In this paper, the formation mechanism of droplets of shear-thinning non-Newtonian fluids in a step-emulsification microdevice is studied experimentally, by using aqueous solutions of sodium carboxymethyl cellulose (CMC) as the dispersed phase and cyclohexane as the continuous phase. According to the evolution of the front-end length of the dispersed thread over time, the droplet generation process is divided into three stages: the two-dimensional expansion stage, the three-dimensional rapid expansion stage, and the necking stage. The influence of the dispersed phase flow rate Q_d and CMC concentration c on droplet formation is described. The results show that the addition of CMC in the aqueous solution increases the viscosity of the dispersed phase and slows down the evolution of the dispersed phase, thereby resulting in the increase of the droplet size. Finally, a droplet volume prediction model considering non-Newtonian characteristics is proposed, and the formation of satellite droplets is analyzed.

中文翻译：

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在逐步乳化微装置中形成剪切稀化的非牛顿流体液滴

本文以羧甲基纤维素钠（CMC）水溶液为分散相，环己烷为连续相，实验研究了剪切稀化非牛顿流体液滴在步进乳化微装置中的形成机理。根据分散线前端长度随时间的演变，液滴生成过程分为三个阶段：二维膨胀阶段、三维快速膨胀阶段和颈缩阶段。分散相流速Q _d和 CMC 浓度c 的影响对液滴形成进行了描述。结果表明，CMC在水溶液中的加入增加了分散相的粘度，减缓了分散相的演化，从而导致液滴尺寸增加。最后，提出了一种考虑非牛顿特性的液滴体积预测模型，并分析了卫星液滴的形成。