Abstract: The fluid dynamics characteristics of bubbly jet in gas-liquid two-phase flow affect the mass transfer, heat transfer, and momentum exchange between gas-liquid phases, which is crucial for enhancing the mixing between gas-liquid phases. In order to explore the flow characteristics of gas-liquid two-phase flow in power-law fluids, the hydrodynamic characteristics of bubbly jet was studied by the numerical simulation method. The effects of different flow rate ratios and liquid rheological properties on gas phase velocity, bubble size, gas holdup distribution, and gas-liquid two-phase flow patterns were analyzed in water and sodium carboxymethyl cellulose (CMC) aqueous solutions with different concentrations. The results showed that due to the diffusion movement of the gas phase and the disturbance to the liquid phase environment, the vortex structure existed in the flow field, and the interaction between the gas and liquid phases was enhanced. With the increase of the flow rate ratio, the turbulence in the flow field was strong, the gas-liquid two-phase mixing was promoted, the streamline was diffused, and the distribution was scattered. The diameter of the bubble increased, and the size distribution of the bubble gradually changed from single peak to double peak with the increase of the flow rate ratio, and the distribution range of bubble diameter increased with the increase of the liquid phase concentration. Compared to tap water, the gas holdup of the bubbly jet in CMC aqueous solution was small, the bubble dispersion width increased, and the flow behavior of the bubbly jet changed. With the increase of the flow rate ratio, the turbulence in the flow field was enhanced, the volume fraction of the gas phase at the core of the bubble jet increased, the local mixing was strengthened by the vortex structure. The width of dispersion from the gas phase to the liquid phase increased, the effective contact area of the gas-liquid interface increased, and the mass transfer efficiency between the gas-liquid phases increased. The dispersion effect was obvious with the increase of the liquid phase concentration.

Key words: bubbly jet, power-law fluids, numerical simulation, gas-liquid two-phase flow

摘要： 在气液两相流中气泡射流的流体动力学特性影响气液两相间的传质传热及动量交换，对于强化气液两相间的混合至关重要。为探究幂律流体中气泡射流流动特性，采用数值模拟方法对气泡射流的动力学及水力学特性进行研究。考察了清水和不同浓度羧甲基纤维素钠(CMC)水溶液中，气液比和液相流变特性对气相速度、气泡尺寸、气含率分布及气液两相流态的影响。研究表明，由于气相的扩散运动以及对液相环境的扰动，流场内存在涡旋结构，增强了气液两相间相互作用。随气液比增大，流场内湍动剧烈，促进气液两相混合，扩散了流线，流线分布疏散。气泡直径增大，气泡尺寸分布由单峰逐渐向双峰转变，且随液相浓度增加气泡直径分布范围增大。相较于清水，CMC水溶液中气泡射流气含率低，气泡分散宽度增加，气泡射流的流动行为发生变化。随气液比增加，流场内湍动加强，气泡射流核心处气相体积分数增加，涡结构强化了局部混合。气相向液相环境中的分散宽度增加，气液界面的有效接触面积增加，气液两相间的传质效率提高，且随液相浓度增加分散效果更明显。

关键词: 气泡射流, 幂律流体, 数值模拟, 气液两相流