Study on Cavitation Erosion Mechanism and its Prediction

该项目为期两年，主要目的是研究空化侵蚀机理及其预测。空泡塌陷产生的冲击力是空泡塌陷的关键特性，其测量是研究空泡塌陷机理和预测空泡塌陷的重要手段。1995年和1996年，两名成员在格勒诺布尔IMG呆了两个月，进行关于传感器可靠性和准确性的合作研究实验。在涡蚀蚀试验装置Cavermod上对两种压电传感器（压电陶瓷和PVDF）和一种新型MgO晶体传感器进行了测试。结果表明，三种传感器的增益具有很好的一致性，可以作为标准传感器使用。以下是本项目成员所做的研究。云空化与撞击涡空化的数值分析。通过分析金属表面凹坑形状估算冲击压力分布。基于Strouhal相似性和水锤效应的模型坑数对原型侵蚀强度的预测。从测量的冲击力分布预测侵蚀强度。提出了一种无需实验即可预测冲击力分布的方案。流体性质（如声阻抗、表面张力、粘度）对侵蚀的影响。

The main objective of this two year program is research on mechanism of cavitation erosion and its prediction.Impact force caused by collapsing cavity bubble is a key property and the measurement is desirable mostly both for research of the mechanism and for the prediction. Two members stayd two months in 1995 and 1996 at IMG,Grenoble for cooperative research experiments on the reliability and the accuracy of sensors. Two types of piezo sensors (piezo ceramic and PVDF) and a new sensor of MgO crystal were tested in a vortex cavitation erosion testing facility, named Cavermod. The gain of the three sensors agreed very well among them and it was confirmed that those sensors can be used as standard.The following researches were made by the members of the present program.1. Numerical analysis of cloud cavitation and impinging vortex cavitation.2. Estimation of impact pressure distribution by analysing measured pit shapes on metal surface.3. Prediction of erosion intensity on prototype from pit counting of model assuming Strouhal similarity and water-hammer effect.4. Prediction of erosion intensity from measured impact force distribution.5. Proposal of a scenario for prediction of impact force distribution without experiment.6. Effect of fluid properties such as acoustic impedance, surface tension, viscosity, on erosion.