Abstract Wrapped wire spacers have been incorporated as the spacing device in advanced nuclear reactors such as the sodium-cooled fast reactor and supercritical water-cooled reactor. The cross flow induced by the wrapped wire affects the subchannel mixing and fuel rod temperature, which is a concerned issue in the thermal-hydraulic design of the fuel assembly. In the present paper, an experiment has been conducted to study the cross flow of subcritical water in a square channel containing a single tube which was helically wrapped by a wire using particle image velocimetry. The global velocity distribution and local flow features were obtained. It was found that the cross-sectional small vortexes are generated by the fluid-wall interaction as well as the wrapped wire. Local measurements using higher spatial resolution could capture more detailed flow characteristics compared to the global measurements. The magnitude of the secondary flow weakened along the cross-flow direction due to the blockage of the wire. The cross flow became stronger with the decrease of wire pitch, but this effect was more visible when the wire pitch is shorter than a certain limit. In addition, it was also observed that the cross-sectional velocity magnitude and special turbulent kinetic energy increase gradually with increasing Reynolds number. The spatially high-resolution experimental data combined with the simple geometry and clear boundary conditions can be used for the validation of CFD codes and models in predicting the wire-induced cross flow.

中文翻译：

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由缠绕的线间隔件引起的交叉流的 PIV 测量

摘要 在钠冷快堆、超临界水冷堆等先进核反应堆中，已采用绕包线隔板作为隔板装置。缠绕线引起的横流影响子通道混合和燃料棒温度，这是燃料组件热工水力设计中的一个关注问题。在本论文中，已经进行了一项实验，以使用粒子图像测速法研究方形通道中亚临界水的横向流动，该方形通道包含一个由金属丝螺旋缠绕的单管。获得了全局速度分布和局部流动特征。发现横截面小涡流是由流体-壁相互作用以及缠绕的线产生的。与全局测量相比，使用更高空间分辨率的局部测量可以捕获更详细的流动特征。由于导线的堵塞，二次流的大小沿错流方向减弱。横流随着线距的减小而变强，但当线距小于一定限度时，这种影响更加明显。此外，还观察到截面速度大小和特殊湍流动能随着雷诺数的增加而逐渐增加。空间高分辨率的实验数据结合简单的几何形状和清晰的边界条件，可用于验证 CFD 代码和模型，以预测导线引起的横流。由于导线的堵塞，二次流的大小沿错流方向减弱。横流随着线距的减小而变强，但当线距小于一定限度时，这种影响更加明显。此外，还观察到截面速度大小和特殊湍流动能随着雷诺数的增加而逐渐增加。空间高分辨率的实验数据结合简单的几何形状和清晰的边界条件，可用于验证 CFD 代码和模型，以预测导线引起的横流。由于导线的堵塞，二次流的大小沿错流方向减弱。横流随着线距的减小而变强，但当线距小于一定限度时，这种影响更加明显。此外，还观察到截面速度大小和特殊湍流动能随着雷诺数的增加而逐渐增加。空间高分辨率的实验数据结合简单的几何形状和清晰的边界条件，可用于验证 CFD 代码和模型，以预测导线引起的横流。但是当线距短于某个限制时，这种效果更加明显。此外，还观察到截面速度大小和特殊湍流动能随着雷诺数的增加而逐渐增加。空间高分辨率的实验数据结合简单的几何形状和清晰的边界条件，可用于验证 CFD 代码和模型，以预测导线引起的横流。但是当线距短于某个限制时，这种效果更加明显。此外，还观察到截面速度大小和特殊湍流动能随着雷诺数的增加而逐渐增加。空间高分辨率的实验数据结合简单的几何形状和清晰的边界条件，可用于验证 CFD 代码和模型，以预测导线引起的横流。