Abstract To investigate the variation regularity of the characteristic droplet diameters in the swirling flow field, experimental research and numerical simulations were conducted. In the experiments, the white oil–water and the hydraulic oil–water mixture in a 100-mm-diameter pipe swirling flow field were tested. A Malvern droplet size analyzer and an electrical resistance tomography were used to measure the droplet size distribution and local oil volume fraction, respectively. In the numerical simulations, the Eulerian multiphase model, the population balance model, and the RSM turbulent model were coupled to simulate the droplet behavior in the swirling fluid field. The results revealed bilinear relationship (corresponding to the developing section and swirling section) between the section average d32 and the turbulent energy dissipation rate in the logarithmic coordinate system. Subsequently, quadratic relationship between the section average d90 and the swirling number owing to the dual influence mechanism of the tangential momentum on droplet coalescence and stabilization was found. Finally, linear relationship was observed between the d5 and the swirling number in the swirling section. Furthermore, the results indicated that these characteristic droplet diameters were sensitive to the operating parameters of the entrance Reynolds number and entrance oil volume fraction, as well as the oil properties, including the density, viscosity, and surface tension coefficient. All these factors are important for understanding the droplet evolution in the swirling flow field and can provide guidance for the design and optimization of swirling vane type de-oiling separators.

中文翻译：

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旋流流场特征液滴直径变化规律研究

摘要 为了研究旋流流场中特征液滴直径的变化规律，进行了实验研究和数值模拟。实验中，在直径为 100 mm 的管道涡流流场中对白油水和液压油水混合物进行了测试。Malvern 液滴尺寸分析仪和电阻层析成像分别用于测量液滴尺寸分布和局部油体积分数。在数值模拟中，欧拉多相模型、种群平衡模型和RSM湍流模型相结合，模拟了旋流流体场中的液滴行为。结果表明，截面平均d32与湍流能量耗散率在对数坐标系中呈双线性关系（对应于展开截面和旋流截面）。随后，由于切向动量对液滴聚结和稳定的双重影响机制，发现了截面平均 d90 与旋流数之间的二次关系。最后，在旋流段中观察到 d5 与旋流数之间的线性关系。此外，结果表明，这些特征液滴直径对入口雷诺数和入口油体积分数的操作参数以及油的特性（包括密度、粘度和表面张力系数）敏感。