Scaling of the puffing Strouhal number for buoyant jets and plumes
Scaling of the puffing Strouhal number for buoyant jets and plumes
复制标题
浮力射流和羽流的膨胀斯特劳哈尔数的缩放
DOI：
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发表时间：
2019
影响因子：
3.7
通讯作者：
P. Hamlington
中科院分区：
文献类型：
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作者：
N. Wimer;C. Lapointe;J. Christopher;Siddharth P. Nigam;Torrey R. S. Hayden;Aniruddha A. Upadhye;M. Strobel;G. Rieker;P. Hamlington
先前的研究表明，浮力射流和羽流的“喷发”频率取决于入口处动量和浮力通量的平衡，如理查森数参数化。实验表明，膨化的斯特劳哈尔数和入口理查森数之间存在比例关系，但当特征长度取直径（对于圆形入口）或宽度（对于平面入口）时，需要几何特定关系。与早期对矩形浮力射流和羽流的研究类似，在本研究中，我们使用入口的水力半径作为特征长度，以获得跨越三个数量级的各种入口几何形状的单一斯特劳哈尔-理查森比例关系。特别是，我们使用自适应网格数值模拟来计算圆形、矩形（具有三种不同长宽比）、三角形和环形高温浮力射流和羽流在理查森数范围内的膨胀斯特劳哈数。然后，我们将这些结果与圆形、平面和矩形浮力射流和羽流的先前实验数据相结合，提出一种新的比例关系，该关系描述了各种入口形状的抽吸斯特劳哈尔数和跨越四个数量级的水力理查森数。这种基于经验的比例关系也被证明与先前的全局线性稳定性分析结果非常一致。
Prior research has shown that buoyant jets and plumes ‘puff’ at a frequency that depends on the balance of momentum and buoyancy fluxes at the inlet, as parametrized by the Richardson number. Experiments have revealed the existence of scaling relations between the Strouhal number of the puffing and the inlet Richardson number, but geometry-specific relations are required when the characteristic length is taken to be the diameter (for round inlets) or width (for planar inlets). Similar to earlier studies of rectangular buoyant jets and plumes, in the present study we use the hydraulic radius of the inlet as the characteristic length to obtain a single Strouhal–Richardson scaling relation for a variety of inlet geometries over Richardson numbers that span three orders of magnitude. In particular, we use adaptive mesh numerical simulations to compute puffing Strouhal numbers for circular, rectangular (with three different aspect ratios), triangular and annular high-temperature buoyant jets and plumes over a range of Richardson numbers. We then combine these results with prior experimental data for round, planar and rectangular buoyant jets and plumes to propose a new scaling relation that describes puffing Strouhal numbers for various inlet shapes and for hydraulic Richardson numbers spanning over four orders of magnitude. This empirically motivated scaling relation is also shown to be in good agreement with prior results from global linear stability analyses.