Analogy Between Cavitation Development and Solid Fracture Process Evaluated by AE Method

为了研究空化发展与固体断裂过程之间的相似性，采用声发射方法测量了空化流中的声发射脉冲数和脉冲高度分布，并与空化和应力-应变关系进行了比较。结果表明：（1）从亚空泡状态到超空泡状态的空泡过程与固体的断裂过程非常相似，在空泡过程和断裂过程的临界状态下，声发射脉冲数-空泡数曲线和空泡数-应力曲线都有两个峰值。(2)在高空化数和高应力区的第一峰值处的声发射信号为连续爆发型，而在低空化数和低应力区的第二峰值处的声发射信号为孤立爆发型。这一事实表明了它们之间的相似性。(3)由脉冲高度分布计算的指数在屈服点的起始和结束处均呈正态分布。这一事实可用来评价这两个过程的相似性.

In order to study the analogy between cavitation development and solid fracture processes, the number of AE pulses and the pulse-height distributions were measured by means of acoustic emission AE method, both in the cavitating flow past a fence and in tensile deformation of mild steel, with respect to cavitation aspects and stress-strain relation. The results are summarized as follows ;(1) Cavitation process from the subcavitation state to the super-cavitation state is very similar to the solid fracture process, since both the number of AE pulses - cavitation number curve and the number - stress curve have two peaks in the critical state of the cavitation process and the fracture process.(2) The AE signal at the 1st peaks in the highly cavitation number and the stress regions, is the successive burst-type, while the isolated burst-type signal takes place at the 2nd peaks in the lower cavitation number and stress regions. This fact suggests the similarity between them.(3) The exponents calculated from the pulse-height distributions show the normal distribution near the inception and the end of the yield point. This fact is available to evaluate the analogy both processes.