基于PIV技术的低雷诺数下棒束通道流场研究

基于粒子图像测速(PIV)技术开展了低雷诺数(Re)条件下5×5棒束通道内充分发展段的流场可视化研究,试验Re从310～12296内选择了22组工况进行研究。试验结果表明:在低Re下,棒束通道内部的相对速度梯度较大,随着Re的上升,棒束通道内速度趋向于均匀化分布;通过阻力特性观察到的棒束通道中转捩相对于圆管较为模糊,转捩Re为900左右;在低Re效应的影响下,无量纲速度均方根随Re的增大而减小,而在转捩Re附近出现了无量纲速度均方根随Re的增大而增大的现象;此外该试验可以用于验证湍流模型对于不同Re的适用性。

Research on Flow Field in Rod Bundle Channel under Low Reynolds Number Using PIV Technique

Based on the particle image velocimetry(PIV) technique, the flow visualization in the fully developed 5×5 rod bundle channel at low Reynolds number was studied. The Reynolds number ranges from 310 to 12296. The experimental results show that the relative velocity gradient in the rod bundle channel is more significant at low Reynolds number. With the increasing of Reynolds number, the velocity distribution in the rod bundle channel tends to be uniform. The transition observed by the resistance characteristics in the rod bundle channel are more ambiguous than those in the circular tube, and the transition Reynolds number is about 900. Under the influence of low Reynolds number effect, the dimensionless RMS velocity decreases with the increasing of Reynolds number, while near the transition Reynolds number, the dimensionless RMS increases with the increasing of Reynolds number. Besides, the experimental data can be used to verify the applicability of the turbulence model to different Reynolds Numbers.