Experimental and computational studies of two-phase flows in nuclear reactor systems

在热交换器、核反应堆部件和其他发生沸腾或冷凝的设备中，通常会遇到气体和液体的混合物。这种流动非常复杂，但测量技术和计算方法的最新进展使人们能够深入研究它们的特征。该项目的目的是应用和进一步发展现有的实验和计算流体动力学（CFD）方法来研究CANDU核电站中使用的类型的头部-馈电系统的两相流动特性。主要的实验任务是：i)通过增加一个通用的集水头/进水器模型来修改现有的空气-水流动回路，其中可以选择不同的主动进水塔和主动进水器组合；Ii)建立该模型给料管内气体和液体流速测量数据库，同时记录转塔入口条件和封头内的流动模式；(3)评价给料管内流动障碍对气液流速的影响。计算分析的主要任务是在与实验相同的进口流动条件和相同的几何形状下对空气-水流动进行CFD模拟，并将模拟结果与测量结果进行比较，以验证CFD作为一种工具在核安全分析感兴趣的条件和几何形状下进行两相流动模拟的适用性。拟议的实验和数值调查将使用最先进的工具进行，并将提高核反应堆设计者和安全分析人员的技术能力。它们直接支持AECL空气-水集箱设备测试。它们还将协助加拿大核动力工业验证和改进现有的多阶段分析工具，并在世界经济的这一领域保持竞争地位。这笔拨款将使渥太华大学能够对几名学生和其他人员进行核反应堆热水学方面的教育，从而为核工业提供一批有前途的高技能研究工程师，以取代目前退休的这一代人员。

Mixtures of gas and liquid flows are commonly encountered in heat exchangers, in components of nuclear reactors and other equipment in which boiling or condensation occurs. Such flows are very complex, but recent advances in measurement techniques and computational methods have permitted an in-depth examination of their characteristics. The objective of this project is to apply, and further develop, available experimental and computational fluid dynamics (CFD) methods to the study of two-phase flow characteristics in header-feeder systems of the type used in CANDU nuclear power plants. The main experimental tasks are: i) to modify an existing air-water flow loop by the addition of a versatile header/feeder model, in which different combinations of active inlet turrets and active feeders can be selected; ii) to assemble a database of measurements of gas and liquid flow rates in the feeder tubes of this model, while also documenting the turret inlet conditions and the flow patterns inside the header; and iii) to assess the effect of flow obstructions inside feeder tubes on the gas and liquid flow rates. The main task of the computational analysis is to perform CFD simulations of air-water flows at the same inlet flow conditions and in the same geometries as those of the experiments and to compare the simulation results to the measurements to verify the applicability of CFD as a tool for two-phase flow simulation at conditions and geometries of interest to nuclear safety analysis. The proposed experimental and numerical investigations will be conducted using state-of-the-art tools and will advance the technical capabilities of nuclear reactor designers and safety analysts. They are in direct support of the AECL air-water header facility tests. They will also assist the Canadian nuclear power industry in validating and improving existing multi-phase analytical tools and in maintaining a competitive position in this field of the world economy. This grant will enable uOttawa to educate several students and other personnel in nuclear reactor thermalhydraulics, thus providing the nuclear industry with a pool of prospective highly skilled research engineers to replace the currently retiring generation of such personnel.