Observations of cavitation erosion pit formation
Observations of cavitation erosion pit formation
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DOI：
10.1016/j.ultsonch.2013.01.011
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发表时间：
2013-07-01
影响因子：
8.4
通讯作者：
Petkovsek, Martin
中科院分区：
文献类型：
--
作者：
Dular, Matevz;Delgosha, Olivier Coutier;Petkovsek, Martin
先前的研究表明，单个空化气泡的坍塌可能会导致多个侵蚀坑(Philipp&Lauterborne[1])。但我们的初步研究表明，在某些情况下，一个空化坑可能是由多个空化事件造成的，这一点恰恰相反。本研究对这一现象进行了更深入的研究。研究了超声空化对薄铝箔的冲蚀作用。在这项研究中，我们用高速摄像机(>；1000fps)观察了单个凹坑的形成，并用立体观察法和遮光法对系列图像进行了定量评估。这使得能够重建凹坑形状的时间演化。结果表明，在最终穿孔之前，铝箔是如何多次变形的。据确定，较大的单个凹坑是由冲击波对同一区域的几次撞击造成的，这意味着它们只是凹坑集群(凹坑完全重叠的凹坑集群)的特例。结果表明，薄箔在空化作用下表现为膜的行为。结果表明，空蚀背后的物理机制主要取决于产生空化的方式(声学、流体力学、激光)和试件的特性(薄片、大块试件)，这使得不同实验装置的材料抗空化性能的比较成为问题。在空蚀试验范围内进一步发展由阴影形成形状的方法将使空蚀模型能够得到更好的评价。(C)2013爱思唯尔B.V.保留所有权利。
Previous investigations showed that a single cavitation bubble collapse can cause more than one erosion pit (Philipp & Lauterborn [1]). But our preliminary study showed just the opposite that in some cases a single cavitation pit can result from more than one cavitation event. The present study shows deeper investigation of this phenomenon. An investigation of the erosion effects of ultrasonic cavitation on a thin aluminum foil was made. In the study we observed the formation of individual pits by means of high speed cameras (>1000 fps) and quantitatively evaluated the series of images by stereoscopy and the shape from shading method. This enabled the reconstruction of the time evolution of the pit shape. Results show how the foil is deformed several times before a hole is finally punctured. It was determined that larger single pits result from several impacts of shock waves on the same area, which means that they are merely special cases of pit clusters (pit clusters where pits overlap perfectly). Finally it was shown that a thin foil, which is subjected to cavitation, behaves as a membrane. It was concluded that the physics behind erosion depends significantly on the means of generating cavitation (acoustic, hydrodynamic, laser light) and the specimen characteristics (thin foil, massive specimen), which makes comparison of results of materials resistance to cavitation from different experimental set-ups questionable.Further development of the shape from shading method in the scope of cavitation erosion testing will enable better evaluation of cavitation erosion models. (C) 2013 Elsevier B.V. All rights reserved.