Flow behaviour of drop and jet modes of a laminar falling film on horizontal tubes
Flow behaviour of drop and jet modes of a laminar falling film on horizontal tubes
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水平管上层流降膜的滴流和喷射模式的流动行为
DOI：
10.1016/j.ijheatmasstransfer.2018.03.111
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发表时间：
2018-09
影响因子：
5.2
通讯作者：
Pourkashanian Mohamed
中科院分区：
文献类型：
--
作者：
Ding Hongbing;Xie Peng;Ingham Derek;Ma Lin;Pourkashanian Mohamed
水平管降膜流动特性对水平管蒸发器和吸收器的传热传质效率有重要影响。因此，它是至关重要的，以调查的接触角和比流量的液膜和液滴的流体动力学的液滴和射流模式，这是最重要的模式蒸发器和吸收器的效果。采用流体体积（VOF）方法建立了三维CFD模型，以捕捉气液界面。通过网格细化和独立性检验，对完全润湿条件下的液膜铺展和液滴形成、液桥断裂、液滴脱离、冲击波和波动波进行了模拟，模拟结果与实验数据和理论吻合较好。在液滴模式下，观察到液滴从相邻位置交替下落的行为，包括不稳定的细长液桥和复杂的鞍波。这表明，波的传播速度首先高于冲击速度。在直列射流模式下，流态几乎是稳定的，但它受到冲击波的微弱扰动。由于波的相互作用，环向气膜的最大厚度位于两柱同轴射流的中部。此外，随着接触角的增大，降膜的润湿面积、铺展速度和失稳时间均减小，而在较高的比流量下，前两个参数均增大。特别地，在较大的接触角下发生过冲。结果表明，降膜流流型对初始润湿条件敏感。此外，它揭示了最终的稳定润湿区域取决于后退接触角，因此动态接触角的引入是准确确定降膜行为的最佳方法。
The flow behaviour of a falling film on horizontal tubes has significant impacts on the efficiency of heat and mass transfer for the horizontal tubular evaporators and absorbers. Thus it is crucial to investigate the effect of contact angle and specific flow rate on the hydrodynamics of films and droplets in the drop and jet modes, which are the most important modes for evaporators and absorbers. A three-dimensional CFD model, using the volume of fluid (VOF) method, has been built to capture the gas-liquid interface. By employing mesh refinement and independence tests, the film spreading and droplet formation, liquid bridge breakup, droplet detachment, impact and fluctuation waviness of the simulations at the completely wetting condition are found to be in good agreement with experimental data and theory. In the drop mode, the behaviours of the droplets alternately falling from neighboring sites, including unstable slender liquid bridge and complex saddle waves were observed. This indicates that the wave propagation speed at first is higher than the impaction speed. In the in-line jet mode, the flow pattern is almost stationary but it is perturbed weakly by the impaction wave. The circumferential ring film has its maximum thickness located at the middle of the two-column in-line jet due to the wave interaction. In addition, the wetting area, spreading speed and instability time of the falling film are reduced with an increase in the contact angle, while the first two parameters increase at higher specific flow rates. In particular, an overshoot occurred at the larger contact angle. Finally, the results showed that the falling film flow pattern is sensitive to the initial wetting condition. Further, it reveals that the final steady wetted region depends on the receding contact angle, thus the introduction of the dynamic contact angle is the best approach for accurately determining the behaviour of falling films.
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影响因子：
6.4
作者：
Y. Lazcano-Véliz;J. Hernández;D. Juárez-Romero;A. Huicochea-Rodríguez;A. Alvarez‐Gallegos;J. Siqueiros
通讯作者：
Y. Lazcano-Véliz;J. Hernández;D. Juárez-Romero;A. Huicochea-Rodríguez;A. Alvarez‐Gallegos;J. Siqueiros
水平管外流动行为和薄膜分布的 3D 模拟
DOI：
10.1016/j.ijheatmasstransfer.2016.11.009
发表时间：
2017-04
影响因子：
5.2
作者：
Qiu Qinggang;Meng Chuiju;Quan Shenglin;Wang Weishu
通讯作者：
Wang Weishu
影响因子：
6.4
作者：
M. Fiorentino;G. Starace
通讯作者：
M. Fiorentino;G. Starace
影响因子：
--
作者：
J. Lienhard;P. Y. A. Wong
通讯作者：
J. Lienhard;P. Y. A. Wong
影响因子：
9.9
作者：
Li Xua;Shichang Wang;Yuxin Wang;Yi Ling
通讯作者：
Li Xua;Shichang Wang;Yuxin Wang;Yi Ling