基于正交试验的迷宫流道灌水器参数化设计研究

采用正交试验设计方法，取三角形迷宫流道灌水器的关键参数为因素，利用光固化快速成形技术制作出各参数组合的灌水器与外管一体化结构原型，并进行了灌水器水力性能的试验研究．流量和流态指数的极差和方差分析结果均显示出流道转角对流态指数的影响最显著，而流道单元数对灌水器流量的影响最大，这一结果有助于解决流道经优化后带来的流量增大问题．应用多元线性回归法拟合出灌水器流量系数和流态指数与参数的关系式，进而得到了流量与压力的回归方程．验证试验结果表明，回归方程能较好地预测迷宫流道灌水器流量与压力的关系，从而实现了灌水器参数化的结构设计．     

滑阀矩形节流槽阀口的流量系数

基于阀口流量压差特性试验和矩形阀口面积计算,对滑阀上矩形节流槽阀口的流量系数进行研究,获得滑阀矩形节流槽阀口流量系数及其变化规律.研究发现:滑阀矩形节流槽阀口流量系数与阀口开度、液流方向、截面深宽比和截面水力直径关系密切,阀口开度较小时流量系数接近于1,随着阀口开度的增大而逐渐减小,在阀口中间区段接近于常数,在接近全开度时流量系数又快速增大;流入节流槽方向的流量系数比流出方向大0.05~0.10;流量系数随矩形节流槽截面深宽比增大而增大,并随截面水力直径增大而有所增大.     

离心泵平衡腔泄漏量和压力的计算与试验研究

基于后密封环和平衡孔泄漏量相等原理,推导出了平衡腔泄漏量和压力的数学模型．对不同后密封环间隙和平衡孔直径时的后密封环进口压力、平衡腔压力、平衡腔泄漏量进行了系统测试,结果发现：增大后密封环间隙对后泵腔有降压作用,而对平衡腔有增压作用;增大平衡孔直径,后泵腔压力和平衡腔压力有不同程度的降低,但当密封环间隙较小时后泵腔压降效果不明显．计算得到了后密封环流量系数和平衡孔流量系数与比面积的试验曲线,后密封环流量系数随比面积增大而增大,而平衡孔流量系数随比面积增大而减小．给出了流量系数比与比面积的试验曲线,该曲线反映了后密封环间隙和平衡孔直径对平衡腔压力的耦合调节作用,具有重要工程应用价值．     

压力补偿灌水器分步式CFD设计与实验研究

为提高压力补偿灌水器的设计精度和研发效率,提出了一种压力补偿灌水器分步式CFD模拟方法。基于CAD建模、CFD分析软件Fluent和有限元分析软件An-sys,该方法可实现灌水器设计模型水力性能的模拟。采用这种方法,设计了一款直径12mm的圆柱压力补偿灌水器,并对其水力性能进行了模拟,得到了灌水器的预测压力-流量曲线。利用光固化快速成型技术制作出了实验样品,进行了水力性能实验,得到了灌水器的实验压力-流量曲线。通过对分布式CFD模拟结果和水力性能实验结果的比较,发现模拟得到的预测压力-流量曲线与水力性能实验得到的实际压力-流量曲线在50～150kPa范围内吻合得较好,在150kPa以上范围内存在一些偏差。详细分析了产生这些偏差的原因,提出了改善分布式CFD模拟的方法。     

泵站快速闸门上小拍门的水力损失特性分析

为研究泵站快速闸门上小拍门的水力损失特性,设计制作模型水泵装置,根据能量相减法,分析4种拍门孔口面积占比和5种开度角方案下拍门的水力损失特性.结果表明,拍门开度角和孔口面积与水力损失系数曲线呈非线性单调变化,水力损失系数随开度角和孔口面积的减小而增大,而流道出口Froude数对其影响较小;拍门开度角小于35°,孔口面积比小于25%时,水力损失系数急增;根据BP神经网络计算得到的水力损失系数的权重系数矩阵和阈值,可预测任意开度角和孔口面积比下的水力损失系数.     

附着空化流动下离心泵水力性能数值预测

采用改进的空化模型和算法，同时耦合黏性Reynolds-Averaged Navier-Stokes方程求解技术，对空化流动条件下离心泵的水力性能进行了数值预测研究．采用具有试验数据的拱形头部圆柱体空化绕流考核了所提出的空化模型和算法的准确性和可靠性．采用数值方法研究了不同流量系数下离心泵水力性能与空化系数之间的关系，预测了空化系数对离心泵叶轮表面附着空化气泡形状的影响．数值结果表明，在相同的流量系数下，存在着临界空化系数，在临界空化系数时离心泵的水力性能突然下降，空化系数越小，离心泵叶轮表面的附着空化空腔越大，同时造成水力性能下降的越快．研究结果证明了所提出的空化模型和算法能够应用干水力流体机械宅化流动时的性能预测。     

蜗壳截面形状对液力透平性能的影响

在液力透平中,蜗壳的水力损失大小对透平的性能起着至关重要的影响.针对国内外液力透平的研究现状以及其效率较低等问题,对一单级单吸液力透平的蜗壳截面形状进行研究,借助ANSYS软件得出液力透平在不同蜗壳截面形状下的压力场、速度场、性能曲线和水力损失.研究发现:在选择的矩形截面、梯形截面和圆形截面中,透平蜗壳截面是梯形截面时的效率最高,适合本文研究的模型;在同一流量下,流体在圆形截面蜗壳内的水力损失最小,但是在叶轮中损失最大,因此蜗壳截面是圆形的透平效率不是很高.     

转速对贯流泵装置流道水力参数影响的数值分析

为了研究贯流泵装置进出水流道水力性能受转速的影响规律,以贯流泵装置为研究对象进行全流道的数值计算,通过将能量性能数值预测结果与物理模型试验结果对比,验证了数值模拟结果的有效性。在考虑水泵与进出水流道内流相互影响条件下定量分析转速对进出水流道水力性能参数的影响规律。结果表明:(a)不同转速时进水流道水力损失比与流量系数的关系曲线变化趋势基本相同。相同转速时,随着流量系数的增大,进水流道水力效率逐渐减小,流道出口环量先减小、后增大;相同流量系数时,进水流道出口面的平均环量随转速的增加而增加。(b)不同转速时,随着流量系数的增大,出水流道进口入流涡角相对值先减小、后增大。在相同流量系数时,随着转速的增加,出水流道的静圧比逐渐增加,出水流道进口面的偏流角分布基本相同。     

集中供热空调管网水力工况计算机模拟软件的开发与应用

运用图论理论与管网内水流流动的流量平衡定律、回路压力平衡定律和阻力定律建立了集中供热空调管网水力工况电算的数学模型，给出了使用斯考德一恒斯雷试算迭代法求解管网中各管段流量的算法原理，说明了在解算过程中如何进行独立回路的选择、水泵性能曲线的拟合、热压值的计算和管道阻力特征数的计算等问题．使用目前流行的Visual Basic6．0语言为开发工具，在Windows XP平台下开发了界面友好、操作简单实用、功能强大的集中供热空调管网水力工况计算机模拟分析软件，推广应用前景良好．     

迷宫蜂窝密封泄漏特性的实验测量和数值研究

为研究蜂窝孔径、径向间隙和运行工况对迷宫蜂窝密封泄漏特性的影响,采用静止密封泄漏特性实验测量平台,测量了7种压比和5种径向间隙下迷宫蜂窝密封的泄漏量。基于数值求解三维Reynolds-averaged Navier-Stokes方程和标准k-ε湍流模型的方法,研究了迷宫蜂窝密封的泄漏特性。分析了压比(1.05～1.6)、密封间隙(0.4～1.2 mm)、转速(0～8 000 r/min)和蜂窝孔径(0.8、1.6、3.2 mm)对迷宫蜂窝密封泄漏特性的影响,并与光滑面迷宫密封进行了对比。研究表明：迷宫蜂窝密封的泄漏量随着压比的增加而近似线性增大;密封流量系数随径向间隙增大而有所降低,降低最大值为10%。在转速低于3 000 r/min时,转速对迷宫蜂窝密封的泄漏量影响很小;当转速高于3 000 r/min时,蜂窝结构能够抑制流体的周向运动使迷宫蜂窝密封在高转速时具有更优的密封性能,流量系数明显下降,转速升高到8 000 r/min时密封流量系数最多降低到0转速时的51%。迷宫蜂窝密封流量系数随蜂窝孔径增大先减小后升高,在孔径为0.6 mm与齿宽相等时流量系数最低,此时流量系数比光滑面迷...     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

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-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the