二甲醚发动机低压共轨系统轨压特性研究

以二甲醚发动机燃油系统为研究对象,建立发动机低压共轨系统的仿真模型,分析影响共轨管压力建立时间和压力波动的主要因素,并探讨了共轨管内的燃油压力特性。结果表明,共轨管的容积、内径、长度、长径比、油泵供油压力对共轨压力特性的影响较大,合理地选择共轨管尺寸和供油压力,既能维持共轨压力的稳定,也能保持较短的压力响应时间。     

电控高压共轨喷油系统结构参数对轨内压力波动仿真分析

采用GT软件建立电控高压共轨燃油喷射系统模型,并利用构建的仿真模型研究高压油泵的进油阀组件、排油阀组件以及活塞凸轮组件,其三个主要部分的结构参数变化对共轨管中压力波动的影响。通过研究可知高压泵在实际工作时所承受的压力波与活塞的状态有直接关系,且活塞状态包括其质量、长度、直径、容积等。为了更好地研究进排油阀对压力波动之间的关系,选用8组参数进行实验研究并验证进排油阀体直径、质量、弹簧预紧力、弹簧刚度的变化与压力波动之间的相互影响作用,进而通过对比选取最佳阀体。通过仿真分析可知,共轨喷油系统压力波动程度会受到系统结构参数的影响,并可以为系统的优化设计提供参考依据。     

4JB1柴油机高压喷射系统选型及管路匹配

采用FSEM(fuel system evaluation method)的方法进行柴油机高压喷射系统选型,针对4JB1柴油机选择BOSCH公司的第2代共轨系统.利用AMESim建立高压共轨柴油机供油系统模型,包括高压供油泵子模型、压力调节阀子模型、喷油器子模型和连接它们的高压油管子模型.仿真研究共轨管容积、高压油管长度和内径等参数对共轨管中的压力建立和压力波动的影响,并针对4JB1共轨柴油机进行共轨系统管路参数选择和试验验证,结果表明匹配的管路系统满足共轨柴油机轨压快响应和小波动的要求.     

电控喷射系统喷油器压力波动仿真分析

利用仿真软件GT-Suite建立了电控共轨式燃油喷射系统仿真模型,通过实验验证了仿真模型的准确性并且进行了简单对比分析。通过改变共轨式喷油器结构参数,即喷孔数量、进油节流孔直径以及针阀质量进行仿真计算。利用仿真结果分析,探讨喷油器结构参数对共轨喷油系统压力波动的影响,为共轨喷油器的优化设计提供有效依据。     

高压共轨喷油器响应特性的仿真分析

为了分析高压共轨喷油器结构参数的变化对喷油器响应特性的影响,以某型号重型柴油机高压共轨喷油器为研究对象,通过AMESim软件建立喷油器仿真模型,进行试验验证模型准确性.结果表明:进油孔孔径增大会提升开启响应速度但降低喷油器的关闭响应速度,出油孔孔径的增大提高喷油器的开启响应速度;控制柱塞直径的增大会提升喷油器的关闭响应速度但降低喷油器的开启响应速度;针阀密封直径的增大会同时提高开启和关闭响应速度;针阀弹簧预紧力的增加会带来针阀开启时间的延长和关闭时间的缩短.因此喷油器设计开发过程中应合理选取进油孔径取值并适当增大出油孔径及针阀密封直径.为高压共轨喷油器结构参数的优化设计提供参考.     

柴油机共轨管与高压油管结构参数对系统的影响

基于两位两通电磁阀的高压共轨燃油喷射系统模型的仿真过程,利用AVL公司开发的HYDSIM软件建立模型,给出共轨管与高压油管参数对喷射过程的影响.为喷油系统的优化设计和试验台验证提供理论依据.     

共轨高压柴油泵的紧密性测试方法

传统油泵生产中的功能性测试已无法满足共轨高压柴油泵的紧密性要求,因此,在共轨高压柴油泵生产中应建立先进行功能性测试再进行紧密性测试的系统.为了验证该测试系统的有效性,采用激光焊接仪在泵的吸油阀座上焊接颗粒,模拟油泵中常见的颗粒故障,测试不同颗粒影响下油泵的紧密性.试验结果表明,最小焊接颗粒(13μm)的油泵虽然通过功能性测试,但未能通过紧密性测试.该测试系统可提高检测油泵紧密性的能力,并已成功应用于柴油泵的生产中.     

电控柴油机共轨管进出油口位置对喷油压力波动的影响

现代电控柴油机共轨内压力的瞬态波动会直接影响到燃油喷射系统喷油量的均衡.采用AVL公司的workspace 4.0软件建立了燃油喷射系统模型,设定不同进出油口的连接方式,分析了电控柴油机共轨管进油口在不同位置时对喷射压力波动产生的影响.     

基于流量特性的共轨系统前馈式压力控制策略研究

研究高压共轨柴油机关键部件对共轨压力的影响和极端工况下共轨压力的控制.分析高压共轨系统的油泵流量特性、燃油泄漏量和电磁阀特性等对共轨压力的影响,采用前馈式控制策略通过调节出油阀流量实现轨压的控制.实验结果表明,该方法对于不同类型的电磁阀具有很好的适应性,针对喷油量变化很大的工况能提前做出反应,实现快速、稳定和准确地控制压力.     

柱塞副温度场数学建模与性能分析

为完善轴向柱塞泵柱塞副性能分析理论体系,针对温度分布影响柱塞副性能问题进行研究,建立瞬时油膜厚度场、压力场和温度场模型以及柱塞副摩擦与泄漏模型,采用交错网格技术划分油膜网格,采用有限体积法求解能量方程和雷诺方程,以MATLAB仿真软件为依托耦合各物理场模型和柱塞微运动特性,对柱塞副动态温度场进行数值求解。研究温度对油膜压力分布、柱塞副轴向摩擦力和泄漏量的影响,并分析油膜不同入口温度对柱塞副性能参数的影响规律。研究结果表明:温度变化数值计算结果与实验结果基本一致;在柱塞副中引入动态温度后油膜压力峰值明显降低,轴向摩擦力有所下降,但柱塞副泄漏量增加较快;控制油膜入口油温能有效提高柱塞副工作性能。     

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.     

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     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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