气液两相流流量变化瞬态特性

在气液混输管线中常发生流量变化引发的瞬态过程,在大型多相流实验环道上进行了流量变化的瞬态实验.气量突增产生压力过增量,它的产生与流型有关：分层流的过增量是由于气体的惯性;在气团流和段塞流下则是由于气体压缩性和液体惯性的联合作用.气量突降时,膨胀波沿程传播.气量变化的瞬态过程可能出现对应准稳态变化没有出现的流型.与气量突变相比,液量突变引起的压力和流型变化较平缓,瞬态效应小.流量变化后产生沿线传播的压力波和空隙波,二者与流型相关,决定瞬态过程的发展.压力变化的传播速度在气量变化时等于声速,在液量变化时等于空隙波波速.     

管道水力絮凝过程的动力学和机理研究

本文通过对高浊度原水的大量烧杯絮凝和管道絮凝水力参数与絮凝效果实验及其结果对比,分析了管道絮凝过程的行为规律,并对其絮凝过程动力学和机理作了深入分析研究,得出了若干对管道絮凝器的研制有益的结论。     

旋转椭圆截面螺旋管道内的二次流

根据张量分析推导出旋转螺旋直角坐标下Dean问题的控制方程 ,以Dean数D为小参数采用摄动方法获得椭圆截面旋转螺旋管道内黏性流动的摄动解 ,结果表明该流动受 4个参数的影响 :D ,η,σ ,λ.并讨论了各个参数变化时截面二次流形态的复杂变化 .结果还表明一阶挠率项不影响圆截面旋转螺旋管道内的黏性流动.     

SIMULTANEOUSLY DEVELOPING LAMINAR FLOW AND HEAT TRANSFER IN THE ENTRANCE REGION OF A CIRCULAR TUBE WITH CONSTANT WALL TEMPERATURE

The developing flow and heat transfer in the entry region of a heated circular tube is analyzed for the case of constant wall temperature. An integral or boundary-layer solution is presented which has a number of advantages over earlier Karman-Pohlhausen integral analyses. Thus, in the present analysis, the velocity and temperature distributions, the local and mean drag coefficients, and the local and mean Nusselt numbers approach their fully-developed values asymptotically. The new analysis is based on the hydrodynamic inlet-filled region concept originally proposed by Ishizawa (1966) and later adopted by Mohanty and Asthana (1978) to flow through a circular tube. This concept is extended to the combined entry-length problem by introducing a thermal transition region, herein called the thermally-filled region, between the thermal inlet boundary-layer region and the thermally fully-developed region. A thermal shape factor is also introduced which ensures smooth transition of all pertinent thermal quantities from the entrance region to the fully-developed region. Results for the variation of the local and mean Nusselt numbers with axial distance along the tube for Pr = 0.1,0.5,0.7,1,5, and 10 are presented. These results agree well with the numerical solutions of Hombeck (1965), Manohar (1969), and Hwang and Sheu (1974) and also with the correlations of Churchill and Ozoe (1973).     

管内稠密气固两相流数值模拟计算:颗粒动力学方法

基于稠密气固两相流流体动力学模型、颗粒动力学的颗粒湍动能模型 (KTGF)和气体湍动能模型(SGS) ,模拟计算结果得到了实验研究所揭示的环 -核流动结构 .模拟计算与Miller和Gidaspow的实验结果进行了比较 ,颗粒相浓度、速度和颗粒相动力黏性系数分布与实验值基本吻合 .     

垂直圆管内湍流泡状流的数值研究

在经典Euler/Euler型水动力模型基础上,引入考虑不同直径气泡的种群平衡方程来描述气液两相泡状流,对液相和气相分别建立了基本方程,通过对气泡的受力分析并考虑气泡之间聚合和破碎效应后给出了本构方程,建立了封闭的双流体模型并用于垂直管道湍流泡状流的三维数值模拟.模型预测值与实验数据的比较结果表明该模型能较好地模拟垂直管道湍流泡状流中的相含率分布、速度分布、湍动能分布、气泡直径分布以及气泡直径分布的演变过程.     

软土地基中某埋地玻璃钢原水管爆管事故力学性能分析

近年来,南方某市供水管网埋地大口径玻璃钢原水管发生了6次较为严重的爆管事故,威胁了该管网的供水安全。为了研究管道出现事故的原因,对爆管处管道试样进行了力学性能试验,包括试样的拉伸、压缩、弯曲试验,同时根据管道所处地质条件,结合管道自身的力学性能参数对埋地玻璃钢管的受力性能进行理论计算和分析,包括管道长期变形、强度和管壁截面稳定。根据爆管处管道试验和理论计算结果推断管道爆裂的原因,同时提出相应建议以减少爆管事故的频繁发生。     

硬质塑料管材阻隔技术研究

介绍塑料的阻隔原理及提高塑料阻隔性能常用的两种方法,即层状共混方法和多层共挤方法。从阻隔机理、配方、成型工艺等几方面介绍了阻隔性硬质塑料管材层状共混的成型方法,并对制备层状共混物的影响因素进行了初步探讨。研究分析表明,制品中的层状阻隔成分可大大提高制品对烃类液体的阻隔能力。与多层共挤技术相比,层状共混技术可以使塑料阻隔性改进和挤出成型一次完成,而且工序简单,易于应用。     

管道流动絮凝研究进展及其分析

本文着重从絮凝动力学致因、搅拌强度评价参数和絮凝过程滞留时间、絮凝效果综合评价指标以及絮凝剂选用和投加方式等诸方面概述管道流动絮凝研究的国内外进展并对其进行了分析探讨。     

水煤浆气化炉激冷室下降管内流动与传热数学模拟

引　言由于工程经验不足及技术方面的原因 ,煤气化设备经常出现故障而导致工厂被迫停产 ,从而造成巨大的经济损失[1] .而煤气化设备中的核心设备气化炉是易损坏的设备 .经分析 ,气化炉激冷室结构设计不够合理 .本文以水煤浆气化炉激冷室为研究对象 ,采用ｋ ε模型[2 ] 、四通量     

TURBULENT FLOW IN A PIPE WITH INTERMITTENT ROUGH PATCHES: AN ANALOGUE OF ANNULAR TWO-PHASE FLOW

The response of turbulent pipe flow to sudden changes in wall roughness and flow cross-sectional area has been studied experimentally and numerically. Changes typical of those encountered by the gas phase in annular gas-liquid flow have been considered. The results show that the flow field and the pressure field can be significantly distorted at these transitions. Good agreement has been obtained between the measured results and those calculated using the Harwell-FLOW3D computational fluid dynamics (CFD) code.     

EXACT SOLUTIONS FOR THE UNSTEADY FLOW OF A BURGERS' FLUID BETWEEN TWO SIDEWALLS PERPENDICULAR TO THE PLATE

This article presents the exact solutions for the unsteady flow of an incompressible Burgers' fluid induced by the impulsive motion of a plate between two sidewalls perpendicular to the plate. Employing the Fourier sine transforms, the expressions for the velocity field, the tangential stresses, and the volume flux are obtained. The obtained solutions satisfy all imposed initial and boundary conditions and in the absence of the sidewalls reduce to the solutions corresponding to the flow over an infinite flat plate. The effect of the material parameters on the velocity field and the tangential stress at the bottom wall is spotlighted by means of the graphical illustrations.     

THE COLLISION RATE OF PARTICLES IN TURBULENT FLOW

A review of previous derivations of particle collision rates in turbulent fluid flow shows that these are applicable only to limited cases. A more general derivation is given, taking into account the effects of the inertia of the particles and the difference in densities of the fluid and the particles. A universal solution for the relative velocity of two particles due to turbulent accelerations in a gaseous or liquid system is presented. In gaseous systems the acceleration mechanism becomes predominant at particle sizes far below the Kolmogorov microscale of turbulence. In liquid systems, the particle inertial and added mass effects become important above the Kolmogorov microscale. Here the particle collision rate cannot be estimated from the fluid turbulent velocity fluctuations only.     

聚乙烯多元体系的熔体流动速率研究

研究PE二元混合体系、PE三元混合体系的MFR与组分的MFR及组分含量之间的关系，建立了定量关系式，并绘制了PE混合体系的MFT与组成关系图。     

MODELING OF THE REACTANT CONVERSION RATE IN A TURBULENT SHEAR FLOW

Results are presented of direct numerical simulations (DNS) of a spatially developing shear flow under the influence of an infinitely fast chemical reactions of the type A + B → Products. The simulation results are used to construct the compositional structure of the scalar field in a statistical manner. The results of this statistical analysis indicate that the use of a Beta density for the probability density function (PDF) of an appropriate Shvab-Zeldovich mixture fraction provides a very good estimate of the limiting bounds of the reactant conversion rate within the shear layer. This provides a strong justification for the implementation of this density in practical modeling of non-homogeneous turbulent reacting flows. However, the validity of the model cannot be generalized for predictions of higher order statistical quantities. A closed form analytical expression is presented for predicting the maximum rate of reactant conversion in non-homogeneous reacting turbulence.     

圆管内含颗粒幂律流体的密相两相湍流

阐述了幂律流体控制方程的特点,研究了幂律流体的稠度系数和流动指数的变化对两相流动的影响.随着流动指数的增加,幂律流体在圆管中心附近的主流速度减小,同时颗粒相速度在圆管中心附近增大,而在管壁附近减小.随着稠度系数的增加,幂律流体和颗粒相的主流速度分布出现了与流动指数带来的影响相似的趋势.对带颗粒的幂律流体的两相流流动与液固两相流流动做了比较,幂律流体两相流的流体速度在管道中心附近的大部分区域比液固两相流的流体速度流动的速度大,而颗粒相的速度分布比较平坦.     

IDENTIFICATION OF LIQUID-LIQUID FLOW PATTERN IN A HORIZONTAL PIPE USING ARTIFICIAL NEURAL NETWORKS

Identification of flow pattern during the simultaneous flow of two immiscible liquids requires knowledge of the flow rate of each fluid as well as knowledge of other physical parameters like conduit inclination, pipe material, pipe diameter, viscosity of the oil, wetting characteristics of the pipe, design of the entry mixer, and fluid-fluid interfacial tension. This article presents an artificial neural network (ANN)-based novel technique to determine the liquid-liquid flow regime. This approach uses phase superficial velocities as input parameters, which are obtained from a specific set of data obtained from experimental investigations. Both experimental and ANN-based determinations of liquid-liquid flow pattern have been undertaken for a common data set and the results are compared to prove the effectiveness of ANNs in pattern recognition. A unique ANN architecture is identified with three hidden layers, and the inputs and outputs are modeled into binary form. Levenberg-Marquardt (LM) learning algorithm is used for training this neural network. The design details of the ANN, parameter modeling, and training aspects are presented.     

窑炉用风量的合理匹配

预分解窑系统窑炉用风量的合理匹配对于稳定系统的热工制度,提高熟料的产量、质量都至关重要,但不同的窑炉结构及不同的操作条件,窑炉对煤粉的环境也不尽相同,燃烧所需要的气体量也不同,根据预分解窑系统煤粉燃烧的的特点,结合国内几家预分解窑的实际生产情况,探讨了窑炉在正常运行条件下用风量,即一、二、三次风的风量大小,并根据某厂家在生产过程中为强化炉内煤娄的燃烧,而对三次风风门开度进行了再次调整后的现场检测结果,讨论了窑炉用风量的合理匹配问题及其对系统正常运转的重要性,指出生产中一定注意风的分配、窑炉用煤量的比例,并兼顾整个系统风、煤、料的匹配关系。     

水平直圆管内油气两相流的压降

对水平放置的内径为40 mm的有机玻璃管内的油气两相流进行了详细的实验研究,实验工质为46^＃机械油和空气.油相和气相折算速度分别为0.051～0.612 m•s^-1和0.024～50.64 m•s^-1,实验在室温下进行.采用Lockhart-Martinelli关联方法对各典型流型下的实验数据进行了整理,结合流动的具体情况对其中的关联参数C进行了重新定义,提出了基于典型流型的压力梯度计算模型,并对水平管内油气两相流的压降变化规律进行了分析和讨论.理论计算值与实验测量值吻合良好.