环形掺气坎下部水气两相流特性及其作用机理研究

项目名称： 环形掺气坎下部水气两相流特性及其作用机理研究

项目编号： No.51509123

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 水利工程

项目作者： 南军虎

作者单位： 兰州理工大学

项目金额： 20万元

中文摘要： 泄洪洞竖井内的环形掺气坎是不同于传统掺气技术的新创意，其不仅具有掺气减蚀的作用，而且可改善水流流态并增加水流的消能率，但对其下部水气两相流特性及其作用机理等问题缺乏研究，这些问题是该类掺气技术得到推广应用需要解决的关键技术问题。在前期试验研究基础上，项目拟采用数值模拟、试验研究和理论分析相结合的方法，深入研究环形掺气坎下部水气两相流的流态、压力、掺气浓度、空腔长度、消能率等水力特性，揭示水气混掺机理、能量耗散机理、水流脉动特性和壁面掺气减蚀特性，分析模型通风量、掺气浓度、空腔长度、空腔负压等水力参数的缩尺效应；在此基础上提出将环形掺气坎应用至大落差调水工程竖井中的设想，并从工程的安全性和经济性角度评估其消能、减压、流态优化效果。本项目的研究有利于丰富掺气减蚀技术，可为环形掺气坎在高水头泄洪建筑物和大落差调水工程等工程中的应用提供理论依据，具有重要的科学意义与应用基础研究的价值。

中文关键词： 环形掺气坎；水气两相流；水力特性；作用机理；缩尺效应

英文摘要： The use of an annular aerator placing in the vertical shaft of flood discharge tunnel is a new engineering idea, and is different from the traditional ones. It not only has the aeration effect, but also can improve the flow pattern and increase the energy dissipation ratio. However, the hydraulic characteristics of water-air two-phase flow in the lower zone and the working mechanism of annular aerator have not been researched, which is a key to the popularization and application of this new type of technology. Based on the previous experimental researches, the hydraulic characteristics of water-air two-phase flow in the lower zone of the annular aerator, such as flow pattern, pressure, ventilation, aeration, cavity length and energy dissipation in two-phase flow, and etc., were studied by numerical simulation, model test and theoretical analysis. The mixing mechanism of water and air, mechanism of energy dissipation, fluctuation characteristics of the flow and reduction of cavitation erosion on the tunnel wall were reveled. The model scale effect of ventilation, aeration and cavity length was analyzed. On the basis of those studies the assumption of applying the annular aerator to large drop height water transfer project was posed, and the effect of energy dissipation, decompression and flow optimization were estimated from the point view of ecological environment and economic benefit. The project research results are beneficial to enrich air entrainment technology and can provid the theoretical basis for application of annular aerator in discharge tunnel with high water head and water transfer project in case of large drop height, and have great significance and value to the basic application research in academic.

英文关键词： annular aerator;water-air two-phase flow;hydraulic characteristics;working mechanism;scale effect