Implications concerning rod bundle crossflow mixing based on measurements of turbulent flow structure
Implications concerning rod bundle crossflow mixing based on measurements of turbulent flow structure
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DOI：
10.1016/0017-9310(74)90012-x
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发表时间：
1974-03
影响因子：
5.2
通讯作者：
D. S. Rowe;B. Johnson;J. Knudsen
中科院分区：
文献类型：
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作者：
D. S. Rowe;B. Johnson;J. Knudsen
在“干净”棒束流道中，研究了流道几何形状对充分发展湍流的影响。这些信息是为了更好地理解杆束子通道之间的交叉流动混合。实验在雷诺数为50000 ~ 200000的水中进行。实验流动模型考虑了1.25和1.125的节径比。速度轴向分量、湍流强度和欧拉自相关函数是主要测量参数。自相关函数提供了湍流主导频率的指示，并利用泰勒的假设估计了纵向宏观尺度。还获得了有限数量的横向分量湍流强度数据。实验结果表明，杆隙间距（节径比）是影响流动结构最显著的几何参数。减小杆隙间距增加了湍流强度、纵向宏观尺度和湍流主导频率。这些湍流参数对雷诺数不敏感。结果表明，在杆隙附近存在宏观流动过程。这包括二次流，当杆隙间距减小时，流动脉动的规模和频率增加。当用交叉流混合解释时，结果与目前的交叉流混合相关性一致。
An experimental study was performed to investigate the effect of flow channel geometry on fully developed turbulent flow in “clean” rod bundle flow channels. This information was sought to obtain a better understanding of crossflow mixing between rod bundle subchannels. The experiments were performed in water with a Reynolds number range from 50 000 to 200 000. The experimental flow models considered pitch-to-diameter ratios of 1.25 and 1.125. Axial components of velocity, turbulence intensity and Eulerian autocorrelation function were the primary measurements. The autocorrelation function provided an indication of the dominant frequency of turbulence and an estimate of the longitudinal macroscale by using Taylor's hypothesis. A limited amount of lateral component turbulence intensity data was also obtained.The experimental results show that rod gap spacing (pitch-to-diameter ratio) is the most significant geometric parameter affecting the flow structure. Decreasing the rod gap spacing increases the turbulence intensity, longitudinal macroscale, and the dominant frequency of turbulence. These turbulence parameters are rather insensitive to Reynolds number.The results indicate that macroscopic flow processes exist adjacent to the rod gap. This includes secondary flows and increased scale and frequency of flow pulsations when the rod gap spacing is reduced. When interpreted in terms of crossflow mixing, the results are consistent with present crossflow mixing correlations.