A novel multiscale theoretical model for droplet coalescence induced by turbulence in the framework of entire energy spectrum
A novel multiscale theoretical model for droplet coalescence induced by turbulence in the framework of entire energy spectrum
复制标题
全能谱框架内湍流引起的液滴聚结的新型多尺度理论模型
DOI：
10.1016/j.ces.2017.10.045
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发表时间：
2017
影响因子：
4.7
通讯作者：
He'an Luo
中科院分区：
文献类型：
--
作者：
Shenggao Gong;Luchang Han;He'an Luo
本文主要研究湍流引起的液滴聚结现象。提出了湍流涡旋与液滴的两种相互作用机制，并通过计算可直接导致聚并的碰撞次数，提出了每种机制对应的聚并模型。以往的聚结模型大多只考虑与液滴大小相等的湍流涡流的贡献，因为液滴的速度被假设为与相同大小的湍流涡流的速度相等。相比之下，该模型考虑了多尺度湍流涡流（即不同尺寸的湍流涡流，而不仅仅是尺寸与液滴大小相等的湍流涡流）对给定尺寸液滴聚并的贡献。本工作还模拟了整个能谱框架内的聚并。同时考虑了液滴与涡流的平均无碰撞路径以及涡流的寿命对聚并的影响。此外，本文还提出了一种新的二阶纵向结构函数，其结果与直接数值模拟结果吻合较好。最后，该模型预测的液滴尺寸分布与实验数据吻合较好。
This work mainly focused on the droplet coalescence induced by turbulence. Two kinds of interaction mechanisms between turbulent eddies and droplets were proposed, and the corresponding coalescence model for each mechanism has also been proposed by counting the number of collisions that can lead to coalescence directly. Most of previous coalescence models only considered the contribution of the turbulent eddies of size equal to the size of droplets since the droplet velocity was assumed to be equal to the velocity of turbulent eddies of same size. In contrast, the contribution of multiscale turbulent eddies (i.e. turbulent eddies with various sizes, not just the turbulent eddies of size equal to the size of droplets) to the coalescence of droplets of given sizes was considered in the proposed model. This work also simulated the coalescence in the framework of entire energy spectrum. Simultaneously, the influences of the average collision free path between droplets and turbulent eddies as well as the lifetime of turbulent eddies on the coalescence were considered. Furthermore, this work proposed a novel second-order longitudinal structure function, which showed a good agreement with the results of direct numerical simulation. Finally, the predicted droplet size distributions of the proposed model were in agreement with experimental data.