Faroughi Salah A, Del Giudice Francesco
Geo-Intelligence Laboratory, Ingram School of Engineering, Texas State University, San Marcos, TX 78666, USA.
Department of Chemical Engineering, Faculty of Science and Engineering, School of Engineering and Applied Sciences, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EN, UK.
Polymers (Basel). 2022 Feb 9;14(4):657. doi: 10.3390/polym14040657.
The efficient transport of solid particles using polymeric fluids is an important step in many industrial operations. Different viscoelastic fluids have been designed for this purpose, however, the effects of elasticity have not been fully integrated in examining the particle-carrying capacity of the fluids. In this work, two elastic fluid formulations were employed to experimentally clarify the effect of elasticity on the particle drag coefficient as a proxy model for measuring carrying capacity. Fluids were designed to have a constant shear viscosity within a specific range of shear rates, γ˙<50(1/s), while possessing distinct (longest) relaxation times to investigate the influence of elasticity. It is shown that for dilute polymeric solutions, microfluidic rheometry must be practiced to obtain a reliable relaxation time (as one of the measures of viscoelasticity), which is on the order of milliseconds. A calibrated experimental setup, furnished with two advanced particle velocity measurement techniques and spheres with different characteristics, was used to quantify the effect of elasticity on the drag coefficient. These experiments led to a unique dataset in moderate levels of Weissenberg numbers, 0<Wi<8.5. The data showed that there is a subtle reduction in the drag coefficient at low levels of elasticity (Wi<1), and a considerable enhancement at high levels of elasticity (Wi>1). The experimental results were then compared with direct numerical simulation predictions yielding R2=0.982. These evaluations endorse the numerically quantified behaviors for the drag coefficient to be used to compare the particle-carrying capacity of different polymeric fluids under different flow conditions.
使用聚合物流体高效输送固体颗粒是许多工业操作中的重要步骤。为此已设计了不同的粘弹性流体，然而，在研究流体的颗粒承载能力时，弹性的影响尚未得到充分整合。在这项工作中，采用了两种弹性流体配方，通过实验来阐明弹性对颗粒阻力系数的影响，以此作为衡量承载能力的替代模型。设计的流体在特定剪切速率范围γ˙<50(1/s)内具有恒定的剪切粘度，同时具有不同的（最长）松弛时间，以研究弹性的影响。结果表明，对于稀聚合物溶液，必须采用微流体流变学方法来获得可靠的松弛时间（作为粘弹性的一种度量），其量级为毫秒。使用配备了两种先进颗粒速度测量技术和具有不同特性球体的校准实验装置，来量化弹性对阻力系数的影响。这些实验在中等魏森贝格数水平0<Wi<8.5下产生了一个独特的数据集。数据表明，在低弹性水平（Wi<1）时阻力系数有细微降低，而在高弹性水平（Wi>1）时有显著提高。然后将实验结果与直接数值模拟预测进行比较，得到R2 = 0.982。这些评估认可了通过数值量化的阻力系数行为，可用于比较不同聚合物流体在不同流动条件下的颗粒承载能力。
