利用废气滞留改善缸内直喷汽油机部分负荷性能的研究

废气滞留比传统的废气再循环具有更好的稀释和加热混合气作用,有利于减小汽油机中小负荷泵气损失,降低油耗.在一台缸内直喷汽油机(GDI)上对比研究了部分负荷下利用负阀重叠(NVO)产生废气滞留对于发动机性能的影响.结果表明,利用废气滞留方法可使发动机油耗降低5%～16%,并且随着负荷减小节油效果明显.分析表明,废气滞留可以提高进气歧管压力,明显降低泵气损失;混合气温度提高促进燃烧更完全,使燃烧效率得以提高;但燃烧速度会有一定程度降低,循环波动有所增大;综合作用下使得有效热效率提高.同时,废气滞留作用可降低缸内直喷汽油机HC、CO排放,尤其可显著降低NOx排放达70%以上.     

可视化卫星测试交互软件的设计及应用

航天工程和信息技术是当今两大蓬勃发展的产业,将现代计算机可视化技术完美地融入到卫星综合测试之中,必将大幅度提高测试的质量和效率。根据对卫星测试可视化的总体构想,引入计算机可视化的关键技术,并将其与卫星地面综合测试技术深入结合。利用完整的实例,详细介绍了可视化卫星综合测试的实现并给出了远景展望。     

基于C# GDI＋的雷达航线绘制软件的设计与实现

为了提高雷达操纵员训练效果,解决手工绘制航线曲线不平滑、校点不精确等问题,采用拉格朗日插值算法,使记录的坐标点数组按插值的方式进行均匀化,提高校点精度;通过对话框方式和两种显示模式,简化了航线合批处理与航线绘制的复杂度;调用C# GDI＋中的绘制函数绘制航线,保证航线平滑,提高雷达航线制作的效率。     

基于GDI+技术的电力系统图形软件的设计与应用

应用GDI＋技术,在微软公司提供的Visual Basic．NET2005平台上开发电力系统图形化应用程序．对GDI＋技术作了简要的介绍,对电力系统元件的定义,图形信息的录人与保存作了描述,并在此基础上进行程序编写．对电力系统图形化程序的编写具有一定的指导意思．     

基于VC++.NET的参数化CAI系统设计

本文结合VC++.NET的GDI+托管类的定义,研究了参数化CAI系统设计的原理和方法,并给出了一个参数化CAI系统设计的实例。     

缸内直喷汽油机起动控制

在缸内直喷增压汽油机上,运用自主开发的直喷发动机控制软硬件系统,研究了喷油脉宽、点火提前角和起动过程PID控制器参数对发动机起动的影响。试验结果表明：喷油脉宽为45℃A,发动机起动转速波动小。点火提前角为12℃A时,发动机起动转矩最大。PID控制的KP=1时,转速响应迅速;KI=0.2时,实现无误差跟踪转速,超调量小;...     

Atomization characteristics and prediction accuracy of LISA-DDB model for gasoline direct injection spray

In this paper, the spray atomization characteristics of a gasoline direct-injection injector were investigated experimentally and numerically. To visualize the developing spray process, a laser sheet method with a Nd :YAG laser was utilized. The microscopic atomization characteristics such as the droplet size and velocity distribution were also obtained by using a phase Doppler particle analyzer system at the 5 MPa of injection pressure. With the experiments, the calculations of spray atomization were conducted by using the KIVA code with the LISA-DDB breakup model. Based on the agreement with the experimental results, the prediction accuracy of LISA-DDB breakup model was investigated in terms of the spray shapes, spray tip penetration, SMD distribution, and axial mean velocity. The results of this study provides the macroscopic and microscopic characteristics of the spray atomization, and prediction accuracy of the LISA-DDB model.     

汽油机缸内直喷技术的研究与发展

围绕汽油机的节能和排放问题,本文主要从结构和进气组织等方面,概述了被称为第三种燃烧方式的汽油缸内直喷(GDI)的发展和研究。     

金属型GPF对GDI发动机颗粒物微观特性的影响

采用高分辨透射电镜(HRTEM)对安装了金属型汽油机颗粒捕集器(GPF)的汽油缸内直喷(GDI)发动机颗粒物进行观察,研究了转速为1500 r/min,负荷分别为25％、50％、75％和100％工况下的GPF前、后端颗粒物微观形貌及微观结构参数变化.结果表明:组成颗粒物的基本粒子均呈近似球形,堆积形成链状、枝状和环状等...     

Fuel injector deposits in direct-injection spark-ignition engines

Controlling fuel injector deposits is recognized as a challenge for advanced direct-injection spark-ignition (DISI) engines. This paper gives a comprehensive overview of the research on formation, measurement, effect, and mitigation of injector deposits in DISI engines. Methodologies for the injector deposit studies include visual and compositional analysis. It is shown that injector deposits will reduce injector fuel flow rates, and lead to changes in spray characteristics. Consequently, spray angle and envelope are likely to be affected, and spray penetration distance as well as droplet diameter can be increased. Injector deposits are revealed to be primarily fuel-derived and created by two distinct free radical pathways, i.e., low temperature auto-oxidation and high temperature pyrolysis. Fuel compositions (olefins, aromatics, and sulphur), as well as T90 parameter, are significant factors in injector deposit formation. The worst consequences of injector fouling are pre-ignition, and engine misfiring and malfunction. Emissions, especially particulates, dramatically increase as the fuel injector becomes fouled. It appears that fuel detergent is the most effective method in controlling injector deposit formation if its chemistry and dosage rate are optimized. Outward opening piezo-driven injector configuration with a good surface finish, a sharp nozzle inlet, and a counter bore design, is useful in preventing injector deposit formation. Reducing injector nozzle temperature by methods such as designing special injector cooling passages, and improving engine design are also proven to be helpful in reducing injector fouling. Anti-deposit coatings only delay the onset of injector deposit formation.