不同环境压强下激光空泡溃灭射流的实验研究

Experiment investigation on the liquid jet of laser-induced bubble in different ambient pressures

为了研究环境压强对固壁面附近激光空泡溃灭射流的影响,采用光偏转方法对固体壁面附近空泡溃灭行为进行了实验研究,得到了不同环境压强下空泡的溃灭时间、溃灭射流冲击压强。结果表明,相同激光能量下,环境压强对空泡溃灭时间、射流冲击压强都有非线性的影响关系,环境压强越大,溃灭时间越小,射流冲击压强越大;在空泡溃灭的前期,泡壁加速率较小且受环境压强的影响较小;在溃灭的后期,射流形成,空泡上表面泡壁中心点速率迅速增大,且相应阶段的加速率随着环境压强的增大而增大。这一结果对激光水下加工及空泡动力学的研究有积极的意义。

In order to study effect of ambient pressure on the liquid jet of laser-induced bubbles, the collapse time and the water hammer pressure of the liquid jet were obtained after studying the collapse action of the bubbles by means of a fiber-optic diagnostic technique based on probe beam deflection （PBD） in experiments. The data indicate that the collapse time decreases nonlinearly with the ambient pressure increasing, and the water hammer pressure increases nonlinearly with the ambient pressure increasing. At the initial stage of the collapse stage, the acceleration of the bubble wall and the effect of the ambient pressure on the acceleration are very small ; at the final stage of the collapse stage, the velocity of the center of the top bubble wall increases very quickly, and the acceleration increases with the ambient pressure increasing at the same stage. It＇ s helpful to underwater laser processing and study about cavitation bubble dynamics.