Jetting from cavitation bubbles due to multiple shockwaves
Jetting from cavitation bubbles due to multiple shockwaves
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DOI：
10.1063/1.5060645
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发表时间：
2018-11
影响因子：
4
通讯作者：
O. Supponen;Takahito Akimura;T. Minami;T. Nakajima;S. Uehara;K. Ohtani;T. Kaneko;M. Farhat;Takehiko Sato
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文献类型：
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作者：
O. Supponen;Takahito Akimura;T. Minami;T. Nakajima;S. Uehara;K. Ohtani;T. Kaneko;M. Farhat;Takehiko Sato
本文介绍了由空化微泡形成的微射流的实验观测。水下放电作用于平坦的自由面之下，产生一次压缩波，当自由面和火花泡界面反射时，该波经历几次相位反转。第一次反射产生张力波，在液体中产生一团二次空化气泡，其中一些在破裂时形成微喷流。这些反射的调谐使得能够有效地控制气泡云中的微喷流方向。所有位于火花泡和自由表面之间的微泡射流都径向远离火花泡。置于电极和自由表面之间的氧化铝平板的机械响应产生准平面压缩波，该压缩波在自由表面和平板的多次反射后，使微射流朝向平板相同的方向。这些观测表明，喷流方向主要由次生压缩波决定，次生压缩波是作用于足够大的空化气泡的第一个也是最高能量的压缩波。
We present experimental observations of microjets formed by cavitation microbubbles. An underwater electric discharge, applied beneath a flat free surface, produces a primary compression wave, which undergoes several phase inversions upon reflections from the free surface and spark-bubble interface. The first reflection yields a tension wave, which produces a cloud of secondary cavitation bubbles in the liquid, some of which form microjets upon collapse. The tuning of these reflections enables an effective control of the microjet direction in the bubble cloud. All of the jets of the microbubbles between the spark bubble and free surface are directed radially away from the spark bubble. The mechanical response of an alumina plate placed between the electrodes and free surface generates a quasi-planar compression wave, which, following its multiple reflections from the free surface and plate, orients the microjets in the same direction toward the plate. These observations imply that the jet direction is determined mainly by the secondary compression wave, which is the first and thus most energetic compression wave acting on a sufficiently grown cavitation bubble.