共查询到20条相似文献，搜索用时 234 毫秒
1.
针对工业中广泛应用的管壳式换热器,比较了几种壳侧流动的分析方法,并在此基础上提出了适宜于单相和气液两相流路分析法的壳侧单元流动模型。以主流、旁路流和泄漏流等各分流路的气液流量分布在稳态下应使壳侧流动的能量损耗达到最小的原则为基础,建立了壳侧气液两相流路分析法,给出了各流路的气液流量比例及错流区、窗口区压降的预测步骤,也给出了壳侧总压降计算式。建立的两相流路分析法预测结果与试验结果符合较好。 相似文献
2.
林万涛 《中国科学院研究生院学报》2004,21(3):402-406
针对非线性发展方程的非守恒格式 ,以二维非线性浅水波方程为例 ,给出了计算稳定的必要性条件 .在数值试验的基础上 ,进一步讨论了非线性发展方程非守恒格式与初值之间的关系 .理论分析和数值试验证明 ,非守恒格式的计算稳定性不仅与格式的结构有关 ,而且还由初值及其偏导数的形式所决定 相似文献
3.
大庆油田深层气井多为大型压裂井,气水两相流气井较多,在进行产能预测时,尤其是试采井的中长期产能预测时,用单相流方法预测,预测结果误差很大.本文采用黑油模型,考虑气水两相流动,建立了气水两相流的数学模型及其渗流方程,实际应用了11口井,按产量误差在20%以内为符合计算,符合率为72.7%. 相似文献
4.
流压远低于饱和压力时,在油井附近形成脱气圈,渗流条件发生变化,地层内两相流变为油气水三相流。在原油脱气情况下,油相相对渗透率不仅是含水饱和度的函数,也是含气饱和度的函数,因此用油水两相相渗曲线计算的采液指数存在较大误差。本文提出了用油层气油比修正采液指数,计算不同含水条件下采液指数的方法。 相似文献
5.
针对煤矿用多级耐磨离心泵中固液两相流动,假定固相颗粒浓度不变,结合SST湍流模型、Euler-Euler非均匀多相流模型进行非稳态计算,主要分析颗粒粒径变化引起的流动演变规律.结果表明随着粒径的增大,叶轮内固体颗粒逐渐向压力面转移,正导叶叶片凸面方向的固体颗粒数量逐渐减少,从而减弱了对壁面的磨损,反导叶内固体颗粒逐渐向叶片凹面聚集.正导叶和过渡区域的湍流动能整体随着粒径的增大而逐渐增大,而反导叶叶片内的湍流动能总体随着粒径的增大而减小.固体颗粒粒径的增大对内流场压力波动的影响,随着级数的增加而逐渐减弱.此分析结果为多级离心泵内的固液两相流动研究提供了参考依据. 相似文献
6.
针对高浓度气固两相射流,本文采用连续介质耦合模型,借助势流理论,推得两相射流场的稳定性控制方程,通过数值计算,得么了不同固粒容积系数和等效斯托克斯数下气固两相射流的频率曲线,在分析计算所得频率曲线的基础上,得么了关于固粒不同属性对射流场稳定性影响的结论,这些结论对于工程实际中人工控制高浓度两相射流具有理论指导意义。 相似文献
7.
8.
为研究和认识多种储层中弹性波的波场特征,以利于多波地震资料解释,高精度数值模拟是有效的方法之一.本文在弹性波方程基础上,采用高阶交错网格有限差分技术模拟地震波在各向同性介质和各向异性介质中的传播,可得到不同类型介质的弹性波场.同时,文中也分析了各向异性系数对多波波场特征的影响.通过对高精度数值模拟得到的波场快照对比研究表明,该方法可有效获得高精度弹性波正演结果,为研究各种复杂介质中弹性波的波场特征和传播规律奠定了基础. 相似文献
9.
<正>在有水气藏中,水的流动状态决定了气井产能方程的形式。水在砂岩气藏中通常为层流流动,以此为基础,本文推导了水服从达西流动、气服从非达西流动的有水气井二项式产能方程。分析了不同水气质量比对IPR曲线的影响,供给边界半径、表皮系数对气井无阻流量的影响,不同水气质量比或者不同井底流压下,含水饱和度随渗流半径的分布。通过分析得出:水气质量比越小,气井的产量越高;合理地减小井距,改善井底附近的地层,都将增大气井的产 相似文献
10.
本文采用数值模拟计算的方法,结合油藏流体质量守恒方程和渗流连续性方程,建立了三维油水两相流体渗流模型;结合水平井筒内流体动量方程和质量守恒方程建立了水平井变质量流动压降模型;根据井壁处流量一致和压力相等原则,将上述模型耦合起来,给出定压内边界条件下的求解方法,并用Eclipse软件对耦合模型进行验证,模型具有较高的准确性。 相似文献
11.
This paper presents a method for the evaluation of the tensile strength of composite materials made of a soft matrix with hard inclusions. The tensile strength is calculated as the force per unit area required for the onset of plastic flow in the material. In addition to the tensile strength, the severity of the core deformation and the rate of void formation are also estimated. The results are based on an upper-bound analysis with a two parameter family of velocity fields which accounts for both non-homogeneity of deformation and void formation.The model of the composite and the family of the velocity field used here have already appeared in published articles. Moreover, the application of the present method to estimate the tensile strength in cases when ductile deformation prevails (i.e. when there is no void formation) would lead to the same results as in the previous studies based on the same model and velocity fields.New here is the completeness of the analysis. All possible flow patterns, including for the first time void forming flows, were considered. This made it possible to show that the conditions required to ensure that one or another flow pattern prevails (i.e. those conditions found here and in other articles based on the same model) are not only necessary but also sufficient, at least from a theoretical point of view.The results of this paper have not yet been confirmed experimentally. Although the general trends are in the expected direction, so far no attempt has been made to find the degree of correlation between the theory and the behavior of real materials. 相似文献
12.
【目的/意义】从引文内容视角探究引文网络的拓扑结构及其组成要素的知识属性与引文网络中知识流动
效应间的关系。【方法/过程】首先,在阐述引文内容视角下引文网络知识流动主要特征的基础上,从静态特征属性
和动态结构属性2个方面构建了知识流动的演化动力模型;然后,依据影响引文网络中知识流动效应的主要因素,
从知识吸收效应、知识叠加效应和知识成本效应3个方面构建了知识流动效应函数的数学模型;最后,借鉴描述知
识溢出效应的蜂巢模型及其修正模型提出了知识流动效应系数的计算方法。【结果/结论】运用Netlogo设置演化动
力模型的初始参数,并通过仿真实验剖析各因素对知识流动效应系数的影响机理。文中方法可为客观反映引文网
络中的知识流动规律与模式,并揭示引文网络中的知识流动效应提供一套可参考的实证模型。【创新/局限】本文通
过计算实验方法从理论上较为系统地分析了引文内容视角下引文网络的知识流动效应,得出了一系列结论,但并
未结合实际题录数据的计算结果进行对比和优化。 相似文献
13.
14.
基于系统动力学构建了经济-社会-自然复合影响下区域人才流动的动力学模型,并以天津市为实证案例,对其人才流动趋势进行定量化动态仿真与模拟。通过调节模型的决策变量,设定了天津市5种人才流动的情形方案,一是通过设计3种人才政策优先级情形,得到经济、社会和自然三类影响因素对天津市人才流动的影响强度排序,即社会公共服务的影响强度最大,经济次之,自然环境最小；二是通过设计2种人才政策导向情形,预判了天津市更适宜采用生态宜居环境导向型发展道路。政策仿真实验的结果可为天津市未来规划、治理和发展提供决策支持,也证明了该模型方法应用于其他地区具有可行性。 相似文献
15.
16.
17.
In a crystalline material, structural defects such as dislocations or twins are well defined and largely determine the mechanical and other properties of the material. For metallic glass (MG) with unique properties in the absence of a long-range lattice, intensive efforts have focused on the search for similar ‘defects’. The primary objective has been the elucidation of the flow mechanism of MGs. However, their atomistic mechanism of mechanical deformation and atomic flow response to stress, temperature, and failure, have proven to be challenging. In this paper, we briefly review the state-of-the-art studies on the dynamic defects in metallic glasses from the perspective of flow units. The characteristics, activation and evolution processes of flow units as well as their correlation with mechanical properties, including plasticity, strength, fracture, and dynamic relaxation, are introduced. We show that flow units that are similar to structural defects such as dislocations are crucial in the optimization and design of metallic glassy materials via the thermal, mechanical and high-pressure tailoring of these units. In this report, the relevant issues and open questions with regard to the flow unit model are also introduced and discussed. 相似文献
18.
M.M. Mortula 《Journal of The Franklin Institute》2011,348(7):1627-1637
An innovative hydraulic structure was proposed for passage of fish in surface water. The structure consisted of identical ‘cells’ throughout its length and was designed to create coupled spatially varied flow for optimization of depth and velocity of water. The objective of this paper was to simulate the hydraulics of a single cell of this fish passage structure. A numerical model was developed to simulate the water surface profiles and longitudinal variation of 1-D velocity through one cell. The transition in the water surface profile between longitudinally adjacent cells (chamber) was also investigated. It was found that numerical convergence was usually achieved after three iterations with 2% discretization. The difference in depth arising from cell vs. chamber analysis was found to be small. The experimental results indicated turbulence in the water surface. The water surface profile matched the results obtained from numerical results. However, there were errors observed in estimation of flow rate. It is concluded that the mathematical approach used for the numerical simulation is reliable and can be used to analyze coupled spatially varied flow for any hydraulic structures aimed at controlling depth and velocity of water. Innovative approach to the interface between can potentially be used to achieve hydraulic goal of any structure. 相似文献
19.
20.
电子商务教学具有非常强的实践性,要求学生在了解电子商务相关理论知识的同时,也应该具备熟练运用网络进行电子商务活动的实践技能.因此,电子商务专业必须具备适合实践教学的网络环境和模拟实训系统.电子商务模拟实验系统在设计与实现过程中,采用了B/S模式开发,能够综合体现信息流、资金流、物流运作特点.本系统具有网上银行、CA认证、B2C交易中心、B2B交易中心、C2C交易中心、学生实验测评系统、系统后台管理等功能,重点突出了实战性、开放性的原则. 相似文献