温度分层型水库分层取水口流动规律及取水水温研究

For thermally stratified reservoirs, the temperature of water withdrawn from different layer is of great difference. If the intake is at a fixed position, e.g. a deep water intake, the temperature of water withdrawn is always cold, and induces the negative effect on the growth of corps and the environments in downstream reach. The multi-level withdrawal is an effective way to control withdrawal water temperature and usually adopted to get desired water temperature. So the flow mechanism and the effect of temperature control at the intake are the issues urgent to be studied, because thermally stratified fluid is different from homogeneous fluid. In this work, the research methods of model experiment, 3D numerical simulation and theoretical analysis are adopted simultaneously. The multi-level withdrawal of different intake structures in thermally stratified reservoirs, such as multi-level intakes and floating point intakes, are studied comprehensively. The flow characteristics and the effects of temperature control at intakes are studied, the flow law at intakes and the flow moving process in stratified water are elucidated, the range affected by withdrawal, the parameters affecting withdrawal temperature and the temperature control mechanism of water intakes are put forward, and the relationship among withdrawal temperature, withdrawal flux and temperature distribution in the reservoir are proposed. The method of simulating water temperature distribution directly is used in this work, which is more reliable than the previous method simulating two-layer stratification using salt and fresh water. The flow law at intake considering the effect of water temperature stratification is different from that in the homogeneous fluid. The results can be directly applied to the design and operation of reservoir selective withdrawal.

对于水温分层型水库，沿水深水温不同，若取水口位置固定，例如深层取水口，所取水体温度较低，用于灌溉将影响作物产量和质量，泄入下游河段将影响鱼类生存环境。分层取水是获得理想水温的有效手段，鉴于温度分层水体有别于均质水体，取水口附近的流动机制、取水水温控制等亟待研究。本项目采用试验模拟、数值模拟、理论分析相结合的方法，针对温度成层型水库，以典型的多层取水口和浮式管型取水口为对象，进行取水口附近流动特性及取水水温控制效果的研究，揭示温度成层分布条件下取水口附近的流动规律、库内各层水体的运移过程，阐明取水口取水影响范围、影响取水效果的因素和取水水温控制机制，提出取水水温和取水口位置、取水量、库内水体水温分布等之间的关系。本项目试验直接模拟多层水温分布较以往的盐淡水两层模拟更符合实际，考虑温度分层水体的取水口流动规律更能揭示取水水温的控制机制，研究成果可用于水库分层取水的设计和运行管理。

对于水温分层型水库，分层取水是获得理想水温的有效手段，鉴于温度分层水体有别于均质水体，取水口附近的流动、取水水温等亟待研究。本项目采用试验模拟、数值模拟、理论分析相结合的方法，以典型的多层孔型取水口和浮式管型取水口为例，研究取水口附近流动特性及取水水温，揭示温度成层分布取水口附近流动规律，阐明取水口取水影响范围、影响因素和取水水温控制机制，提出取水水温和取水口位置、取水量、水温分布等之间的关系。.多层孔型取水口，取水口淹没深度越小，取水水温越高，水库表层与底层水温温差越大，取水水温提高幅度越大。增大取水流量可取到更上层的水体，取水水温有所提高但幅度较小。水温分层分布与水温均一分布相比，取水口前流场存在明显的差异，表底水温梯度越大，差异越明显。取水口附近取水牵引作用大于浮力作用，远离取水口，牵引作用减弱，浮力作用相对增加。水温梯度致使取水口取水范围得到一定程度集中，垂向取水范围受到一定的抑制。浮式管型取水口，取水口淹没深度是控制取水水温的主要因素，取水口淹没深度增大取水水温随着降低。取水流量对取水水温起到调节效果，取水水温随着取水流量的增加而提高。取水水温变化幅度，不仅与取水口淹没深度有关，还与水库水温分布有关。浮式取水口附近，水温均一和水温分层的流速分布存在差异，且随取水流量和淹没深度的增大而减小。水库水温均一分布时，远离取水口中心，牵引力作用影响逐渐减弱，断面流速趋向均匀。水库水温分层时，在靠近取水口断面，取水牵引力占主导作用，浮力作用较弱，随着远离浮式取水口距离的增加，水体受取水牵引力作用逐渐减弱而逐渐受浮力作用趋向稳定。.以往取水口附近流动规律是在均一水温条件获得的，本项目考虑水温分层对取水口流动的影响，丰富了水力学分层流领域的成果，在水库分层取水方面形成系统的成果。研究成果为取水设施的设计及运行管理提供技术支撑。