基于格子Boltzmann方法的液力变矩器导轮流场仿真

研究了基于格子Boltzmann方法(LBM)的液力变矩器导轮内流场数值计算理论与方法.首先,提出了LBM中处理旋转周期性边界条件的方法.然后,分析了LBM中各项参数对于计算稳定性以及计算效率之间的影响.为了保证粒子迁移与碰撞计算的稳定进行,必须合理选定弛豫时间τ,从而避免在计算过程中平衡态分布函数feq出现负值的情形.此外,在LBM中运用大涡模拟(LES)可以降低计算稳定性对于弛豫时间τ选取的限制,在一定程度上提高计算效率.最后,在开源代码Palabos的基础上进行功能拓展,实现导轮内流场的仿真计算,得到了导轮尾迹区域瞬时非定常流动分布特征.结果表明,LBM与传统计算流体力学(CFD)方法相比,液流对导轮作用力的计算结果在数值上较为接近.然而,使用LBM可以获得详细流场形成过程的时间历程以及局部复杂的流动细节.     

多相泵导轮的准三维正反问题研究

以速度矩作为控制参数,推导出多相泵导轮中均匀流模型的准三维反问题计算公式;基于两类相对流面理论及气泡的受力分析,推导出气、液两相在多相泵导轮中运动的准三维正问题的计算公式,提出一种对多相泵导轮内流场进行准三维数值计算的方法.通过计算导轮的准三维反问题,对其叶片形状进行了初步设计,并根据计算结果分析了导轮中的流动状况.对计算结果的分析表明,利用准三维方法进行多相泵导轮的正反问题计算是经济且有效的.     

双进双出型SCR脱硝反应器内导流板设计和数值模拟优化

为了优化某燃煤电厂215 MW锅炉的双进双出型选择性催化还原(SCR)烟气脱硝系统内流场与浓度场,提高脱硝系统的脱硝效率,应用计算流体力学方法对脱硝系统内流场与浓度场进行数值模拟。分别采用k-ε双方程模型和物质组分输运方程模型计算了烟气的湍流流动与氨浓度场分布,研究了原设计方案下脱硝系统内流场和浓度场分布规律,通过优化导流板结构与布置对脱硝系统进行了结构优化。研究结果表明,原设计方案中无导流板情况下,反应器内流场和氨浓度场分布严重不均;优化后,脱硝系统内第一层催化剂入口处烟气速度偏差与氨浓度偏差分别为6.86%和4.62%。     

动力系统流场计算动态网格生成模型研究

运用网格分块生成与整体集成方法,提出了复杂动力机械系统内流场三维流动计算网格自动生成模型,并以K100摩托车发动机扫描气系统为对象,实现了换气过程瞬态数值模拟动态网格的自动生成,数值计算结果,该方法可用于复杂机械系统内流场三维瞬态流动的数值计算。     

导叶可调式液力变矩器流场模拟与PTV验证

为研究导叶可调式液力变矩器的内部流动特性,以循环圆直径为320 mm导叶可调式液力变矩器作为研究对象.采用计算流体动力学(CFD)方法对其不同开度、不同工况下的内部流动状态进行数值模拟,并对相应的透明模型进行粒子跟踪测速(PTV)试验验证.同一开度下,随着转速比的增加,可调导轮内部液流速度增加,液流方向与叶片进口方向的夹角增大;在制动工况时,叶片工作面有漩涡现象,而空载工况时,叶片非工作面有漩涡产生.对比试验与数值模拟内流场结果,发现后者可以比较准确地预测导叶可调式液力变矩器的内部流动特性.该结论为研究导叶可调式液力变矩器内部流动状态,预测外特性及其设计优化提供了方法和依据.     

基于OpenFOAM的离心泵内部流动数值模拟

分析了离心泵内流模拟中存在的问题,指出开源CFD软件是提高离心泵内流模拟精度的必然选择.通过在开源计算流体力学软件OpenFOAM的求解器中添加GGI动静耦合处理程序,实现了OpenFOAM在泵内流数值模拟中的应用.应用修改后的OpenFOAM求解程序对一比转数为117.8的离心泵不同工况下的内流场进行数值模拟,并将数值计算结果与试验结果进行了对比,同时分析了叶轮内部流场的分布规律.研究结果表明,设计工况下的计算扬程相对误差最小,约为-3.5%,而小流量工况下误差最大-6.4%;各工况下的计算效率绝对误差范围均在-0.5%以内.这说明设计工况下的模拟结果优于非设计工况下的计算结果.同时,叶轮内部压力分布和相对速度分布规律符合离心泵内部流动的一般规律.     

变系数反应扩散方程的格子Boltzmann模型

研究了含变系数的反应扩散方程,构建了含弛豫时间函数τ(x,t)的D1Q3格子Boltzmann模型.为了能准确地恢复出此宏观方程,利用Chapman-Enskog展开和多尺度分析技术,推导出了各个方向的平衡态分布函数和弛豫时间函数τ(x,t)的具体表达式.数值计算结果表明该模型是稳定、有效的.     

XN295柴油机进气道模拟计算分析

利用CFD(computational Fluid Dynamics)软件对XN295直喷式柴油机的螺旋进气道的流场以及压力场进行模拟计算和分析.应用高雷诺数к-ε模型封闭雷诺方程,计算过程中,采用压力修正中的SIMPLE算法.数值模拟可以在较短的时间内获得关于流动的详细信息,从而降低了新产品开发和试验周期,为进一步分析气道内流场及各种参数提供可靠依据.     

有限体积法与LBM分区耦合模拟方腔自然对流

在已有的密度分布函数重构算子的基础上,推导出了温度分布函数的重构算子,解决了格子Boltzmann方法(LBM)与有限体积法耦合计算传热问题的关键难题.选二维方腔自然对流对耦合方法进行了考核.在瑞利数Ra=103~106范围内,耦合结果同商业软件FLUENT结果符合得很好,并且各物理量在耦合界面处连续且光滑过渡.通过残差曲线可以看出,耦合模型在密网格以及大瑞利数情况下,数值稳定性要好于单一LBM.     

纳米流体流动与传热过程的LBM并行计算

建立了描述纳米流体流动与传热过程的格子-Boltzmann模型,针对格子-Boltzmann方法（LBM）高度并行性的特点,用消息传递机制实现了平板间纳米流体流动与传热过程的LBM并行计算,分析了处理器数目与区域分解模式对计算效率的影响。结果表明,纳米粒子的微运动强化了流体与壁面以及流体内部的换热过程,LBM并行计算方法应用于纳米流体流动传热计算能够提高计算效率。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-