A PIV study of the laminar axisymmetric sudden expansion flow
A PIV study of the laminar axisymmetric sudden expansion flow
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DOI：
10.1007/s003480050288
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发表时间：
1999-02
影响因子：
2.4
通讯作者：
K. Hammad;M. Otugen;E. Arik
中科院分区：
文献类型：
--
作者：
K. Hammad;M. Otugen;E. Arik
采用实时数字粒子图像测速技术对轴对称突扩段层流流动进行了实验研究。研究选择的膨胀比（下游与上游管道直径比）为2。测量涵盖了分离、再附着和再发育的区域。根据上游管道直径和体积流速，在20和211之间的六个雷诺数下，在垂直中心平面上获得二维速度图。流函数分布的计算和提出的流向和径向速度图。确定了再附着长度、再发展长度和回流强度对雷诺数的依赖关系。结果表明，无论是再附着长度还是再附着下游的再发展长度都是雷诺数的线性函数。另一方面，回流涡流强度对雷诺数有非线性依赖关系，随着雷诺数的增加，回流涡流强度变得较弱。结果表明，没有不稳定或浮力驱动的流动不对称的范围内20？是吗？211.
The laminar flow through an axisymmetric sudden expansion was investigated experimentally using real-time digital particle image velocimetry. An expansion ratio (downstream-to-upstream pipe diameter ratio) of 2 was selected for the study. The measurements covered the regions of separation, reattachment and re-development. Two dimensional velocity maps were obtained on the vertical center plane for six Reynolds numbers between 20 and 211, based on the upstream pipe diameter and bulk velocity. The stream function distributions are calculated and presented from the streamwise and radial velocity maps. The dependence of reattachment length, redevelopment length and recirculating flow strength on the Reynolds number are determined. Results show that not only the reattachment length but also the redevelopment length downstream of reattachment is a linear function of the Reynolds number. The recirculation eddy strength, on the other hand, has a non-linear dependence on the Reynolds number which becomes weaker as the Reynolds number is increased. The results indicate no instability- or buoyancy-driven flow asymmetry in the range 20?Re? 211.