基于动态双重网格下喷动床滞止区流动特性CFD-DEM数值模拟

基于Fortran语言自行开发了基于动态双重网格方法下的喷动床内气固两相流动的CFD-DEM方法,同时开展了喷动床内径向混合实验与模拟研究,又结合单网格方法对喷动床内0~2.0 s内的滞止区特性进行对比分析,验证了动态双网格方法计算结果的准确性。然后利用动态双网格方法对不同进口气速下和不同初始堆积高度下的喷动床进行数值模拟研究,对滞止区颗粒流动过程进行追踪,结果表明：径向混合实验结果与数值模拟结果有很好一致性;在喷动床内存在一定的滞止区,滞止区内的颗粒流动性较差;初始堆积高度不变,随着进口速度的增加,滞止区高度下降速率和向喷口延伸速度无明显变化;进口速度不变,随着初始堆积高度的增加,滞止区颗粒下降速度随之增加,但其向喷口延伸速度逐渐变慢。     

搅拌槽内近桨区流动场的数值研究

利用滑移网格方法，采用三种不同密度的网格，计算了六直叶涡轮搅拌桨的三维流动场。利用数值方法得到了桨叶附近流动场中产生的尾涡，并将不同密度网格下的数值模拟结果与实验数据进行了比较。计算结果表明，在高密度的网格下可以清楚地观察到桨叶附近所产生的尾涡，其大小与实验结果一致，但尾涡衰减较快：叶端的径向与切向速度分布与实验值吻合较好，加密网格对最大径向及切向速度的预测精度有明显提高；即使采用很高的网格密度，对湍流动能的预测仍然偏低。     

地震波场数值模拟有限差分格式对比研究

在应用有限差分法地震波场数值模拟过程中,采用细网格剖分模型可以提高数值模拟的精度,但却降低了数值模拟效率。针对这一现象,本文分别对交错网格数值模拟和可变网格数值模拟进行研究,并对同一个二维复杂介质模型分别进行数值模拟计算,在不同的网格剖分方式下得出不同的地震记录。以此来比较交错网格与可变网格的计算效率与模拟精度,进而对实际生产提供借鉴。     

数值试井技术及在海拉尔油田贝301区块的应用

数值试井解释方法全面的考虑了油藏的地质因素和开发因素,较传统的试井解释方法更加的符合油藏的实际情况。数值试井解释技术是在试井分析领域内采用了数值分析技术,通过对整个复杂区域（包括井和油藏）进行网格划分,用合适的数值离散方法对有关压力的连续性方程的进行离散,从而生成离散方程组,再求解离散方程组,用求得的近似压力响应与实测的压力数据进行比较,得到解释参数,从而更好的评价复杂的油藏。针对海拉尔油田贝301区块的开发生产特点,对全面开发的油藏中生产井测试资料的分析应综合考虑地层和邻井生产动态的影响。     

基于八叉树自适应网格技术的LevelSet运动界面追踪方法

Level Set方法因能有效地处理界面处复杂的拓扑结构变化以及大变形问题,广泛应用于界面追踪领域。在Level Set方法追踪运动界面时引入八叉树网格技术,通过八叉树网格的细化和粗化技术减少计算网格数量和计算内存并提高计算效率和计算精度。因为八叉树网格为非均匀网格,其相邻网格的层数值可能不相同,所以不能直接采用WENO格式离散Level Set函数得到网格处的函数值,进而提出八叉树网格离散模型解决这一问题,并提出基于八叉树网格距离场重新初始化方法减少Level Set方法的质量损失,最后将基于八叉树网格技术的Level Set方法应用于两个给定速度场的运动界面模拟算例以及基准件方腔的铸造充型过程的模拟。模拟结果表明该方法可以提高界面的精度,同时改善质量守恒性。     

网格和数值格式对TBPBM-CFD模型模拟鼓泡塔的影响

基于气泡动力学属性的现有认识,把气泡分成大、小气泡,首次建立了完整的双气泡相-群平衡模型(TBPBM)以预测气泡尺寸.通过编写用户自定义程序实现了TBPBM模型、Luo破碎模型以及Prince 聚并模型,并耦合TBPBM与CFD双流体模型对直径440 mm鼓泡塔进行数值模拟,详细考察了网格与数值格式对TBPBM-CFD模型模拟结果的影响.结果表明,网格与数值格式对各物理变量的模拟结果影响非常大,特别是网格和体积分数方程对流项离散格式的影响最为显著.随着计算精度的提高,湍流耗散率和整体气含率分布梯度增大,气泡平均直径减少,大气泡所占气相比率降低,液相速度及气含率径向分布与实验值更趋吻合.     

数值试井方法研究

对于复杂形状、多变的非均质油藏以及多相流等常规试井问题,利用解析方法很难解决,用数值试井的方法可望得到很好的解决。文中提出了数值试井研究的五个主要内容,即参数拟合方法、数值模拟的精度控制、网格剖分技术、与常规试井方法的结合、试井资料的挖潜。同时指出了数值试井的优点与不足。     

数值试井的研究现状及展望

试井是油气田勘探开发过程中了解地层特性的一种广泛使用的技术。对于具体的试井问题,从广义上来说,可以分为解析试井和数值试井两大类。解析试井适用于一些地层和流体比较简单的情况,对于复杂形状、多变的非均质油藏以及多相流试井问题,解析解法尚无能为力,但用数值试井的方法可望得到很好的解决。文中提出了数值试井研究的六个主要内容,即参数拟合方法、数值模拟的精度控制、网格剖分技术、与常规试井方法的结合、试井解释范畴的拓宽和数值试井解释软件的研制,同时指出了有限元和边界元数值试井理论是数值试井发展的新方向。     

解析试井的挖潜——数值试井

对于复杂形状、多变的非均质油藏以及多相流等常规试井问题,利用解析方法很难解决,用数值试井的方法可望得到很好的解决.文中提出了数值试井研究的五个主要内容,即参数拟合方法、数值模拟的精度控制、网格剖分技术、与常规试井方法的结合、试井资料的挖潜.同时指出了数值试井的优点与不足.     

带底油(薄油环)凝析气藏数值模拟中混合网格的处理方法

带底油(油环)凝析气藏的数值模拟中,网格的划分对底油(油环)的描述起着很重要的作用。由于地层倾角的存在,常规的顺层网格经常会出现油气或油水界面在同一个网格内,甚至油气、油水界面在同一网格的情况,饱和度变化不连续,不能很好地描述油环油的分布;加密网格虽然在一定程度上减轻了这种现象,但是网格过多,影响数值模拟计算效率。本文针对底油(油环)的水平分布形态,建立了在气顶部分为顺层网格,底油(油环)和底水(边水)部分为水平网格的混合网格形式,很好地保证了底油(油环)的分布形态。同时,通过渗透率的转换,使水平网格部分的流体流动特性与地质上一致,有效地描述底水锥进薄油环以及油进入气藏的动态过程。通过对模型的模拟计算,验证了这种方法的可靠性。     

A new discretization of space for the solution of multi-dimensional population balance equations

In this work, a novel radial grid is combined with the framework of minimal internal consistency of discretized equations of Chakraborty and Kumar [2007. A new framework for solution of multidimensional population balance equations. Chemical Engineering Science 62, 4112-4125] to solve n-dimensional population balance equations (PBEs) with preservation of (n+1) instead of 2ⁿ properties required in direct extension of the 1-d fixed pivot technique of Kumar and Ramkrishna [1996a. On the solutions of population balance equation by discretization-I. A fixed pivot technique. Chemical Engineering Science 51, 1311-1332]. The radial grids for the solution of 2-d PBEs are obtained by intersecting arbitrarily spaced radial lines with arcs of arbitrarily increasing radii. The quadrilaterals obtained thus are divided into triangles to represent a non-pivot particle in 2-d space through three surrounding pivots by preserving three properties, the number and the two masses of the species that constitute the newly formed particle. Such a grid combines the ease of generating and handling a structured grid with the effectiveness of the framework of minimal internal consistency. A new quantitative measure to supplement visual comparison of two solutions is also introduced. The comparison of numerical and analytical solutions of 2-d PBEs for a number of uniform and selectively refined radial grids shows that the quality of solution obtained with radial grids is substantially better than that obtained with the direct extension of the 1-d fixed pivot technique to higher dimensions for both size independent and size dependent aggregation kernels. The framework of Chakraborty and Kumar combined with the proposed 2-d radial grid, which offers flexibility and achieves both reduced numerical dispersion and the ease of implementation, appears as an effective extension of the widely used 1-d fixed pivot technique to solve 2-d PBEs.     

模塑玻璃钢格栅发展趋势

本文介绍了模塑玻璃钢格栅的国内外发展现状,就其发展前景与趋势进行了预测,对该制品行业所面临的问题进行了分析、探讨,并从模塑玻璃多格栅的生产工艺、产品质量、品种、产品性能温度与研究,市场开拓等多方面提出了一些看法与建议。     

玻璃纤维格栅及在沥青路面中的应用

本文介绍了玻璃纤维土工格栅的性能特点，制造工艺及在沥青路面中的增强作用和简要操作方法。     

炉箅设计要适应造气技术发展需要

对比分析了以煤为原料合成氨厂造气炉采用单烧法较之混烧法,使用专用炉箅较之通用型炉箅的优势;探讨了专用炉箅的结构和高度对布风的影响以及专用炉箅的边型对破渣和排灰速度的影响;提出了改进专用炉箅设计的建议。     

蚀刻技术在VFD栅网制作中的突破

VFD栅网以其超细的线度和高度的均匀性，提出了蚀刻技术的新课题，促成了蚀刻技术的新突破。     

Assessment of k–ε models using tetrahedral grids to describe the turbulent flow field of a PBT impeller and validation through the PIV technique

In turbulence modeling, the RNG and Realizable models have important improvements in the turbulent production and dissipation terms in comparison to the Standard. The selection of the appropriate turbulence model has an impact on the convergence and solution in STRs, and they are used in mixing, multiphase modeling or as starting solution of transient models as DES and LES. Although there are several studies with the pitched blade turbine(PBT) impeller, most of them used the Standard model as representative of all k–ε models, using structured hexahedral grids composed of low number of cells, and in some cases under axial symmetry assumptions.Accordingly, in this work the assessment of the Standard, RNG and Realizable models to describe the turbulent flow field of this impeller, using the Multiple Reference Frame(MRF) and Sliding Mesh(SM) approaches with tetrahedral domains in dense grids, is presented. This kind of cell elements is especially suitable to reproduce complex geometries. Flow velocities and turbulent parameters were verified experimentally by PIV and torque measurements. The three models were capable of predicting fairly the pumping number, the power number based on torque, and velocities. Although the RNG improved the predictions of the turbulent kinetic energy and dissipation rate, the Realizable model presented better performance for both approaches. All models failed in the prediction of the total dissipation rate, and a dependence of its value on the number of cells for the MRF was found.     

The study of carbon-based lead foam as positive current collector of lead acid battery

The carbon-based lead foam was produced by electrodepositing a uniform and dense lead coating on lightweight carbon foam in fluoborate system under appropriate conditions. The cyclic voltammetry showed that its electrochemical properties resembled the metallic pure lead. A lead acid battery equipped with the carbon-based lead foam as positive current collector undergone a charge–discharge test. The battery had a high discharge capacity and a good cycling stability, which indicated that the carbon-based lead foam could serve as positive current collector. The three-dimensional net structure of carbon-based lead foam provides larger surface area than traditional lead alloy grids, thus enhances the specific capacity of lead acid battery. The carbon-based lead foam might be a promising substitute for lead alloy grids.     

子午斜交轮胎力学性能有限元分析

提出一种新型子午斜交轮胎结构,即将子午线轮胎胎侧部位的胎体帘线子午结构改为斜交结构,并利用有限元模型对子午斜交轮胎和子午线轮胎的特性进行对比分析.结果表明:与子午线轮胎相比,子午斜交轮胎的径向刚度较高;胎侧应变能密度分布较连续且相对均匀,且最大应变能较低;胎面横向接地压力分布较均匀、尤其是胎肩处的应力集中区域较小,接地印痕形状近似椭圆形;带束层边缘的剪切应变峰值较小.     

径向流固定床数学模型研究进展

简要阐述了径向流固定床反应器在化学工程中的重要性及研究该类流动问题的迫切性，回顾了文献中描述该反应器中流体流动的六类数学模型，提出了设计准则及均布措施，指出了存在的问题及解决的途径．     

The Development of a New Thermophoretic Precipitator for Scanning Transmission Electron Microscope Analysis of Ultrafine Aerosol Particles

A thermophoretic precipitator specifically for collecting ultrafine aerosol samples onto electron microscope support grids has been designed, and built. The precipitator has been designed to deposit particles of diameter less than 100 nm discretely onto support grids, with uniform deposition velocity across the size range. In addition, it has been designed to be compact, and portable. Preliminary investigations indicate it to give discrete deposits suitable for single particle analysis. Qualitatively, particle deposition velocity appears uniform between 4 and 30 nm, with a slight decrease towards higher diameters, although this is yet to be confirmed by comparison with reference particle size distribution analysis methods. Particle distribution on the microscope grid was shown to be uneven on a millimeter scale, but relatively even on a micrometer scale, enabling good characterization of the deposit.