The effect of slip in the flow of a branched PP melt: experiments and simulations
The effect of slip in the flow of a branched PP melt: experiments and simulations
复制标题
支化聚丙烯熔体流动中滑移的影响：实验和模拟
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
S. Hatzikiriakos
中科院分区：
文献类型：
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作者：
E. Mitsoulis;I. B. Kazatchkov;S. Hatzikiriakos
在本文中，支化聚丙烯熔体在10：1轴对称收缩中的可视化和直接速度分布测量实验证明了壁面滑移的开始。流动的视频处理显示了涡旋的形成和随着流量的增加而减弱。采用多模K-BKZ粘弹性模型和纯粘性(Cross)模型进行数值模拟，这两种模型都包含了非线性滑移定律，用来预测流动的运动学和动力学，并通过对速度分布的拟合来推导滑移速度函数。结果表明，数值计算结果与实验结果吻合较好，能较好地反映旋涡的形成、发展和减弱过程。这些实验(入口流动的可视化和直接的速度分布测量)可用于评估聚合物熔体在加工设备中流动的本构方程和滑移定律的有效性。
In this paper visualisation and direct velocity profile measurement experiments for a branched polypropylene melt in a 10:1 axisymmetric contraction demonstrate the onset of wall slip. Video processing of the flow shows the formation of vortices and their diminution with increasing flow rate. Numerical simulations using a multimode K-BKZ viscoelastic and a purely viscous (Cross) model—both of them incorporating a nonlinear slip law—were used to predict the flow kinematics and dynamics as well as to deduce the slip velocity function by performing fitting to the velocity profiles. It was found that the numerical predictions agree well with the experimental results for the velocity profiles, and vortex formation, growth and reduction. It is suggested that such experiments (visualisation of entrance flow and direct velocity profile measurement) can be useful in evaluating the validity of constitutive equations and slip laws in the flow of polymer melts through processing equipment.