运用粘弹性流动分析软件 ANSYS POLYFLOW 对基于体积拉伸流动成型的叶片 挤出机中一个叶片单元的流场进行数值模拟，并将速度梯度张量代入纤维取向分布函数， 计算叶片单元中纤维在不同方向的取向概率，分布函数最大值对应的方向为纤维取向方 向，然后使用数学软件 Matlab 对周向不同剖面上的纤维取向分布进行可视化显示，发现: 在叶片单元入口处纤维主要沿轴向(即挤出方向)取向，在远离叶片单元入口处纤维主要 沿与周向和轴向呈一定夹角的方向取向，结合分散指数分布云图发现拉伸流场比剪切流 场更有利于纤维的取向． 文中还通过实验对数值模拟结果进行了验证，实验结果和数值模 拟结果一致．

In the investigation,the flow field of a vane unit in the vane extruder on the basis of a volume-extension- al field is numerically simulated by means of the CFD software ANSYS POLYFLOW,and the orientation probability of the fiber of the vane unit in all directions is calculated by substituting the velocity gradient tensor of the flow field into a fiber orientation distribution function.The direction of the maximum value of the orientation distribution func- tion is considered to be the main orientation of the fiber.Then,Matlab is adopted to visualize the orientation distri- bution of the fiber on different profiles along the circumference.The results show that the orientation of the fiber at the entrance of the vane unit aligns to the axial direction，which is the extrusion direction,and the orientation of the fiber far away from the entrance of the vane unit is mainly along the direction which has a certain angle with the cir- cumferential direction and the axial direction.By comparing the fiber orientation distribution with the dispersion in- dex distribution,it is found that the extensional field is more conducive to the fiber orientation than the shear flow field.Finally,the numerical results are verified by the experimental results,finding that they accord well with each other.