The breakup of turbulent liquid jets by cavitation bubbles was investigated by artificially introducing them by focusing laser light into the jet. The induced surface deformations and ejected liquid structures were characterized using shadowgraphy with a high-speed video camera. The flow velocity of the liquid jets, which were ejected from a 6 mm nozzle, was varied by adjusting the injection pressure from 1 to 5 bar. Deionized water and a dipropylene glycol–water mixture were used to compare the breakup of liquid jets with different surface tension and viscosity. Surface deformation and breakup were found to occur in two stages. One was early breakup of liquid strings into tiny droplets. This was followed by the formation of a larger structure separating into ligaments and larger drops. Averaged time-resolved one-dimensional plots were introduced and implemented to analyze breakup statistically, to address the problem of shot-to-shot variations in the breakup due to the turbulent condition of the jets. Bubble-induced breakup could easily be distinguished from spontaneous breakup with this method. Both the position of bubble formation and the injection pressure had an influence on the scale of the breakup. The deformation of the jet surface was highly affected by shear. The structure of the deformation became less intact when the surface tension was lower. The sizes of the drops produced during the second stage of breakup were analyzed. The bubble-induced breakup produced smaller drops than the spontaneous breakup at lower injection pressure. As expected, lower surface tension favored droplet detachment and smaller sized drops.

中文翻译：

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湍流液体射流中激光产生空化气泡引起的表面破裂分析

通过将激光聚焦到射流中来人为地引入空化气泡，研究了湍流液体射流被空化气泡的破坏。诱导的表面变形和喷射的液体结构使用带高速摄像机的阴影成像进行表征。通过将注射压力从 1 巴调整到 5 巴来改变从 6 毫米喷嘴喷射的液体射流的流速。去离子水和二丙二醇-水混合物用于比较具有不同表面张力和粘度的液体射流的破裂。发现表面变形和破裂分两个阶段发生。一种是液体串早期分解成微小的液滴。随后形成了更大的结构，分为韧带和更大的水滴。引入并实施了平均时间分辨一维图以统计分析破裂，以解决由于射流的湍流条件引起的破裂中每次射击变化的问题。使用这种方法可以很容易地将气泡诱导的破裂与自发破裂区分开来。气泡形成的位置和注入压力都对破裂的规模有影响。射流表面的变形受剪切影响很大。当表面张力较低时，变形结构变得不那么完整。分析了第二阶段破碎过程中产生的液滴的尺寸。在较低的注射压力下，气泡引起的破裂比自发破裂产生的液滴更小。正如预期的那样，较低的表面张力有利于液滴脱离和较小尺寸的液滴。