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The simulation results of the cylinder-block model were given in the article, consistent with that of Middlemen"s. It was shown that the block part could improve the uniformity of the flow distribution. The analysis of the flow field of some materials with different power-law factor in the die designed by Mckelvey was close to that of Mckelvey"s. It was shown that the flow distribution was uniform in the die that can producesheets with 1200mm in width. During the analysis the flow channel was divided into several parts to get the details about the fluid flow in each area. A conclusion was drawn after analyzing the influence of the die pressure on the flow distribution, that the higher pressure is good for the output and bad for the uniformity of the distribution. Simulation of the die applying the cylindrical main runner showed the fact that when the cylinder replaced the cone the change of uniformity was trivial. The uniformity of the non-block flow channel was so poor that the block in the proper position of the die channel was necessary. The project of the die for the wider sheet was put forth, and the analysis of the fluid flow in the die was shown.

本文模拟了圆柱管缝隙流模型的三维流动场，得到了与Middlemen结论一致的流动均匀性，并通过模拟直观地展示了采用阻尼块可以改善挤出均匀性的现象；分析了多种幂率指数的流体在Mckelvey等人设计的流道模型中的流动分布，得到了与Mckelvey的分析结果接近的压力降和流量偏差；本文建立了1200mm幅宽机头流道的三维有限元模型，并逐个分析各个区域和多个截面的流动分布状况，由此揭示了1200mm幅宽L-型机头流道内的流北京化工大学硕士学位论文动分布基本均匀，并在分析了机头压力对于挤出流动分布的影响后得出结论：较高的机头压力可以获得较大的产量，但是不利于物料均匀分布；模拟了采用圆柱管主流道时机头流道内的流动分布，得出结论：主流道由圆锥管改为圆柱管时对流动均匀性影响不大，通过设置适当的阻尼仍然可以达到挤出平衡；模拟了两端进料式圆柱管无阻尼流道的流动均匀性后得到结论：两端进料式无阻尼结构的流动均匀性较差，宽机头中仍然有必要设置阻尼块；确定宽幅机头流道的基本方案，并设计了一种宽幅防水卷材挤出机头流道的结构，通过流动模拟表明该种结构的流动均匀性较好；考察了宽幅机头对于不同厚度片材的挤出适应性，得到结论：当生产不同厚度的片材时，阻尼块高度需要调整。

In this dissertation the"Penalty"finite element method was employed to compute the velocity of the three-dimensional flow of power-law fluid in a profile die. In order to decrease the needed computer memory and raise the stability of numerical simulation, a set of decoupled methods such as PFEM, pseudo-body force method and transformation of momentum equation to the elliptic equation was developed to establish the general finite element equations to compute the distributions of velocity and viscoelastic stress of the three-dimensional viscoelastic flow of the Phan ThienTanner fluid in a profile die. During numerical simulation of the extrudate swell of the PTT fluid, the flow in the die and out of the die was analyzed separately, which demands less computer memory. The key techniques used in numerical simulation of the three-dimensional extrusion from dies such as decision of boundary conditions, creation of initial velocity field, selection of penalty factor, high Weissenberg number problem , regeneration of the free surface were studied in detail.

中文题名聚合物异型材口模挤出三维流动研究副题名外文题名 Study on three-dimensional flow of polymer melts during the process of profile extrusion from dies 论文作者涂志刚导师柳和生包忠诩教授学科专业材料加工工程研究领域\研究方向学位级别博士学位授予单位南昌大学学位授予日期2001 论文页码总数148页关键词挤出成型聚合物材料挤出口模聚合物异型材馆藏号BSLW /2003 /TQ320 /9 本文建立了求解挤出口模内幂律流体流动速度场的通用三维罚有限元模型；对于非线性粘弹性的Phan Thien-Tanner流体，为了降低模拟计算对计算机硬件的要求，并使模拟计算更加稳定，采用了一种去耦算法，包括罚有限元方法、拟体力方法和动量方程的椭圆类方程转化方法，并建立了求解速度场和粘弹性应力场的总体有限元方程；对于PTT流体的挤出胀大问题，提出了挤出胀大熔体口模内外分离模拟法，这样可以显著降低数值模拟对计算机硬件的要求。

In addition, the important forms used to calculate the formation parameter s, such as shale volume, water saturation and permeability, are improved to be more suitable for the calculation of inhomogeneous formation parameter s according to the power law of fract.

同时，利用分形理论的幂定律，对泥质含量、含水饱和度和渗透率等参数的计算公式作了改进，可以更好地适应非均质地层参数的计算。

The average heat transfer and friction factor results from experiments can be well correlated by power law equation.

实验得到的通道平均Nu数及通道阻力系数均可用Re数的幂函数来表示。

Taking power law fluid as an example, a method of solving the non-Newtonian lubrication in journal bearing is introduced.

以幂率流体为例，介绍了一种求解径向轴承非Newton润滑的方法。

The influences of volumetric coefficient, pressure coefficient, temperature coefficient, and leakage coefficient on compressor volumetric efficiency were analyzed.

容积系数主要与压缩机的结构尺寸和吸、排气压力比有关，压力比的变化对容积系数构成以多变膨胀指数为幂的指数影响；转速变化对压力系数构成二次影响；温度系数和泄漏系数同时受到与压力比和转速的影响。

Applying the laws, the high-effectively transporting of viscous fluid can easily realizedIt is provided and consulted conveniently in the oik chemistry, circumstance , mill-run and convective thermodynamics to successfully calculate, especially on Bingham fluid, Non-Newton fluid.

对非牛顿流体中幂律流体和宾汉流体的成功数值计算，尤其是对具有流核的宾汉流体的较成功数值计算，为石油、化工、环境工程、选矿和对流传热学等方面的应用提供了方便和参考。

During the prior fatigue life, fatigue damage induces a very small stiffness reduction value that always may be neglected. In the final fatigue life, the stiffness reduction evidently minishes following the power function.

在疲劳寿命前期，疲劳损伤对复合材料层板产生的刚度降变化很小，可忽略不计；在疲劳寿命后期，刚度降则按幂函数变化显著减小。

The effect of solidgrain diffusion was reflected by f0. The core diffusion could be excluded by minishing theparticle scales, but the solid grain diffusion could not.

在常见幂函数形式的速率方程中引入修正系数f0体现了固体扩散对反应的影响，说明减小催化剂粒径，只能排除孔扩散的影响，并不能排除固体扩散对反应的影响。

Experiments were carried out under greenhouse condi- tions to measure the growth rate of mycelia and uredia in leaf tissues.

结果表明，接种后48小时到192小时，菌丝体在叶片组织内扩展长度与时间里幂函数回归关系，慢锈品种是Y=0.0879X~(1.3459)；快锈品种是Y=0.1205X~(1.3859)。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。