特性,分析进口压力对空泡云演化规律的影响.结果表明:淹没式空化射流形成的泡云呈周期性变化,即在1个周期内包含空化初生、发展、脱落、溃灭4个不同阶段,并在空泡云脱落时达到最大的空泡面积、密度和宽度.由于随着射流入口压力的增大,喷嘴形成的射流速度加快,在射流边界层内速度梯度增大、射流核心区与伴随流的剪切作用增强,高速射流所产生的空泡云长度、面积和密度均呈增大趋势.同时,随着进口压力的增大,边界层内湍动能增大,加剧了部分流体的不规则运动,导致空泡云边界更加模糊且呈交错分布,空泡云的脱落频率不断增大.研究结果对提高空化射流在金属材料强化和石油钻井、破岩等领域的应用具有重要的理论意义和指导价值.