基于气泡动力学的高坝下游总溶解气体过饱和生成机理及浓度预测模型研究

The total dissolved gas (TDG) supersaturation observed in a spillway that flows downstream various hydraulic structures has long been recognized as having a negative environmental effect on fish and aquatic organisms. The bubble dynamics and interface mass transfer mechanism relate to the generation process of TDG supersaturation is studied in this research. Firstly, the influence rules of TDG generation are discussed related to different bubbles (group) under different hydrodynamic conditions through laboratory experiments. And the bubble dynamics and mass transfer mechanism are combined to obtain the mass transfer coefficient between the air-water interfaces. And then considering the bubble size distribution, the rule of mass transfer between air-water interfaces is revealed. Moreover, TDG concentration transport equation is provided taking into account the mass transfer coefficient and the mass transfer rule between air-water interfaces based on the dynamic characteristics during the high dam discharges. The concentration prediction model is established finally, which can be applied to improve the accuracy of concentration distribution in the downstream. It is believed that this study can lay the foundation for the measures to mitigate the adverse effects of TDG supersaturation.

高坝泄水导致的总溶解气体过饱和及其对特定鱼类不利影响问题日渐突出。本项目针对总溶解气体过饱和生成过程的气泡动力学行为及界面传质机理开展研究。首先通过总溶解气体过饱和室内机理实验，探讨气泡（群）在不同的水动力学条件下对过饱和总溶解气体生成过程影响规律，结合气泡动力学及界面传质机理，获得总溶解气体过饱和水气界面传质系数。然后考虑气泡尺寸的分布，揭示不同的气泡分布规律下水气界面传质准则。最后结合界面传质系数和界面传质准则，基于高坝泄水的水动力学特性，提出高坝泄水TDG过饱和浓度输运方程，建立高坝下游TDG过饱和浓度预测模型，提高高坝下游TDG过饱和浓度分布预测的准确性，为促进TDG过饱和不利影响减缓措施的研究奠定基础。

高坝泄水导致的总溶解气体过饱和及其对特定鱼类不利影响问题日渐突出。本项目针对总溶解气体过饱和生成过程中不同曝气条件下气泡分布遵循的气泡动力学规律及界面传质机理开展研究。首先通过总溶解气体过饱和室内机理实验，包括气泡尺寸、紊动强度等研究，获得对过饱和TDG生成有重要影响的水动力学指标。然后将曝气传质过程分为水-气泡界面传质和水-自由表面传质两部分，通过不同曝气量下气泡尺寸分布及破碎聚并对过饱和总溶解气体传质过程影响规律的研究，揭示基于气泡动力学的气泡分布规律及水气界面传质准则，获得总溶解气体过饱和水气界面传质方程关键参数。最后结合界面传质系数和界面传质准则，基于高坝泄水的水动力学特性，考虑曝气气泡分布对过饱和TDG的释放系数的影响，建立高坝下游TDG过饱和两相流浓度预测模型，结果表明本项目建立的浓度预测模型可以提高高坝下游TDG过饱和浓度分布预测的准确性，为促进TDG过饱和不利影响减缓措施的研究奠定基础。