啮合型异向旋转双螺杆C形小室内熔体流动的数值模拟

用阻尼最小二乘法，在假定流场为二维的前提下，对Ｃ形小室内的①牛顿流体的等温流动；②牛顿流体的非等温流动；③非牛顿流体的等温流动和④非牛顿流体的非等温流动进行了数值模拟及结果分析。为今后研究啮合型异向旋转双螺杆的熔体输送特性创造了条件，     

微/小通道内非牛顿流体多相流动与传热研究展望

概述了微/小尺度非牛顿流体多相流动与传热现象。在评述国内外已有文献的基础上,从实验研究与数值模拟二方面介绍了非牛顿流体管内多相流动与传热研究的现状、存在的问题。总结了微小通道内非牛顿流体多相流动与传热研究领域中若干值得探索的研究切入点,提出了若干值得探索的研究内容。讨论了非圆截面微通道试验器件的设计与加工、流动可视化与流型采集、流动参数测量、数值模拟等关键技术解决思路,给出了微/小通道内非牛顿流体的绝热气液二相流动可视化实验、流动沸腾传热及可视化实验设计方案,可为深入探索微/小尺度非牛顿流体管内多相流动与传热特性提供参考和借鉴。     

柴油低温粘温特性和流变性研究

考察了柴油加入低温流动改进剂前后的低温粘温特性和流变特性。结果表明,随着温度降低,柴油的表观粘度和粘流活化能增大,稠度系数增大．流动特性指数减小,柴油的流变特性越来越偏离牛顿流体,非牛顿性越来越强,柴油在低温下为假塑性非牛顿型流体。加入低温流动性改进剂T1804 后,柴油的低温表现粘度和粘流活化能显著降低,柴油的流动特性指数值增大,稠度系数值减小,与未加剂柴油相比,更接近于牛顿流体。     

压缩空气A类泡沫水平管路压降实验及数值模拟

压缩空气A类泡沫是具有非平衡自组织结构的两相可压缩非牛顿流体,针对不同发泡倍数的泡沫特性进行水平管路压降实验及数值模拟研究。泡沫具有良好的压缩性能,其内部压力随着压缩体积的增加呈指数型增长,并在1 MPa的实验压力下可保持结构稳定而不发生泡沫破碎。泡沫属于非牛顿流体,具有剪切变稀的性质,其黏度流变行为符合Herschel-Bulkley模型。综合考虑其压缩性能及黏度变化,运用Fluent数值模拟软件针对不同发泡倍数的泡沫在水平管路中的层流流动进行模拟,并通过实验检验其压降模拟结果的可靠性,结果表明其误差可控制在10%以内,模拟方法具有一定的准确性。     

聚合反应工程——第5章 非牛顿流体的传递过程(一)

5.1 化工流变学基础 5.1.1 非牛顿流体概述 在聚合物生产中,往往要处理聚合物溶液、聚合物熔体或高固物含量浓悬浮液等非牛顿流体,其流动、传热、传质等特性,均与牛顿流体有很大的差别。因此,非牛顿流体的传递过程,是聚合反应工程研究的一个重要领域,而弄清聚合物系的流变行为,即     

微通道内屈服应力型流体的流变特性及多相流研究进展

屈服应力型流体（YSFs）是一种典型的非牛顿流体,因其丰富的流变特性被广泛关注。屈服应力是高浓度的粒子分散系统和凝胶状物质（多相乳液、微胶囊、3D打印复杂结构、药物输送凝胶等）的基本特征。本文对微通道内简单屈服应力型流体的流动特征和流变行为,及其流变性对多相流系统的影响进行了综述,剖析了受限空间内流体流动与流体流变性,及多相流动力学和界面现象的耦合机制,并对亟需推进的研究方向进行了展望。为微通道内屈服应力型流体的数值模拟、实验研究和应用提供参考。     

压缩空气A类泡沫水平管路压降实验及数值模拟

压缩空气A类泡沫是具有非平衡自组织结构的两相可压缩非牛顿流体,针对不同发泡倍数的泡沫特性进行水平管路压降实验及数值模拟研究。泡沫具有良好的压缩性能,其内部压力随着压缩体积的增加呈指数型增长,并在1 MPa的实验压力下可保持结构稳定而不发生泡沫破碎。泡沫属于非牛顿流体,具有剪切变稀的性质,其黏度流变行为符合Herschel-Bulkley模型。综合考虑其压缩性能及黏度变化,运用Fluent数值模拟软件针对不同发泡倍数的泡沫在水平管路中的层流流动进行模拟,并通过实验检验其压降模拟结果的可靠性,结果表明其误差可控制在10%以内,模拟方法具有一定的准确性。     

Numerical simulation of three-dimensional flow field of spiral ribbon-screw impeller

应用计算流体力学数值模拟方法,研究了螺带-螺杆组合式搅拌器对高黏度非牛顿流体的搅拌流场特性。结合实例,考察了宏观流场、速度场、剪切速率和表观黏度的分布,分析了流变指数对搅拌特性的影响,并计算了不同工况下的搅拌功率。结果表明：螺带-螺杆组合搅拌器针对高黏度流体,具有良好的全局搅拌特性,在本文的模拟条件下,组合桨的Metzner常数k_s约为13.8,而流变指数变化对k_s的影响不大,为螺带-螺杆搅拌桨在高黏度非牛顿流体搅拌中的应用提供有益指导和参考。     

非牛顿流体搅拌流场的数值模拟研究进展

对非牛顿流体搅拌流场数值模拟过程中的控制方程、旋转桨叶的处理以及数值计算方法三个方面进行了综合论述。阐述了广义牛顿流体模型形式简单、计算量低,在非牛顿流体搅拌流场数值模拟过程中应用广泛;黏弹性流体本构方程具有高度的非线性,采用计算流体力学(CFD)方法对其搅拌流场进行数值模拟难度较高,目前仍处于起步阶段;通过合理简化黏弹性流体本构方程以及采用恰当的数值离散方法,有助于在黏弹性流体的搅拌流场数值模拟中取得进展。     

静态混合器中非牛顿流体的压力降和摩擦因子

分析和讨论了非牛顿流体流动的流变特性、静态混合器的几何本数和单元数及操作参数对非牛顿流体的压力降和摩擦因子的影响。并得到了静态混合器中非牛顿流体流动的压力降的关联式，△Ｐ＝１８３６Ｒｅ（０．２７１）×ｍ（１．０３）Ｋ（０．８５５）（Ｌ／Ｄ）（０．５５９）。     

流体流变性对错位六弯叶桨流场特性的影响

利用计算流体力学(CFD)的方法,以高黏牛顿流体和假塑性非牛顿流体为研究对象,对错位六弯叶桨在层流域的搅拌流场特性进行了研究。结果表明:数值计算得到的功率值与实验测量值吻合较好,搅拌雷诺数对假塑性流体搅拌流场的量纲一速度和切应变速率影响较大,因此提高转速对改变流场的速度及切应变速率分布是一个有效的办法;而流体的流变性只对假塑性流体的量纲一速度有明显影响,对切应变速率影响较小,当流变指数n<0.3时与n基本无关。当流动由层流向过渡流转变时,搅拌桨的流量准数及泵送效率有显著提高;假塑性流体的流变指数降低时,其泵送效率显著下降。研究进一步认识了错位桨在不同流体中的搅拌流场特点,为高黏假塑性流体搅拌桨的设计、应用以及开发新型搅拌桨提供了参考。     

A Modeling Approach to Reaction of Non-Newtonian Fluids in Tubular Reactor

The treatment of non-Newtonian fluids in tubular reactors is frequently encountered in industries, which may be studied by mathematical modeling. The modeling of endothermic reactions of non-Newtonian fluids in tubular reactors with radial dispersion has been done for Ostwald-de-Waele power law fluids. The coupled mass balance, heat balance and velocity equations have been dealt with. The model is solved using finite difference numerical methods. The effect of variation in the dimensionless parameters of the model has also been studied. In addition, the rheological parameter n also affects the reactor performance as well as the velocity profile. An increase in n leads to higher velocity distortion and a decrease in conversion and temperature.     

Non-Newtonian flow in porous media

In this article we present a review of the single-phase flow of non-Newtonian fluids in porous media. The four main approaches for describing the flow through porous media in general are examined and assessed in this context. These are: continuum models, bundle of tubes models, numerical methods and pore-scale network modeling.     

Improved parametric characterization of flow geometries

An improved parametric method is presented for characterization of the flow geometry in the rectilinear flow of non-Newtonian fluids in open and closed conduits of arbitrary crosssection and in purely viscous, inelastic flow of non-Newtonian fluids through packed beds and porous media. In the new formulation, an infinite number of geometric parameters characterize the flow geometry. The actual number required in a particular application is shown to be determined by the fluid model equation representing the rheological behavior of the fluid. For Ostwald-de-Waele and Ellis fluids with flow behavior indices s = 1/n and α integers, the number of geometric parameters required to represent the relationship between flow rate and pressure drop is given by s + 1 and α + 1, respectively. The efficacy of the present method is demonstrated by comparisons with available results for various fluid models and flow geometries.     

鼓泡反应器中幂律型流体流动与传质特性

很多废水处理装置涉及非牛顿型流体中的多相流动和传质问题,研究其中的气液传质过程有助于实现装置的优化设计和高效节能运行。以鼓泡反应器内清水和不同质量分数的羧甲基纤维素钠（CMC）水溶液为实验对象,分别研究气相表观气速和液相流变特性对气泡尺寸分布、全局气含率和体积氧传质系数的影响。实验结果表明,液相的流变特性对其传质特性参数均有较大影响。与清水相比,CMC水溶液中气泡平均直径和分布范围更大;清水和CMC水溶液的全局气含率均随表观气速的增加而增大;CMC水溶液的体积氧传质系数随CMC水溶液质量分数的增加而减小。基于实验研究,得出修正的体积氧传质系数公式和适用于幂律型非牛顿流体流动体系氧传递过程的无量纲关联式,可很好地实现非牛顿流体流动的废水处理装置中气液传质参数的计算。     

Bubble drag and mass transfer in non-newtonian fluids: Creeping flow with power-law fluids

The drag and mass-transfer characteristics of a gas bubble moving in power-law non-Newtonian fluids are examined analytically in terms of the rheological properties of the system. An approximate solution for the case of creeping flow around circulating bubbles shows that the mass-transfer coefficient is enhanced for pseudoplastics and depressed for dilatants compared to the situation for Newtonian fluids. Some preliminary experimental results in support of the analysis are presented.     

非牛顿流体中的气泡行为

非牛顿流体广泛存在于各学科领域（如化工、食品和生物医学等）,也与许多工业过程及人类的生命过程密切相关。非牛顿流体中的气泡行为直接影响流体传质、传热及化学过程的快慢。因此,了解和研究非牛顿流体中的气泡行为具有重要意义。本文分别从气泡生成、聚并和破裂3个方面对非牛顿流体中气泡行为的研究进展进行评述。     

New Nomographs for Estimating Pressure Drop of Non-Newtonian Fluids Through Pipes And Annuli

In this study, the flow equations of non-Newtonian fluids through pipes and annuli have been derived using the Robertson-Stiff rheological model. From this, new and simple nomographs have been constructed to estimate the pressure-loss gradient directly for both flow-through pipes and annuli. Results from these nomographs gave excellent agreement with the results calculated from the flow equations.     

RHEOLOGICAL CHARACTERIZATION OF NON-NEWTONIAN FLUIDS WITH A NOVEL VISCOMETER

A hydrostatic head viscometer and its novel viscosity equation were developed to determine flow characteristics of Newtonian and non-Newtonian fluids. The objective of this research is to test capabilities of the hydrostatic head viscometer and its novel non-Newtonian viscosity equation by characterizing rheological behaviors of well-known polyethylene oxide aqueous solutions as non-Newtonian fluids with 60 wt.% sucrose aqueous solution as a reference/calibration fluid. Non-Newtonian characteristics of 0.3-0.7 wt.% polyethylene oxide aqueous solutions were extensively investigated with the hydrostatic head viscometer and its non-Newtonian viscosity equation over a 294-306 K temperature range, a 0.14-40 Reynolds number range, and a 55-784 s^-1 shear rate range at atmospheric pressure. Dynamic viscosity values of 60 wt.% sucrose aqueous solution were determined with the calibrated hydrostatic head viscometer and its Newtonian viscosity equation over a 3-5 Reynolds number range at 299.15 K and atmospheric pressure and compared with the literature dynamic viscosity value.