先进压水堆带定位格架5×5燃料棒束通道热工水力特性CFD数值模拟

The international benchmark MATiS-H with 5×5 fuel rod bundles with spacer grids was studied carefully and the best user practice guideline for the rod bundles simulation was achieved firstly. A 5×5 rod bundles CFD model with spacer grid in the advanced pressurized water reactor (APWR) was established. The effect of the spacer grid on the flow and heat transfer of the coolant in the sub-channel was studied. The velocity and temperature distribution of the coolant and the pressure drop in the sub-channel were obtained. The mixing effect of the mixing vanes was revealed. Results show that the lateral velocity in the region of spacer grids is mainly caused by the springs and dimples, while the mixing vanes have a stronger mixing effect on the coolant, resulting in the maximum lateral velocity of the coolant in the section located at the top of the mixing vanes maximum being 3.24 m/s, and the average lateral velocity is 1.44 m/s. Lateral velocity always exists in the range of 30 hydraulic diameters in the downstream of the spacer grid and gradually decreases. The coolant pressure drop in the spacer grid area increases sharply, and the mixing vanes greatly changes the coolant flow direction, resulting in the uneven coolant flow temperature distribution and enhanced heat transfer.