ABSTRACT

A steam generator is one of the essential components in Pressurized Water Reactors. One of its critical design issues is to prevent heat transfer tube damage caused by corrosion and flow-induced vibration. When designing a U-tube bundle of steam generators, a thermal hydraulic simulation code is used to predict velocity and density distribution along tubes, especially porous-media-based code, from the viewpoint of computational cost. The code first calculates a control-volume-averaged velocity. A mass conservation equation converts it to the area-averaged mixture volumetric flux at the smallest gap between two tubes. Then, the area-averaged mixture volumetric flux is converted to the local interfacial velocity at the center of the sub-channel using an interfacial velocity correlation. Comparison between measured and calculated interfacial velocities ensures the validity of the simulation code. The validation process for the code requires an interfacial velocity correlation. This study shows the newly developed interfacial velocity correlation applicable to two-phase flow in a tube bundle with a square array. The prediction uncertainty of the correlation is +6.7% (bias) ± 24.2% (random error). The correlation based on an analytical equation suggests that the correlation has good scalability to apply to a wide range of flow and geometrical parameters.

摘要

蒸汽发生器是压水反应堆的重要组成部分之一。其关键设计问题之一是防止由腐蚀和流动引起的振动引起的传热管损坏。在设计 U 型管束蒸汽发生器时，从计算成本的角度来看，热工水力模拟代码用于预测沿管的速度和密度分布，尤其是基于多孔介质的代码。该代码首先计算控制体积平均速度。质量守恒方程将其转换为两个管之间最小间隙处的面积平均混合物体积通量。然后，使用界面速度相关性将面积平均混合物体积通量转换为子通道中心的局部界面速度。测量和计算的界面速度之间的比较确保了模拟代码的有效性。代码的验证过程需要界面速度相关性。这项研究表明新开发的界面速度相关性适用于具有方形阵列的管束中的两相流。相关性的预测不确定性为 +6.7%（偏差）±24.2%（随机误差）。基于解析方程的相关性表明，该相关性具有良好的可扩展性，适用于广泛的流动和几何参数。相关性的预测不确定性为 +6.7%（偏差）±24.2%（随机误差）。基于解析方程的相关性表明，该相关性具有良好的可扩展性，适用于广泛的流动和几何参数。相关性的预测不确定性为 +6.7%（偏差）±24.2%（随机误差）。基于解析方程的相关性表明，该相关性具有良好的可扩展性，适用于广泛的流动和几何参数。