碳纤维出丝槽流系统结构尺寸优化

Structure and size optimization of groove flow system for carbon fiber

为减小碳纤维原丝生产工艺中双扩散过程对原液细流进入浴槽凝固成初生纤维的影响,必须保证出丝槽流系统中流场的稳定性.采用时变雷诺方程和标准k-ε湍流模型,模拟计算不同形状和结构尺寸的喷丝孔外罩对碳纤维出丝槽流系统流域中湍流的影响.利用不同长高比二维矩形钝体模型计算高雷诺数下绕流的情形,对比不同尺寸下尾流内湍流的大小,分析得到较优的结构参数.结果表明,外罩长高比是影响湍流大小的主要因素;长高比增大有利于减弱尾流内的湍流;当长高比接近4时,喷丝口处湍流较小,但长高比再增大,湍流减小程度不明显.

During the production process of carbon precursor fiber, the stability of flow field in groove flow system should be ensured to reduce the influence of double diffusion process when the spinning dope solidifies into as-spun fiber after flowing into the groove. The influence of spinneret covers with different shapes and dimensions on turbulent flow in the fiber groove flow system is simulated using the unsteady Reynolds equations and standard k-s turbulence model. The detour flow is calculated by 2D rectangular bluff body models with different length-height ratios under high Reynolds number. The optimum structural parameters are obtained after comparing the magnitude of turbulences in the wake flow. The results show that, the length-height ratio of the cover is the main influencing factor on turbulence magnitude ; when the ratio is close to 4, the turbulent flow near spinneret is relatively small, but after that the turbulence reduction is not obvious as the ratio increases.