Abstract In nuclear fuel assembly mixing vanes are fabricated on the spacer grids to promote diversion cross flow and turbulent mixing. In order to investigate the decay of diversion cross flow and turbulent mixing induced by the split mixing vanes, particle image velocimetry (PIV) measurement is carried out to acquire high-fidelity flow field data in a 5 × 5 rod bundle with mixing vane spacer grid. Intensities of turbulence, secondary and cross flow, inter-subchannel mixing are obtained based on the experimental data and fitted as exponential functions of normalized distance from the spacer grid. Two decay phases are identified from the experiments. A blending function is introduced to unify the near-wake and far-wake decay functions of turbulent mixing intensity. Based on the measured differential pressure between neighboring subchannels, a correlation of cross-flow pressure loss coefficient Kg is proposed, i.e. K g ∝ I cf - 1.09 .

中文翻译：

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压水堆燃料组件分流混合叶片强制混合实验研究

摘要 在核燃料组件中，在隔栅上制作混合叶片以促进导流错流和湍流混合。为了研究分流混合叶片引起的导流横流和湍流混合的衰减，进行粒子图像测速（PIV）测量以获取具有混合叶片间隔网格的 5 × 5 棒束中的高保真流场数据. 湍流、二次流和交叉流的强度、子通道间混合是基于实验数据获得的，并拟合为距间隔网格的归一化距离的指数函数。从实验中确定了两个衰变阶段。引入混合函数来统一湍流混合强度的近尾流和远尾波衰减函数。基于测得的相邻子通道之间的压差，