过渡流下叉排圆柱列的可视化实验研究

摘要

The study attempted to provide theoretical reference for the design and optimization of compact heat exchanger by investigating the flow characteristics of the offset cylinder arrays in transitional flow state.The twodimensional particle image velocimetry (PIV) was adopted in visualization experiments.This research mainly focuses on offset cylinder arrays models in different transverse spacing (Ps/D =2,3,4,5,6) and different Reynolds number (Re =120,150,200) in the condition that longitudinal spacing is particular (PT =2.5D).The results show that Re and Ps have different impact on the flow characteristics of this model.With the increase of Ps,rectifying effect caused by the downstream cylinders gradually weakens in the case of constant Re.With the increase of Re,rectifying effect becomes weaker in the case of constant Ps.The acceleration effect strengthens firstly and then weakens in each Ps in the case of constant Re,which shows the characteristic of speed recovery.With the increase of Ps,the acceleration effect on downstream cylinders inflow velocity gradually strengthens.%为了保证缩小管径后的换热器空气侧换热性能良好,研究过渡流下不同雷诺数(Re=120,150,200),不同横向间距(P=2D,3D,4D,5D,6D)的叉排圆柱列的流动特性,采用PIV二维粒子图像测速系统对过渡流下不同工况的叉排圆柱列进行可视化实验研究.结果表明,Ps及Re的变化对上游和下游圆柱的涡量场、速度相关量有不同的影响.Re一定时,随着Ps的增大,下游对上游的整流作用逐步削弱.Ps一定时,随着Re的增大,整流效果越来越不明显.Re一定时,每组Ps下的速度比值曲线都呈现出“速度恢复”现象.并且随着Ps的增加,上游圆柱对下游圆柱来流速度所起到的加速效果逐步加强.