水力喷射空气旋流器中射流雾化过程模拟及其机理

水力喷射空气旋流器(WSA)是一种新型高效的气液传质反应设备。采用雷诺应力模型和VOF两相流模型较好地模拟了WSA的气相压降特性、液相回流比和射流雾化过程,并讨论分析了雾化过程的机理。模拟和实验研究表明,WSA的气相压降随着进口气速的增加先后出现低压降区、压降突跳区、压降过渡区和高压降区4个特征区域,并给出了不同压降区域之间转折点气速的计算方法。射流在这4个压降区域里,分别表现为稳态射流、变形与袋式破碎、袋式破碎与剪切雾化和剪切雾化与离心分离等流态。射流在压降过渡区与高压降区的转折点左右实现充分雾化并达到最大相间传质面积。研究结果为建立基于WSA压降特性的射流雾化与流场调控方法提供了理论依据。

Numerical simulation and mechanism of jet atomization in water-sparged aerocyclone

Water-sparged aerocyclone (WSA) is a new type of high efficient gas-liquid mass transfer reaction equipment. The gas phase pressure drop characteristics, liquid phase reflux ratio and jet atomization process in the WSA were better simulated using the Reynolds stress model (RSM) and the multiphase flow model of volume of fluid (VOF). The mechanism of jet atomization process in the WSA was also discussed in detail. Both simulation and experiment results illustrated that the gas phase pressure drop of WSA will go through a low pressure drop zone, a pressure drop jump zone, a pressure drop transitional zone and a high pressure drop zone with the increase of gas inlet velocity. The determination method of a turning point between two adjacent pressure drop areas was given. The water jet presents steady jet, deformation and bag-like breakup, bag-like breakup and shear atomization, shear atomization and liquid drop centrifugation, respectively, in the above-mentioned pressure drop areas. The water jet in the WSA was fully atomized and the mass transfer interface between gas and liquid phases was maximized when the gas phase inlet velocity reached the turning point between the pressure drop transitional area and the high pressure drop area. The results could be used as a theoretic basis for establishing a adjusting method for jet atomization and flow field in the WSA.