Separating and Reattaching Flow Structure in a Suddenly Expanding Rectangular Duct
Separating and Reattaching Flow Structure in a Suddenly Expanding Rectangular Duct
复制标题
突然膨胀的矩形管道中的分离和重新连接流动结构
DOI：
10.1115/1.2816809
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发表时间：
1995
影响因子：
2
通讯作者：
M. Otugen
中科院分区：
文献类型：
--
作者：
G. Papadopoulos;M. Otugen
对矩形通道内后台阶的不可压湍流流动进行了实验研究。侧壁对核心流的影响是通过改变长宽比（定义为台阶的跨度与高度的比）从1到28来确定的。基于台阶高度和迎面而来的自由流速度的雷诺数为26，500。详细的速度测量，包括湍流应力，在一个区域延伸过去的流动再附着区。还测量了台阶壁和平坦壁上的壁静压。此外，在分离流周围的所有四壁上获得表面可视化，以补充近壁速度测量。结果表明，即使在相对较大的展弦比下，展弦比对速度和壁面压力都有影响。例如，在再附着下游的再开发区域中，恢复压力随着较小的展弦比而减小。三维侧壁效应往往会减缓下游的再附着的松弛较小的长宽比证明了由速度场的演变。对于所研究的两个最小展弦比，获得了更高的中心面流向和横向速度，这表明沿着管道的整个跨度存在三维平均流结构。«少
The incompressible turbulent flow over a backward-facing step in a rectangular duct was investigated experimentally. The side wall effects on the core flow were determined by varying the aspect ratio (defined as the step span-to-height ratio) from 1 to 28. The Reynolds number, based on the step height and the oncoming free-stream velocity was 26,500. Detailed velocity measurements were made, including the turbulent stresses, in a region which extended past the flow reattachment zone. Wall static pressure was also measured on both the step and flat walls. In addition, surface visualizations were obtained on all four walls surrounding the separated flow to supplement near-wall velocity measurements. The results show that the aspect ratio has an influence on both the velocity and wall pressure even for relatively large aspect ratios. For example, in the redevelopment region downstream of reattachment, the recovery pressure decreases with smaller aspect ratios. The three-dimensional side wall effects tend to slow down the relaxation downstream of reattachment for smaller aspect ratios as evidenced by the evolution of the velocity field. For the two smallest aspect ratios investigated, higher centerplane streamwise and transverse velocities were obtained which indicate a three-dimensional mean flow structure along the full span ofmore » the duct.« less