底流消能工水流结构区气体迁移扩散试验研究

发布时间：2018-04-27 21:12

本文选题：底流消能工 + 掺气浓度　；参考：《昆明理工大学》2017年硕士论文

【摘要】：我国许多大坝工程为70m以上的高坝、超高坝,其泄洪流量、泄洪功率,掺气消能等工程特性与中低坝有着很大的不同,并且近年一些高坝、超高坝水利水电工程采用新型消能工带来的气体超饱和和气蚀问题较为突出,更为重要的是我国已建、在建和待建水利水电工程的环境影响评价中,尚没有对其坝下游河流水体溶解气体超饱和影响进行系统深入的评价。底流消能工作为传统的一种消能方式,研究其水流结构下气体迁移扩散特性,能为其他水流流体结构下气体迁移、扩散、释放机理及不同水流流体结构下气体的运动机理提供重要依据,为降低下游水体总溶解气体的浓度,从而保护河流水生态和水环境奠定理论基础。底流消能工下,高速水流下泄进入消力池,与消力池内水体存在强烈的紊动,形成掺气水流,气泡不断发生聚并、分裂和上升现象,水体与气泡间进行交换,气泡贡献了气体传输动量的大部分,伴随有大量的机械能损失。大量的空气掺混,使消力池内水深增加,还会引起水流附加紊动扩散,对消力池内流速和压强的分布有一定的影响。因此掺气水流的研究对底流消能工体型的优化设计具有重要意义。本文是基于国家自然科学基金《高坝泄洪消能不同水流结构下气体迁移扩散运动机理研究》(项目编号:51669007)而立题,采用水工模型试验与理论分析相结合的方式,对底流消能工消力池内水体进行分区,实测了在不同入池能量、尾坎高度、掺气量下消力池底板时均压强及不同水流结构区流速和掺气浓度值,采用单一变量法,分析各水力条件对流速和时均压强分布规律、掺气浓度的分布规律及气体迁移扩散运动规律的影响。
[Abstract]:Many dam projects in China are high dams with a height of more than 70 m, super-high dams, their flood discharge, flood discharge power, aeration energy dissipation and other engineering characteristics are quite different from those of middle and low dams, and in recent years, some high dams have been built. The problem of gas supersaturation and cavitation erosion caused by the new energy dissipator in super high dam water conservancy and hydropower project is more prominent. What is more important is the environmental impact assessment of the water conservancy and hydropower project that has been built and is under construction in our country. The effect of dissolved gas supersaturation on the river water in the lower reaches of the dam has not been systematically and thoroughly evaluated. The bottom flow energy dissipation works as a traditional energy dissipation method. The characteristics of gas migration and diffusion under the flow structure are studied, and it can be used to transfer and diffuse the gas under the structure of other flow fluids. The release mechanism and the gas movement mechanism under different flow fluid structure provide important basis for reducing the concentration of the total dissolved gas in the downstream water body and thus protecting the river water ecology and water environment. Under the condition of bottom flow energy dissipator, the high speed water flow flows into the stilling pool, and there is strong turbulence with the water body in the stilling pool, which forms the aerated water flow, resulting in the accumulation, splitting and rising of the bubbles, and the exchange between the water and the bubbles. Bubbles contribute most of the momentum of the gas transport, accompanied by a large amount of mechanical energy loss. A large amount of air mixing can increase the depth of water in the stilling pool and cause the additional turbulent diffusion of the flow, which has a certain effect on the distribution of velocity and pressure in the stilling pool. Therefore, the study of aerated flow is of great significance to the optimization design of bottom flow energy dissipators. This paper is based on the National Natural Science Foundation of China, "study on the mechanism of gas migration and diffusion under different flow structures of flood discharge and energy dissipation in high dams" (item No.: 51669007), and adopts the method of combining hydraulic model test with theoretical analysis. In this paper, the water body in the energy dissipation pool of the bottom flow dissipator is partitioned. The average pressure of the bottom plate of the stilling pool, the velocity of flow and the concentration of air in the different flow structure area are measured under the different inlet energy, the height of the cauldron and the aeration volume. The single variable method is used to measure the average pressure of the bottom plate of the stilling pool. The effects of hydraulic conditions on the distribution of velocity and time-averaged pressure, the distribution of aeration concentration and the movement of gas migration and diffusion are analyzed.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV135.2

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