Foam flow phenomena in sudden expansions and contractions
Foam flow phenomena in sudden expansions and contractions
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DOI：
10.1016/s0301-9322(01)00017-9
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发表时间：
2001-08-01
影响因子：
3.8
通讯作者：
Barigou, M
中科院分区：
文献类型：
--
作者：
Deshpande, NS;Barigou, M
面积的突然变化会引起泡沫中复杂的瞬态过程，随着流速的增加，这种过程的重要性也会增加。这些效果是泡沫产生方法的函数，因此取决于初始泡沫结构。在突然膨胀或收缩时的垂直向上流动中，泡沫中的大部分液体流回上游。这导致下游的持液量大大减少，并且上游的再循环流态。对于所研究的配件的面积比，在突然收缩的情况下持液率降低的程度不太明显。在低气体速率下，接头两侧通常存在活塞流状态；然而，随着气体吞吐量的增加，配件的存在导致上游再循环流态的建立。在足够高的流速下，泡沫结构发生完全破坏，导致下游“溢流”状态的开始。通过双参数幂律模型成功地描述了泡沫流变学，并且可以通过简单的显式关系来描述泡沫流动的摩擦系数。 (C) 2001 Elsevier Science Ltd. 保留所有权利。
A sudden change in how area induces complex transient processes in foams, which increase in significance with increasing flowrate. The effects are a function of the method of foam generation and, hence, depend on the initial foam structure. In vertical upflow at a sudden expansion or contraction, a substantial fraction of the liquid in the foam drains back upstream. This leads to a greatly reduced liquid holdup downstream and a recirculating flow regime upstream. For the area ratios of the fittings investigated, the extent of liquid holdup reduction was less pronounced in the case of a sudden contraction. At low gas rates, a plug flow regime usually existed on either side of the fitting; however, with an increase in gas throughput the presence of the fitting led to the establishment of a recirculating flow regime upstream. At sufficiently high flowrates complete breakdown of foam structure occurred resulting in the onset of a 'flooding' regime downstream. Foam rheology was successfully described by a two-parameter power-law model, and the friction factor for foam flow could be described by a simple explicit relationship. (C) 2001 Elsevier Science Ltd. All rights reserved.