【作者】 陈弘；

【导师】 高学平；

【作者基本信息】 天津大学 ， 水力学及河流动力学， 2013， 博士

【摘要】 大型水库兴建后，库内水体流动缓慢或趋于静止，形成庞大的静止水域，由于来自太阳和大气的辐射以及水体的物理性质的共同作用，形成了与天然河道不同的水温分布特性，水体在垂向呈现季节分层的现象。已建的大型水库，进水口多采用靠近水库底部的取水方式，下泄水温与下游天然河道有着显著差异，由于水库水温沿垂向的分层特性，下泄水温多偏低，故对下游河道的生态环境会造成不良影响。为保证下游河道的生态用水需要，分层取水措施正逐步应用于大型水库水电站进水口的设计中。本文主要通过物理模型试验与数值模拟相结合的方法，对大型水电站下游生态用水要求而采取的分层取水进水口的下泄水温进行研究，以糯扎渡水电站分层取水进水口为背景，研究大型水库分层取水的下泄水温，探求水库水温分层、叠梁门高度、下泄水温之间的关系，分析水库分层对取水过程的影响，探讨分层取水的取水范围与下泄水温的形成机理。最后总结下泄水温的规律，为大型水电站分层取水进水口的设计提供参考依据。主要的研究内容和成果如下：（1）总结分析了国内外水库水温分层的研究进展。介绍了水库水温分层的形成、低温下泄水对生态坏境的影响以及减免下泄低温水影响的措施，并对水库水温的预测方法和试验方法进行了介绍。（2）分析了水库水温分层取水模型试验的相似关系。依据连续性方程、运动方程和能量方程，考虑水库分层取水的流动特点，对水库水温模型相似进行了理论分析。在几何相似的前提下，保证库区弗劳德数相等和密度弗劳德数相等，得到了模型与原型下泄水温的换算关系，且正确性得到了原型观测资料的验证。（3）建立了糯扎渡水电站分层取水进水口物理模型，采用直接加热水体的方法模拟水库水温。在水库垂向水温分布已知的条件下，试验得到了典型平水年的下泄水温，分析下泄水温的变化规律，为水电站进水口的实际运行提供依据。而后，在水温分布与水位不变的情况下，研究了叠梁门高度对下泄水温的影响；在不同水库水温分布的情况下，讨论下泄水温升高幅度与水温分布间的关系；在淹没深度相同时，分析下泄水温的变化。（4）详细介绍了Flow-3D数值模型，以此为基础建立精细的进水口三维数学模型，模拟大型水库分层取水的过程，并利用物理模型试验值对其进行验证。模型能够反映进水口细部体型，且具有较高模拟精度。通过水库水温分层与水体均一情况的对比计算，分析了水温分层情况下进水口水体的流动特性。利用三维数学模型，得到进水口附近取水时流动与温度分层共同作用下的温度场和流场，分析下泄水温的形成机理；对下泄水体的主要来源进行了分析，得到了下泄水温对应水库水温分布中的位置。更多还原

【Abstract】 After the construction of a large reservoir, a large area of backwater field isformed. And because of the physical chemistry characteristics of water and thefunction of the radiation of the sunlight and the atmosphere, the water temperaturedownstream which is totally different from original river is formed and the characterof the water temperature is distribution of seasonal stratification. The meaner ofbottom withdrawal from reservoir are adopted in large reservoir. But the character ofthe stratification in reservoir and the lower water temperature released will haveharmful effects on the environment downstream. And in order to satisfy the ecologicalwater in downstream, selective withdrawal is adopted gradually in the design of thehydropower station of large reservoir.Based on the multi-level intake of Nuozhadu Reservoir, this paper mainly studiedthe water temperature released from stratification reservoir via model experiment andnumerical simulation, searched the relationship of the water stratification, the heightof stop-logs gate and the water temperature released and discussed the formation ofthe water temperature released. At last this paper summed up the disciplinarian of thewater temperature released and the results provided theoretical basis for the design ofselective withdrawal in large reservoirs. The main contents and conclusions are asfollowed:(1) A review of temperature distribution and selective withdrawal was made. Theformation of the characteristics of the stratification in reservoir, the effects oflower-temperature released on the downstream environment, and the measures ofalleviation of the effects mentioned above was introduced, and the method ofprediction and experiment was also presented.(2) Similarity relationship of water temperature experiment for selectivewithdrawal from reservoirs was analyzed. Based on continuity equation, motionequation and heat balance equation, and considering the flow features of selectivewithdrawal the similarity relationship of water temperature experiment was analyzed.In the condition of the geometry similarity, ensure the the equality of Froude numberand density Froude number in the reservoir of prototype and experiment respectively.And the relationship for conversion of water temperature between model andprototype had been proposed. And the results were consistent with those in prototype. (3) A model experiment was conducted based on multi-level intake in NuozhaduHydropower station, by heating up water directly to realize the thermal stratificationin reservoir. The water temperature released was gained via the experiment, and thevariations of the water temperature released were analyzed. On the condition of thefixedness of the water temperature distribution and water level, the variety of thewater temperature released with the height of the stop logs gate was studied; on thecondition of different water temperature distributions, the relationship of the increasescope of the water temperature released and the water temperature distribution wasdiscussed; and on the condition of the same submerge depth, the water temperaturereleased also was analyzed.(4) An comprehensive introduction of the Flow-3D model was made in the paper,and based on the model a refined3-D intake model was established to simulate theselective withdrawal. And the model results had a good agreement with that in theexperiment. The flow characteristics near the intake in case of thermal stratificationwere analyzed via the comparison of the thermal stratification and homogeneoustemperature in reservoir. The temperature field and flow field near the intake weregained. And the formation of the water temperature released and the position of thewater temperature released in the thermal stratification were analyzed.更多还原