含沙水流对稳定分层型水库水温结构影响的研究

Water reservoir temperature is of critical influence on reservoir and downstream aquatic environment and other temperature demand. The simulation of reservoir stratified temperature and sediment is difficult for the complexity of hydraulics, thermodynamics and sediment, and is not so precise in theory and experiment. According to the technical line of laboratory experiment, field observation and numerical simulation, inflow temperature, sediment content, particle size and stratification intensity in flume are measured to search the buoyancy coefficient while temperature and sediment influence each other. Sediment laden flow, development of density current and temperature distribution in reservoir are observed to master the law of temperature and sediment distribution. Based on the laterally averaged 2-D temperature and flow reservoir model, the capability of computing density current formation, transportation, diffusion and settlement is introduced to the model. While coefficients are specified by laboratory experiment and verified by field observation, finally the model is established to calculate water temperature and sediment couply.The model is being used in the research of the relationship of water temperature and sediment. The achievement is of great academic significance for the developing of reservoir water temperature and sediment pridiction theory.

水库水温对库区及坝下的水生环境及其它水温需求有着至关重要的影响，而水库的水力学和热力学特性、泥沙运动的复杂性使得耦合模拟库区水温分层与泥沙运动极为困难，并缺乏严谨的理论支撑和试验验证。本项目采用室内试验、原型观测与数值模拟相结合的技术路线，在室内水槽监测不同入流水温、含沙量、粒径、分层强度条件下槽内稳定分层水温结构破坏和重建的过程，探寻温差与泥沙相互影响下的浮力计算模式；原型观测中通过多点监测库区的泥沙入库与异重流发展、水温分布，掌握大型深水库的水温泥沙时空分布规律；在立面二维水温、水力学模型基础上，引入库区泥沙异重流形成、输移、扩散、沉降的计算模式，以试验成果率定模型参数，以原型观测成果验证模型，最终建立水温与泥沙耦合计算的水库宽度平均的立面二维温差-泥沙异重流数学模型，应用于水库水温与泥沙运动规律的关系研究中。本成果对水库水温和泥沙预报理论的发展具有重要的学术意义。

基于大型水库运动过程中出现的温度、泥沙分层现象，且两种异重流对库区及坝下的水生环境及其它水温需求有着至关重要的影响，而水库的水力学和热力学特性、泥沙运动的复杂性使得耦合模拟库区水温分层与泥沙运动极为困难，项目采用室内试验、原型观测与数值模拟相结合的技术路线，从实验与理论两方面探求了温差泥沙耦合异重流的运动规律。原型观测中通过多点监测库区的泥沙入库与异重流发展、水温分布，掌握大型深水库的水温泥沙时空分布规律；在立面二维水温、水力学模型基础上，以试验成果率定模型参数，以原型观测成果验证模型，最终建立了水温与泥沙耦合计算的水库宽度平均的立面二维温差-泥沙异重流数学模型，探寻温差与泥沙相互影响下的浮力计算模式，应用于水库水温与泥沙运动规律的关系研究中。研究表明，底层异重流会形成明显的头部较大，后端较薄的“龙头形态”。而中层或表层异重流却区别于底部异重流，其整体形态为头部较薄，而后端较厚的“楔形状”；前锋运动速度与进口的流速密切相关，若进口Re数越大，则前锋运动速度越快，反之则越慢；异重流的形成会加速环境水体在垂向的水温趋于一致。本成果对水库水温和泥沙预报理论的发展具有重要的学术意义。