Parametric study of gas−liquid two-phase flow field in horizontal stirred tank

Based on Fluent software,the gas−liquid two-phase flow in the horizontal stirred tank was simulated with SST k−ωturbulence model,Eulerian−Eulerian two-fluid model,and multi-reference flame method.The mixing process in the tank was calculated by tracer method.The results show that increasing the rotating speed or gas flow is conducive to a more uniform distribution of the gas phase and accelerates the mixing of the liquid phase.When the rotating speed exceeds 93 r/min,the relative power demand remains basically constant.The change in the inclination angle of the upper impeller has minimal effect on the gas phase distribution.When the inclination angle is 50°,the relative power demand reaches the maximum.An appropriate increase in the impeller distance from the bottom improves the gas holdup and gas phase distribution but increases the liquid phase mixing time.

TWO-PHASE FLOW FOR A HORIZONTAL WELL PENETRATING A NATURALLY FRACTURED RESERVOIR WITH EDGE WATER INJECTION

This paper examines the two-phase flow for a horizontal well penetrating a naturally fractured reservoir with edge water injection by means of a fixed streamlinemodel,The mathematical model of the verical two-dimensional flow or oil-water for a horizontal well in a medium with double-porosity is established ,and whose accuratesolutions are obtained by using the characteristic method .The saturation distributionsin the fractured system and the matrix system as well as the formula of the time of water free production are presented .All these results provide a theoretical basis and a computing method for oil displacement by edge water from naturally fracturedreservirs.

Numerical Predictions of Laminar Forced Convection Heat Transfer with and without Buoyancy Effects from an Isothermal Horizontal Flat Plate to Supercritical Nitrogen

Numerical predictions are made for Laminar Forced convection heat transfer with and without buoyancy effects for Supercritical Nitrogen flowing over an isothermal horizontal flat plate with a heated surface facing downwards.Computations are performed by varying the value ofΔT from5 to 30 K and P_(∞)/P_(cr)ratio from1.1 to 1.5.Variation of all the thermophysical properties of supercritical Nitrogen is considered.The wall temperatures are chosen in such a way that two values of Tw are less than T∗(T*is the temperature at which the fluid has a maximum value of Cp for the given pressure),one value equal to T∗and two values greater than T∗.Three different values of U∞are used to obtain Re∞range of 3.6×10_(4)to 4.74×10^(5)for forced convection without buoyancy effects and Gr_(∞)/Re^(2)_(∞)range of 0.011 to 3.107 for the case where buoyancy effects are predominant.Six different forms of correlations are proposed based on numerical predictions and are compared with actual numerical predictions.It has been found that in all six forms of correlations,the maximum deviations are found to occur in those cases where the pseudocritical temperature TT∗lies between the wall temperature and bulk fluid temperature.

On study of horizontal thin film flow of Sisko fluid due to surface tension gradient

The present paper is concerned with the steady thin film flow of the Sisko fluid on a horizontal moving plate, where the surface tension gradient is a driving mechanism. The analytic solution for the resulting nonlinear ordinary differential equation is obtained by the Adomian decomposition method （ADM）. The physical quantities are derived including the pressure profile, the velocity profile, the maximum residue time, the stationary points, the volume flow rate, the average film velocity, the uniform film thickness, the shear stress, the surface tension profile~ and the vorticity vector. It is found that the velocity of the Sisko fluid film decreases when the fluid behavior index and the Sisko fluid parameter increase, whereas it increases with an increase in the inverse capillary number. An increase in the inverse capillary number results in an increase in the surface tension which in turn results in an increase in the surface tension gradient on the Sisko fluid film. The locations of the stationary points are shifted towards the moving plate with the increase in the inverse capillary number, and vice versa locations for the stationary points are found with the increasing Sisko fluid parameter. Furthermore, shear thinning and shear thickening characteristics of the Sisko fluid are discussed. A comparison is made between the Sisko fluid film and the Newtonian fluid film.

TWO－PHASE FLOW FOR A HORIZONTAL WELL PENETRATING A NATURALLY FRACTURED RESERVOIR WITH EDGE WATER INJECTION

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Experimental Acoustic Determination of the Void Fraction in Two-Phase Flow in Horizontal Pipelines

In multi-phase flows, the phases can flow and arranged in different spatial configurations in the pipe, which called flow patterns. This type of flow is found in the oil, chemical and nuclear industries. For example, in the production and transport of oil and gas, the identification of the flow patterns are essential for answering those questions which are related to the economic return of the field, such as, measuring the volumetric flow, determining the pressure drop along the flow lines, production management and supervision. In offshore production, these factors are very important. This paper presents a new method for measuring the void fraction in horizontal pipelines, taking the air as gas in water-air two-phase flow. Through acoustic analysis of the frequency response of the pipe, the method gets the parameters to changes in runoff regime, in an experimental arrangement constructed on a small scale. The main advantages are the non-intrusive characteristic and easy to implement. The paper is composed of a qualitative experimental evaluation and transducers （microphone） which are used to analyze variations in the response accompanying variations in void and flow pattern changes. Changes are imposed and controlled by a two-phase flow experimental simulation rig, including a measurement cell constituted of an external casing that can isolate the measurement from the environmental background noise fitted with acoustic pressure transducers radially arranged, and the impact of a monitored excitation mechanism. The signals which captured by the microphones are processed and analyzed by checking their frequency contents changes according to the amount of air in the mixture.

Mixed convection heat transfer in horizontal channel filled with nanofluids

The laminar fully developed nanofluid flow and heat transfer in a horizonal channel are investigated. Highly accurate solutions for the temperature and nanopavticle concentration distributions are obtained. The effects of the Brownian motion parameter Nb, the thermophoresis parameter Nt, and the Lewis number Le on the temperature and nanoparticle concentration distributions are discussed. The current analysis shows that the nanoparticles can improve the heat transfer characteristics significantly for this flow problem.

Simulation of Hydrophobicity Evaluation and Structural Optimization Design Method for Micro-Array Units

In recent years, researches published on hydrophobic materials increase rapidly, wherein the method for changing hydrophobicity by modifying a micro-array structure on the surface of the material also has been proposed. Of course, if it is possible for us to quantitatively analyse and evaluate hydrophobicity of different structures of one certain material at first, this task will greatly optimize the design of actual structures. In this work, we used the algorithm for Laminar Two-Phase Flow, Horizontal-set method integrated in COMSOL to build two single-pore simulation structures in different shapes and simulated the behaviour of the liquid transition from Cassie-state to Wenzel-state during the impregnation process. After that, the intrinsic contact angle of Structure T (a porous structure with a T-shaped sectional profile) was obtained under a certain pressure which maintained liquids in Cassie-state. Meanwhile, two equilibrium states of the liquid-air interface as well as two different patterns of the equilibrium state disrupting were found in Structure R (a porous structure with a Chamfered T-shaped sectional profile). Simulation results show that the modelling method can be applied for simulating the hydrophobicity of different porous structures and optimizing the procedures for the design of the micro-array efficiently.

改进型INBA冲渣工艺在柳钢2号高炉的应用

针对INBA法中普遍存在的水回路中细渣多、热水池积渣严重以及各系统管道、泵阀磨损严重等问题,介绍结合了INBA法和平流沉淀法的改进型渣处理工艺,及其在柳钢2号高炉的应用特点和效果。

改进型INBA冲渣工艺在柳钢2号高炉的应用

针对INBA法中普遍存在的水回路中细渣多、热水池积渣严重以及各系统管道、泵阀磨损严重等问题,介绍结合了INBA法和平流沉淀法的改进型渣处理工艺,及其在柳钢2号高炉的应用特点和效果。

IDDES方法模拟风切变下大型水平轴风力机流场特性

为研究风切变条件下大型水平轴风力机流场特性,以NH 1500 kW大型水平轴风力机为研究对象,运用计算流体力学中模拟流场精度较高的IDDES(改进延迟分离涡)方法,分析流场内瞬时速度分量、脉动速度和风力机输出功率。结果表明:风轮平面周围流场速度波动大,轴向速度在风轮旋转边界以外的区域会增大,在旋转边界以内的区域会亏损;脉动风速频谱特性在低频区与风轮转频的整数倍相关,风力机功率呈余弦形式输出并满足湍流谱特性。

基于压差法的水平井岩屑床轴向运移规律研究

为了明确长水平段水平井旋转钻进工况下水平段岩屑床的轴向运移规律,开展了基于压差法的水平井岩屑运移试验。利用设置在井筒轴向不同位置的多个压差传感器,测量井筒的瞬时压降,用来表征岩屑床在井筒中的轴向分布,并据此计算了岩屑床运移速度,分析了流体密度、排量、转速对岩屑床运移速度和压降的影响规律。结果表明:该方法能够表征岩屑床运移特征,精细刻画了岩屑床在井筒轴向位置的分布;岩屑床运移速度与流体密度、排量和转速呈正相关关系;排量增大,可显著提高岩屑床运移速度,但压降迅速增大限制了加快清岩的最大排量;转速增大,能够提高岩屑床运移速度,且对井筒压降基本没有影响。研究结果明确了水平井岩屑床的轴向运移规律,为井下岩屑床轴向分布测量提供了理论基础,并有助于规避井筒压力复杂和卡钻等风险。

流动对比法在水平井生产测井解释中的研究和应用

由于水平井多相流体分布复杂、流动形态多变,导致生产测井数据难以处理出地层的产液剖面,尤其是脚跟回流和筛管完井管外流等复杂因素的影响。该文提出了水平井生产与相同井眼部位的流相和流速的对比,判断之间层的产出,称之为流动对比法。水平段高部位与高部位对比,低部位与低部位对比,上坡与上坡对比,下坡与下坡对比,脚跟的回流段则计算回流段上下部位流动剖面,对比判断此段是否有产出。经过多口井资料处理的结果表面,流动对比法消除了水平井高低部位、上坡、下坡、脚跟回流对测井曲线解释的影响,使水平井生产测井曲线可进行定性、定量解释。该方法分析出来的地层产液剖面,为后续的酸化、堵水提供了基础数据。给出了此方法需要的测前设计的关键点。讨论了流动对比法的优缺点和推广应用中注意的事项。

水平井水平段最优长度设计方法研究

由于水平井水平段内摩擦损失的缘故，如果水平段内压降和油藏压降相当，导致水平段末端压降很小或者为零，这种现象常常出现在高渗透层的低压降生产油藏和生产压差受到限制的锥进油藏。因而研究水平井最优长度设计方法对水平井开发方案设计具有指导意义。本文分三种情况（底水油藏、气顶底水油藏、气顶油藏）建立了油藏内流动模型、井筒内流动模型、水平井水平段最优长度数学模型，在建立模型过程中，考虑了水平段内流动状态（层流、紊流）和管壁相对粗糙度对摩擦损失和水平井产能的影响，最后通过实例计算得到了几个结论。

气藏水平井携液临界流量计算

液滴在水平井筒中的受力情况与垂直井筒中截然不同,根据垂直井筒中质点力学分析获得的计算气井携液临界流量的Turner公式及其修正式不再适用于水平井。根据水平井筒内液滴质点分析理论,推导出水平气井的携液临界流量公式。与水平管气液两相流态机理计算得到的携液临界流量结果的对比结果表明,用质点分析理论计算得到的携液临界流量比气液两相流态机理计算结果要偏于乐观,且其流态正处于环状流和雾状流的过渡区。因此,在实际应用中,用质点分析理论计算的结果可根据生产井实际情况在一定范围内进行调整。

水平转弯颗粒流的离散元模拟

为了研究水平转弯输运物料时颗粒流的动力特性以及物料颗粒对输送带的作用机理,在离散元理论基础上,采用非线性HertzMimdlin接触模型,建立了水平转弯输运的离散元模型。以不同的角速度模拟测试颗粒平均速度,与计算的带中央切向速度相比,获得了一组比较接近的数字。说明所采用的接触模型和材料的物理参数是正确的。研究了两组不同的颗粒单元、4种滚动摩擦系数下的颗粒动力特性,发现颗粒平均速度与颗粒单元、滚动摩擦系数无关。通过输送带加速运行,模拟了料流分布以及料流对输送带外侧压力分布的影响。结果表明,随着带速的增加,带外侧平均压力逐步增加,而最大压力非线性地剧增。

一种新的水平井产量计算公式

解析法是水平井产量研究的重要方法,是从数学模型出发,通过相应的假设条件,简化方程的初始、边界条件,利用保角变换、镜像映射、势的叠加原理及等值渗流阻力法等得到水平井的产量公式并求出解析解。在调研水平井计算公式发展历史和研究现状的基础上,通过对水平井泄油体的简化、分解和流场的三维处理,遵循水平井远井区域水平平面渗流和近井区域垂面径向流的基本渗流规律,运用等值渗流阻力法推导出一种新的水平井产量公式,通过与常用水平井产量公式在经典算例下的对比研究表明,该公式是合理可靠的。

水平井井筒变质量流动压降计算新模型

为了使水平井变质量流压降模型更具合理性和准确性,更有效地分析油井产能和生产动态,通过回顾和分析以往关于水平井筒压降模型的计算理论与方法,利用现有实验数据回归分析建立了一种新的射孔完井压降计算回归模型,该模型能够实现射孔完井孔密、相位角连续变化时综合摩擦系数的求取和井筒压降的计算。通过实例对比分析可以看出,该模型和目前常见模型的计算精度较为接近、计算结果较为合理。该模型的提出可以为进一步改进油藏渗流与井筒流动耦合模型的理论研究提供参考。

潮汐河口平面二维非恒定流数值模拟

本文基于三角形网格划分 ,采用有限元法 ,建立了平面二维非恒定潮流数学模型。采用了质量集中、压缩存储的处理方法和“预估校正”的时间推进算法 ,较好地解决了有限元计算存储量和计算速度问题。对长江口南北支河段进行了验证计算 ,结果表明模型能较好模拟长江口南北支河段的潮流运动情况 ,且计算稳定性好、速度快。

水平井探测半径及其计算方法

目前,油气井探测半径的计算方法均是针对直井,对于水平井测试或生产过程中的探测范围的研究较少,而水平井探测范围又是评价井控储量大小、确定水平井对油气藏的控制程度的重要参数。水平井在生产时仅在近井地带与直井的渗流方式不同,而在远处均为平面径向流动。据此,可以将水平井的渗流问题转化为虚拟直井的渗流问题,利用前人将水平井段简化为拟圆形生产坑道的设想,借鉴直井探测半径定义和评价方法,提出了水平井探测半径的概念,并将水平井探测半径的问题转为虚拟直井探测半径的问题,解决了水平井探测半径的计算难题。运用该方法可以优化油气藏水平井设计,并根据生产动态实时评价水平井对储量的动用程度、正确评估水平井开发的技术优势。