Aspect ratio dependence of Rayleigh–Bénard convection of cold water near its density maximum in vertical cylindrical containers
Aspect ratio dependence of Rayleigh–Bénard convection of cold water near its density maximum in vertical cylindrical containers
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DOI：
10.1016/j.ijheatmasstransfer.2016.03.016
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发表时间：
2016-06
影响因子：
5.2
通讯作者：
Yupeng Hu;You-Rong Li;Chun-Mei Wu
中科院分区：
文献类型：
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作者：
Yupeng Hu;You-Rong Li;Chun-Mei Wu
本文介绍了一组实验和数值计算结果的Rayleigh-Bénard对流的冷水在其密度最大值附近的垂直圆柱形容器具有不同的纵横比，定义为比的直径高度的容器。测量了底部热壁的平均努塞尔数，并详细讨论了密度反演参数、长宽比和瑞利数的影响。结果表明，不同流型下存在不同的局部Nusselt数分布，平均Nusselt数随密度反演参数的增大而减小。密度反演参数对传热的负面影响在高瑞利数值时变得更加显著。高宽比的增加可以增强Rayleigh-Bénard对流的换热。但是，增强效果随着纵横比的增加而逐渐降低。此外，在大的纵横比，多辊流动模式出现，辊的数量随着纵横比的增加。根据实验数据，在可接受的不确定度范围内得到了换热能力的经验关联式。
This paper presents a set of experimental and numerical results on the Rayleigh–Bénard convection of cold water near its density maximum in vertical cylindrical containers with different aspect ratio that is defined as the ratio of the diameter to the height of the container. The average Nusselt number on the bottom hot wall is measured and the effects of the density inversion parameter, the aspect ratio and the Rayleigh number are discussed in detail. Results indicate that there exists different local Nusselt number distributions corresponding to various flow patterns and the average Nusselt number decreases with the increase of the density inversion parameter. The negative effect of the density inversion parameter on heat transfer becomes more significant at high Rayleigh number values. The increasing aspect ratio can enhance the heat transfer of the Rayleigh–Bénard convection. However, the enhancement effect decreases gradually with the increase of the aspect ratio. Furthermore, at large aspect ratios, multiple roll flow patterns appear, the number of the rolls increasing with the aspect ratio. Based on the experimental data, an empirical correlation on heat transfer ability is obtained within an acceptable uncertainty.