燃料组件5×5格架多跨模型 CFD 模拟方法研究

摘要

The simplification of geometry ,the generation of grid and the method of post processing of 5 × 5 rod bundles in a typical fuel assembly were discussed in detail .The influence of spring and arches on pressure drop and mixing characteristics was simulated using 5 × 5 rod bundles with one span model and the interaction between multiple grids was calculated using 11-span 5 × 5 rod bundles without spring and arches .The simula-tion results indicate that spring and arches may enhance lateral flow and heat transfer with the increase of Nu 8% .However ,the pressure drop caused by spring and arches is 40% larger than that of the simplified model without spring and arches .Flow features and heat transfer characteristics across grids were obtained using the 5 × 5 multi-span model w hich can be used as CFD analysis reference of thermal-hydraulic characteristics in the fuel assembly design development and prediction of DNB .%本文详细描述了某典型燃料组件5×5格架模型C FD分析的几何模型简化、网格划分、求解及后处理等过程。在5×5结构单跨模型上研究了弹簧刚突对搅混特性及压降的影响，并采用简化弹簧刚突的5×5格架模型实现了包含11层格架的多跨模型计算。单跨模型计算结果表明，弹簧刚突结构强化了横向流动，利于换热，Nu提高了8％，但弹簧刚突格架模型较简化弹簧刚突模型压降损失增加了40％。多跨模型计算得到了多层格架全程流动换热特性，为燃料组件自主研发中定位格架数量及布置的设计优化以及DNB预测计算提供了有效的CFD分析方法。