In many engineering applications, such as heating and cooling systems, flow around an automobile or building, separation and reattachment regions are formed. These regions are very important for controlling the amount of heat and mass transfer. Liquid sodium is used as heat transfer fluid in many areas having a high temperature, especially nuclear reactors. In this work, the effects of flow separation and reattachment on the heat transfer and flow properties of step corner structures with different chamfer lengths as h/4, h/2, 3 h/4 and h comparing with and without chamfer (normal) geometry have been numerically investigated in the vertically positioned backward facing step flow geometry for fast reactors that need to be cooled efficiently. One of the walls behind the backward facing step has a constant temperature while the others are adiabatic. The results of the work have been determined by solving steady conservation equations with three dimensional and k-ε turbulence model with Boussinesq approach using ANSYS-FLUENT computer program. Water and liquid sodium have been employed as working fluids. The expansion rate of the backward-facing step is 1.5. The study has been carried out at two different Reynolds numbers: 5000 and 10000. The presented work has been compared with the numerical results of the study found in the literature and it has been seen that they are compatible and acceptable with each other. The results have been exhibited as the variations of Nu number, fluid temperature, turbulence kinetic energy and pressure. Besides, temperature, velocity and streamline distributions have been visualized in backward facing step flow geometry. For Re = 10000, it has been determined that average fluid temperature increment value of the backward facing step geometry with h chamfer length in the liquid sodium flow has been 6.54 K higher than in water.

在许多工程应用中，例如加热和冷却系统，在汽车或建筑物周围流动，形成分离和重新连接区域。这些区域对于控制热量和质量传递非常重要。在许多高温区域，尤其是核反应堆中，液态钠用作传热流体。在这项工作中，流分离和重新附着对具有不同倒角长度（例如h / 4，h / 2、3 h / 4和h）的阶梯拐角结构的传热和流动特性的影响（有和没有倒角的情况下）（正常）已经对需要有效冷却的快速反应器在垂直放置的，面向后的阶梯流几何形状中进行了数值研究。向后的台阶后面的壁中的一个壁具有恒定的温度，而其他壁则是绝热的。通过使用ANSYS-FLUENT计算机程序用Boussinesq方法求解三维和k-ε湍流模型的稳定守恒方程，确定了工作的结果。水和液态钠已被用作工作流体。向后步骤的扩展率为1.5。这项研究是在两个不同的雷诺数下进行的：5000和10000。将提出的工作与文献中的研究数值结果进行了比较，发现它们彼此兼容且可以接受。结果显示为Nu数，流体温度，湍流动能和压力的变化。此外，温度，速度和流线分布已经在面向后的阶梯流几何图中可视化了。对于Re = 10000，