分形裂缝中空化泡溃灭机理及其空化清洗效应研究

影响水工建筑物安全的水下裂缝在修补前要进行必要的清洗，能够深入裂缝的空化清洗是一种高效的物理手段。然而，混凝土裂缝具有复杂的分形几何特征，现有空化泡与固壁间的相互作用研究尚无法满足工程诉求。项目以空化泡溃灭与具有分形特征的裂缝壁面间的相互作用为对象开展研究。首先，创新性地引入基于介观视角的格子Boltzmann方法，利用其多相流、复杂几何边界数值建模优势，构建高效的汽-液-固多相耦合数值模型；其次，提出几何特征可控的实体裂缝模型构造方法，构建与数值模型几何特征一致的实验模型，以通过实验验证数值模型的有效性；最后，通过开展系列数值实验，以分形几何参数为桥梁建立空化泡溃灭各物理量时空演化与分形裂缝几何特征之间的量化关系。项目拟从微观、宏观两个层面揭示分形裂缝与空化泡相互作用的机理及其空化清洗效应，为实现水下裂缝高效清洗奠定理论和技术基础，也为研究空化泡与任意复杂几何边界相互作用探索有效路径。

The underwater fractures which are the potential risks of the hydraulic structures must be cleaned before repaired. The cavitation cleaning is one of the important physical methods which can deep into the fractures and clean the inner walls effectively. However, the fractures have complex fractal features. The weak study of the interaction mechanism between the cavitation bubble and the fractal fracture can’t meet the demand of engineering well. This project focuses on the principles of the cavitation cleaning in fractal fracture for higher efficiency. Firstly, the lattice Boltzmann method, which is based on mesoscopic kinetics, is introduced innovatively in the project. Due to the advantages in the respect of multiphase and complex boundary modeling, it will be valid and efficient to model the vapor-liquid-solid multiphase fluids. Secondly, the constructing approach of fracture sample with controllable geometry features is proposed for the consistency between numerical model and the corresponding experimental sample. So the purpose of the experiments is to verify the numerical models. Finally, a series of simulations will be developed to investigate the quantitative relationship between collapsing cavitation bubble and fractal wall base on a series of fractal parameters. The achievements on two levels are expected. For microcosmic level, the microcosmic mechanism of interaction between collapsing cavitation bubble and fractal feature can be revealed. For microscopic level, the interaction mechanism and the cleaning effects between the fractal fracture and the collapsing cavitation bubble with shock wave and jets. As a result, it is expected that a set of experiment and analysis system on cleaning the fractal fracture to establish the theoretical foundation and the technical support for cleaning the underwater fracture effectively, and to expand the method to investigate the interaction between cavitation bubble and arbitrary complex geometry boundary.