带柔性隔水幕的分层水库库区流-热-固耦合互馈效应及机制研究

Cold outflow problem frequently exists in large and medium reservoirs, and facilities of selective withdrawal are widely used to improve the outflow temperature. The flexible temperature-control curtain (TCC) is a newly developed facility of selective withdrawal, and can significantly influence the hydrodynamic and thermal distribution of reservoir area. Meanwhile, the stratified flow can cause remarkable deformation and displacement of curtain. This fluid-thermal-solid coupling influence in the stratified reservoir is vital to the water ecology and environment of reservoir area and the safety of hydraulic structures. Thus, a hydraulic physical model of TCC and 3-D hydro-thermal-tracer-TCC numerical model incorporating the dynamic mesh technique are to be built: Firstly, the formation, reinforcement, dissipation and discharge of the jet flow across the TCC are simulated, and the dynamic patterns of withdrawal elevation and thickness are analyzed. Secondly, the unstable interfaces of epilimnion, thermocline and hypoliminion are tracked, the thermal-storaging effect of TCC and the spatial-temporal progresses of thermal structure are revealed. The key factors of the outflow temperature are identified, and its quantitative expression is proposed. Thirdly, the phase relationships among the dynamic deformation and displacement of TCC, the repeating flow and the fluctuating temperature are analyzed. The mechanisms of the deformation and displacement of TCC because of the stratified flow are elaborated. This study contributes to improving the implementation effect of TCC, providing theoretical basis for the ecological and environmental management, and offering technical support for the design of selective withdrawal.

大中型水库下泄低温水问题显著，常采用分层取水来改善。隔水幕是一种新型柔性分层取水设施，在改变库区流场和水温场的同时，其自身也伴随水温分层流发生相应的动态形变位移，这种流-热-固耦合互馈效应对库区生态环境及隔水幕自身结构安全至关重要。本项目拟建立隔水幕分层取水物理模型和三维水动力-水温-示踪-隔水幕的耦合动网格数值模型：模拟隔水幕阻流扰动下的过幕射流形成-强化-扩散-出库下泄的流态衔接过程，揭示取水层高度垂向移动及厚度变化的动态特性；通过辨识变温层、温跃层、滞温层的分层界面运动轨迹，明确隔水幕影响下的库区蓄热效应及水温结构演变规律，提炼下泄水温关键影响因子及量化关系式；解析隔水幕平面/垂向形变位移与其引起的流场和水温场变化间的同步相位关系，探求分层水流反馈作用下隔水幕形变位移的诱发机制。本项目研究对保障隔水幕实施效果提供了理论基础，并为水库生态环境管理和分层取水设计提供了科学依据。

深水水库往往存在水温分层现象，由于常采用单一取水方式，出库水温明显异于天然来流，引起下游河道的水温水环境特征改变，尤其是春夏季节的出库低温水，对农田灌溉、河流养殖、河流水质和生态平衡均有不利影响。为改善出库水温条件，水库常设有分层取水设施。隔水幕布是一种较为新型的性分层取水设施，目前已有部分研究成果和工程经验，但主要关注它对出库水温的影响，而尚未分析其对库区水温结构的影响，也缺少对隔水幕布流-热-固耦合互馈效应的解析。本文以中国西南三板溪水库为例，通过数值模拟实验和物理模型试验，研究了深水水库中隔水幕布对库区水温的影响机理，并分析了其在动水环境中的水动力条件及受力机理。首先研究隔水幕布对出库水温的改善效果及对库区水温的影响，探讨各类型隔水幕布的适用范围；然后从结构安全角度，引入绕流运动理论，解析动水环境中的幕布水动力特征，分析不同布置方式下的幕布受力，也表明隔水幕布作为柔性体，在动水环境中具有大变形和微形变的特点，在恒定的水动力情况下，隔水幕布可以维持一定的稳定形状；最后进一步考虑水库存在的水温分层现象，探究分层流体对隔水幕布受力机理的影响。本文分别从实施效果和结构安全角度，系统探讨了隔水幕布分层取水方案在实际应用中的关键技术问题。所得研究成果极大丰富了水库分层流理论和分层取水工程方案，有利于改善流域水温时空分布特征，降低水库蓄水对生态环境的负面影响。