冷却剂与含格架燃料棒束多场耦合分析

燃料棒束作为压水堆燃料组件的组成部分，其热工和结构特性直接关系到反应堆的安全。本文利用ANSYS WORKBENCH软件分析了冷却剂在5×5含定位格架燃料棒束通道内流动的分布，采用冷却剂与燃料棒束多场耦合的方式研究了燃料棒束的流动传热特性和结构形变特性。结果表明：定位格架扰动冷却剂形成横向二次流并在下游棒束间形成绕流；多场耦合条件下二次流峰值速度和平均速度均小于单流场的；二次流与燃料棒的热应力使棒束发生形变，功率和流动分布的不均匀导致形变在轴向和径向的不均匀；相较于无格架情况，定位格架的存在使冷却剂的搅混流动更加明显，冷却剂对燃料棒冲击增大；在有、无定位格架两种情况下棒束形变均很小，可保持原本结构的稳定。

Multi-field Coupling Analysis on Coolant and Fuel Rod Bundle with Grid Spacer

Fuel rod bundle is a component of fuel assembly in pressurized water reactor (PWR), whose thermal and structural characteristics are directly related to reactor safety. In this paper, the distribution of coolant flow in the 5×5 fuel rod bundle with grid spacer was analyzed by using ANSYS WORKBENCH software. The flow and heat transfer characteristics and structural deformation characteristics of fuel rod bundle were studied by the way of multi-field coupling between coolant and fuel rod bundle. The simulation results show that the grid spacer disturbs the coolant to form the transverse secondary flow and the flow around the downstream rod bundle. The peak and average velocities of multi-field coupling secondary flow are less than that in single flow field. Secondary flows and thermal stress cause rod bundle deformation, and the uneven power and flow distribution result in the axial and radial nonuniform deformation. Compared with only rod bundle, grid spacer makes the mixing flow notable, which increases the impact on fuel rods. The deformation of rod bundle is very small in situations with and without grid spacer, and rod bundle can maintain stability of its original structure.