论文总字数：39320字

摘 要

当前，碳纤维材料被广泛应用在日常生活和生产中，如何高效且合格地生产碳纤维是企业发展所必须面对的重要问题。聚丙烯腈（PAN）原丝是制备PAN基碳纤维的核心，某石化企业将圆形喷丝头改为矩形喷丝头以适应矩形截面PAN原丝的生产，但在生产中出现毛丝、断丝和白芯等现象，对企业生产造成一系列问题。学者们对圆形分布板做了大量研究，但是对矩形分布板的研究基本为空白，给矩形喷丝头的设计带来了很大的难度。论文主要研究内容如下：

（1）以原厂矩形截面喷丝头为对象，说明其结构组成以及数值模拟中几何模型建立及网格处理方法。在综述流场均匀性各种评价方法的基础上，选择流速相对标准偏差（CV）值作为衡量喷丝头内流场分布均匀度的主要评价指标。

（2）采用数值模拟方法，对圆形喷丝头和原厂矩形喷丝头内流场进行计算。依据喷丝头内流场的压力与速度分布以及喷丝板前沿径向各截线上的轴向流速分析，探讨造成原厂矩形喷丝头出丝断裂、丝束缠结的主要原因。以圆形喷丝头的流场分布规律及速度分布均匀度为评价基准，指出矩形分配板结构改进的方向。

（3）以喷丝板前轴向流速分布的CV值为评判依据，分析矩形分配板导流锥对喷丝头内流场均匀度的影响。结合喷丝板未开孔区外缘的轴向流速分布状态，探讨导流锥底角角度及平截锥面直径的取值范围。

（4）考察导流锥锥体开孔结构对喷丝头内流动状态的影响。依据喷丝板前轴向流速的的分布曲线和CV值，探讨导流锥锥体上的开孔圈层数、圈距和圈孔数对流场均匀度的影响。

（5）采用正交实验法对导流锥进行优化，优化后导流锥底角15°，平截圆锥直径20mm，导流锥上三圈层开孔，圈距7.5mm，第二圈开孔数为16。物料轴向速度峰值降至12mm/s，喷丝板前截面整体CV值减小为47.61%。模拟结果表明优化后分布板的流场均匀性有了较大改善，能够满足生产需要。

关键词：矩形分布板 导流锥 数值模拟 丙烯腈 相对标准偏差

ABSTRACT

At present, carbon fiber materials are widely used in daily life and production. How to efficiently and qualifiedly produce carbon fiber is an important issue that must be faced by enterprise development. Polyacrylonitrile (PAN) raw silk is the core of the preparation of PAN-based carbon fiber. A petrochemical company changed the round spinneret to a rectangular spinneret to adapt to the production of rectangular cross-section PAN raw yarn, but wool and breakage occurred in the production. Phenomena such as silk and white core have caused a series of problems for the production of enterprises. Scholars have done a lot of research on the circular distribution plate, but the research on the rectangular distribution plate is basically blank, which brings great difficulty to the design of the rectangular spinneret. The main research contents of the paper are as follows:

(1) The structure of the spinning jet with a rectangular section, the geometric model building, and grid treatment were introduced. The relative standard deviation (RSD) value of flow velocity was taken as the main indicator in the evaluation of flow field distribution uniformity inside the spinning jet based on the review of various evaluation methods of flow field uniformity.

(2) The internal flow fields of the circular spinning jet and the rectangular spinning jet in use were calculated using the numerical simulation method. The pressure and velocity distribution of the flow field inside the spinning jet as well as the axial velocity of the radial sections in front of the spinneret plate were analyzed to probe into the main causes of broken and tangled fiber of the spinning jet. The improvements of the rectangular distribution structure were put forward based on the distribution law of flow field and the uniformity of velocity distribution of the circular spinneret spinning jet.

(3) The effect of the opening structure in the middle of the rectangular distribution plate on the flow state inside the spinning jet was investigated. Specifically, the influence of the number of layers with openings, the distance between two circles and the number of openings in the middle of the rectangular distribution plate on the flow field uniformity was explored according to the distribution curve and RSD value of the axial velocity in front of the spinneret plate.

(4) The impact of the rectangular distribution plate guide cone on the uniformity of the flow field inside the spinning jet was analyzed based on the RSD value of the axial velocity distribution in front of the spinneret plate. The bottom angle of the guide cone and the diameter range of the plane section of the cone were analyzed combining with the axial velocity distribution at the outer edge of the unopened area of the spinneret plate.

(5) Orthogonal experimental method is used to optimize the diversion cone. After optimization, the diversion cone has a base angle of 15 °, a truncated cone diameter of 20mm, and three layers of holes in the diversion cone. The number of holes is 16. The peak value of the material axial velocity is reduced to 12mm / s, and the overall CV value of the front section of the spinneret is reduced to 47.61%. The simulation results show that the optimized flow field uniformity of the distribution plate has been greatly improved and can meet the production needs.

KEYWORDS: Rectangular distribution plate；Diversion cone；Numerical simulation；Acrylonitrile；Relative standard deviatio

目 录

摘 要 I

ABSTRACT i

第一章 绪 论 1

1.1 课题研究背景及意义 1

1.1.1 研究背景 1

1.1.2 研究意义 3

1.2 碳纤维材料的研究及发展趋势 5

1.2.1 国外碳纤维发展历程 5

1.2.2 国内碳纤维发展历程 5

1.2.3 碳纤维的发展趋势 6

1.3 研究内容 6

1.4 研究方法 7

第二章 数值模拟方法 9

2.1 喷丝头模型构建 9

2.1.1 SolidWorks三维建模软件简介 9

2.1.2 几何模型 9

2.2 ICEM网格划分 11

2.3 控制方程 13

2.3.1 质量守恒方程 13

2.3.2 动量守恒方程 14

2.3.3 能量守恒方程 14

2.4 流动模型 14

2.4.1 层流模型 14

2.4.2 多孔介质阶跃模型 15

2.5 边界条件 15

第三章 喷丝头内流场分析方法 17

3.1 流场均匀性评价方法 17

3.1.1 相对标准偏差法 17

3.1.2 均匀性指数法 17

3.1.3 基于质量及面积加权平均速度的 18

3.1.4 速度/压力云图法 18

3.2 流场分布规律评价方法 19

3.2.1 圆形喷丝头流场分布规律评价方法 19

3.2.2 矩形喷丝头流场分布规律评价方法 20

第四章 不同喷丝头内流场的分析 21

4.1 圆形喷丝头内流场数值模拟结果分析 21

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