明渠高速掺气水流是水利与环境工程中最常见的工程水力学问题之一，对于工程运行安全与环境生态保护有多方面的影响，而水流自由面掺气形成机理目前仍不明确。前期我们研究发现自由面凹陷形态演变是导致掺气的直接成因，细观形态及其尺度特征在失稳卷吸气泡过程中存在显著改变。由于水流紊动发展是导致自由面演变的根本原因，在前期研究基础上，拟结合系列物理模型试验与理论分析，研究明渠水流自由面形态演变过程对于不同水流紊动强度的响应机制，明确水流紊动-自由面形态-掺气之间的相关关系，揭示紊动作用下水流自由面卷吸掺气机理，建立失稳卷吸掺气细观形成临界条件，并将其引入明渠水气二相流浓度扩散分析模型，量化明渠高速水流掺气扩散量，明确自由面卷吸掺气机理在掺气水流形成发展过程中的基础性意义。通过本项目的研究，有望推动明渠水气二相流物质输移转化过程的基础理论研究与学科发展，为预测水流掺气发展变化规律提供理论基础。

Self-aeration in high-speed open channel flows is an important hydraulic issue in hydraulic and environment engineering projects, and it is essential to estimate the effects of air-water flows on the structure safety and ecological environment. However, the mechanism of free surface air entrainment of high-speed water flows is still not clear. According to our previous studies, the development of free surface deformation is a key factor on the air bubble entrainment, and the microscopic shape and scale properties change remarkably during the whole process. In the present study, the effect of flow turbulence intensity on the free surface deformation properties in open channel flows will be investigated based on theoretical and experimental studies. The relationship among flow turbluence, free surface deformation and aeration will be clarified, to reveal the mechanism of air bubble entrainment through free surface of high-speed open channel flows. The critical condition of hydraulic conditions for free surface air entrainment will be proposed, and the theoretical analysis model will be improved on the basis of this mechanism. The general influence of air entrainment on the air-water diffusion development in open channel flows will be analyzed. This project will promote the basis study on the air-water transport in two-phase flows, and provide theoretical foundation for the estimation on the aeration influence on engineering projects.