板翅式换热器入口结构内流场的数值模拟

Numerical and experimental investigation of inside flow patterns of the entrance configuration in plate-fin heat exchanger

利用PIV粒子图像测速仪和CFD数值模拟的方法,对板翅式换热器入口结构改进前后的流场进行实验测量和数值计算.获得入口结构内部不同剖面处的流场分布图,发现了流场的流动与分布规律.由于原始入口结构的不合理导致漩涡、回流等现象存在,使得其内部轴向以及径向的物流分配极不均匀.而对于在入口结构1/2高度处添加开孔分流板的改进型结构,不仅在换热器入口结构长度方向(z方向)上,而且在所测截面的y方向,物流分配的均匀性有了很大改善,流场分布更加合理.而且,实验结果和数值模拟结果相符合.

Conventional and improved entrance configurations in plate-fin heat exchangers were measured experimentally and computed numerically by using particle imaging velocimetry （PIV） experiments and computational fluid dynamics （CFD） simulations. The difference inside flow patterns were obtained at different cross sections in the entrance configurations under similar conditions. A series of velocity vector and streamline graphs of different cross-sections were given. The numerical and experimental results indicate that performance of fluid maldistribution in conventional entrance configuration was very serious. However, the improved header configuration with punched baffle can effectively improve the uniformity of fluid flow distribution in both radical （y-direction） and axial directions （z-direction）. The numerical results and the experimental data are in good agreement with each other.