Effect of Orientation and Aspect Ratio of an Internal Flat Plate on Natural Convection in a Circular Enclosure
Effect of Orientation and Aspect Ratio of an Internal Flat Plate on Natural Convection in a Circular Enclosure
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DOI：
10.3390/pr7120905
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发表时间：
2019-12
期刊：
影响因子：
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通讯作者：
Anjie Wang;Cunlie Ying;Yingdong Wang;Lijun Yang;Yunjian Ying;Lulu Zhai;Wei Zhang
中科院分区：
文献类型：
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作者：
Anjie Wang;Cunlie Ying;Yingdong Wang;Lijun Yang;Yunjian Ying;Lulu Zhai;Wei Zhang
本文对Ra = 106时具有内平板的圆形封闭腔内的自然对流进行了数值研究。将平板的横截面积固定为H·W/D2 = 0.01、0.04和0.09三个值，其中H和W为平板的高度和宽度，D为外壳的直径，而纵横比变化，使平板垂直放置（H > W）或水平放置（H < W）。研究了平板的方向和长宽比对自然对流换热特性的影响。数值结果表明，竖直放置的平板总传热率较高，且随横截面积的增大而增大;而水平放置的平板，尤其是横截面积较大的平板，其宽度几乎没有影响。根据方向和纵横比，在板的每一侧可以有一个主涡、一个主涡和一个次涡、或一个次涡和两个分离的涡，并且热羽流结构可能出现在板的尖锐顶角处。因此，外壳和板表面上的局部热传递受到影响。协同分析表明，流体循环的传热强化作用在涡的中心和涡与涡之间的边界处最为显著。
This work presents a numerical investigation on natural convection in a circular enclosure with an internal flat plate at Ra = 106. The cross-section area of the plate was fixed at three values, H·W/D2 = 0.01, 0.04, and 0.09, in which H and W are the height and width of the plate and D is the diameter of the enclosure while the aspect ratio changes, which makes the plate vertically placed (H > W) or horizontally placed (H < W). The objective of this work was to explore the effects of the orientation and aspect ratio of the plate on the characteristics of natural convection in various aspects. The numerical results reveal that the overall heat transfer rate is higher for the vertically placed plate and increases with the cross-section area, while the width of the plate has almost no effect for the horizontally placed plate, especially for the plate with a relatively large cross-section area. Depending on the orientation and aspect ratio, there can be one primary vortex, one primary and one secondary vortex, or one secondary and two separated vortices to each side of the plate, and the thermal plume structure may appear at the sharp top corners of the plate. Consequently, local heat transfer on the surfaces of the enclosure and plate is affected. Synergy analysis reveals that the enhancement of heat transfer from the fluid circulation is the most significant at the center of the vortices and at the boundary between them.