【摘要】 非溶剂致相分离的干喷湿纺法所制中空纤维膜的微结构与凝固浴的流场结构密切相关。常见的凝固浴流动更新类似于圆形自由射流。该流场结构不仅影响溶液纺丝的稳定性，还影响其分相成膜时的双扩散行为。合适的湍流模型能提高计算的准确性与可靠性，因此采用9种湍流模型来模拟圆形自由射流流动，得到了不同模型下的流体速度分布、起始段长度、湍流动能(k)、卷吸量等参量结果，并与实验值及理论解进行对比分析。结果表明，在k与湍流动能耗散率(ε)中增加了两个附加项(D,E)的Launder与Sharma (LS)模型，对速度分布的预测最准确，轴向无量纲速度平均误差为7.14%，起始段长度与实验值相比平均误差最小为10.7%;Prandtl数σ_k对水流扩散有较大影响，通过修正σ_k，能提高LS模型的速度分布预测能力，当σ_k取0.15时，起始段与主体段的平均相对误差降至2.75%，雷诺数为6378.2条件下的卷吸量预测平均误差为3.57%。因此，在具有圆形自由射流的凝固浴槽数值模拟中，建议采用LS模型。更多还原

【Abstract】 The microstructure of the hollow fiber membrane prepared by the dry jet wet spinning method based on non-solvent phase separation is closely related to the flow field structure of the solidification bath. A common solidification bath flow renewal is similar to a circular free jet. The flow field structure not only affects the stability of solution spinning,but also affects its double diffusion behavior during the membrane phase separation formation. An appropriate turbulence model can improve the accuracy and reliability of the calculation. Nine turbulence models were used to numerically simulate the circular free jet flow. The parametric results such as fluid velocity distribution,initial section length,turbulent kinetic energy(k),and entrainment under different models were obtained,and compared with the experimental values and theoretical solutions. The results show that the Launder and Sharma(LS) model,which adds additional items(D,E) to k and turbulent kinetic energy dissipation rate(ε),has the most accurate prediction of the velocity distribution. The average error of axial dimensionless velocity is 7.14%. The average error of the starting segment length is the smallest compared with the experimental value,which is 10.7%. The Prandtl number σ_k has a great influence on water flow diffusion. The prediction ability of the velocity distribution of the LS model can be improved by regulating the correction coefficient σ_k,and the average relative error is the smallest(2.75%) when σ_k is 0.15. The average error of the prediction of the turbulence entrainment volume under the condition of Reynolds number=6 378.2 is 3.57%. In numerical simulation of solidification bath with circular free jet,LS model is recommended.更多还原