大功率柴油机电控燃油喷射系统的仿真研究

通过对从美国引进的大功率柴油机电控单体泵燃油喷射系统喷油泵、喷油器的实体测绘。得到了燃油系统的结构参数．利用仿真软件建立了引进大功率柴油机燃油系统的仿真模型。得出的性能曲线与国产大功率柴油机燃油系统进行了对比,分析其优势,为后续优化和改进国产柴油机燃油喷射系统奠定基础．     

喷油嘴喷注雾化结构及机理探讨

根据近代实验的有关成果，对柴油机喷油嘴喷注雾化结构的形成和发展过程作了简要的 这，并对高压燃油的主要参数与喷射环境的关系作了较详细的分析。提出了分区域，分阶段分析雾化机理的物理模型，并对传统的以油膜振盈为基础的模型，作了一些新的补充和解释。     

二冲程气道喷射式液压自由活塞发动机喷射方式分析及优化仿真

为降低二冲程液压自由活塞发动机(hydraulic free piston engine, HFPE)使用气道喷射方式时的燃油消耗,将喷油器置于气道内扫气口处,使用CONVERGE软件建立了从燃油喷射过程到混合气生成过程的三维计算流体动力学仿真模型,研究了燃油喷射相位、喷射角度以及喷油器流量大小对混合气生成过程的影响。结果表明:燃油喷射角度越小、喷射相位越晚,燃油捕集率越高,最高可达99%,比新鲜空气捕获率高出39%,燃油消耗率降低较大;燃油喷射角度过大或过小,都会恶化燃油的气化效果,最佳的燃油喷射角度(与缸头法线方向夹角为43°～48°)可以获得最高的燃油气化率,但较早的喷射相位会使油束在缸内的实际流动方向发生改变,增加缸壁油膜的生成量,降低燃油气化率;大流量的喷油器在最佳的喷射角度上拥有更好的燃油捕集和气化效果,同时对应效果较好的喷射相位区间宽度大于小流量喷油器,喷射灵活性更佳。     

柴油机喷油嘴内燃油流动三维数值模拟

喷油嘴内的流动状态以及燃油喷射情况在很大程度上影响柴油机的排放和经济性能。鉴于试验和测量受种种条件的限制,可利用CFD软件AVL-FIRE中的混合多相流模型加空穴模型,通过数值计算,模拟了柴油机孔式喷油嘴内的燃油流动状态。模拟出喷油嘴内燃油流动状况,空穴的产生、发展及分布情况。进一步分析了不同燃油喷射压力对喷孔内空穴分布的影响。分析表明,通过本方法可预测喷油嘴内的燃油流动状况,可为喷油嘴设计的合理性指出改进方向。     

面向控制的船用高压共轨系统实时仿真模型开发

为给船用柴油机电控系统软件提供受控对象,本文以船用柴油机高压共轨燃油系统作为仿真对象,建立高压共轨燃油系统的性能仿真模型,计算得到共轨各部件的特性数据,再利用性能仿真计算数据和计算公式建立实时仿真模型,实时仿真模型包括高压油泵子模型、共轨管子模型、喷油器子模型和质量转换子模型等.实时仿真模型可根据电控系统发出的燃油喷射...     

常温下直流式燃油喷嘴的斜喷实验研究及计算喷嘴后方浓度场的线源方法

本文通过对常温、常压下直流式喷嘴在不同喷射方向、气流速度、供油压差、喷嘴孔径及下游距离等条件下的实验研究,提出了线形扩散源的模型,即把喷嘴喷射轴线上的一段细油柱视为流场中油雾流的扩散源,并据此导出了常温下计算喷嘴下游燃油浓度分布的线源公式。公式中的有关系数均由实验结果整理得出。计算表明,误差一般在±15％之内,说明此公式能在所实验的参数范围内,预估外函加力空中直流式喷嘴侧喷或斜喷时的燃油浓度分布。     

F912Q柴油机喷油、燃烧、排放的多维仿真研究

利用KIVA-3V程序对F912Q风冷、直喷柴油机进行了仿真研究.仿真计算采用三维网络结构,计算区域包括进气道、进气阀、气缸、排气阀、排气道.仿真计算得到的缸内压力-时间曲线和排气污染物各成份分别与试验数据进行了对比,结果表明仿真计算可以较好地再现实际的发动机工作过程.在此基础上,利用KIVA-3V程序研究了涡流强度以及喷雾锥角对燃油喷射、蒸发和油气混合过程的影响.仿真结果表明:通过适当加大涡流比可以显著促进燃油蒸发和油气混合过程;喷雾锥角对发动机蒸发和燃烧过程有显著的影响,存在一个最佳的喷雾锥角使上述过程达到最优.     

电控喷油器动态过程模拟分析

在喷油器的喷射过程中，为了更好地了解影响其快速开启和关闭的因素，可对喷油器的动态喷射过程进行模拟，将整个喷射过程分为6个阶段，并对每个阶段进行了较为详细的分析，从理论上建立了一套计算模型。通过该模型建立的驱动电路电流特性曲线和芯管组件升程特性曲线与试验测得的曲线吻合较好。利用这套模型可以更好地了解影响喷射过程的电磁参数和结构参数，为电控喷油器的开发提供了一定的理论依据。     

燃油分层喷射发动机燃油系统的故障诊断

介绍了燃油分层喷射发动机的技术特点,阐述了燃油分层喷射发动机与进气道喷射发动机在燃油系统组成和工作原理方面的区别,分析了燃油系统故障产生的原因,并提出了诊断方法。     

涡流室式柴油机燃油雾化过程的三维数值模拟

将喷射燃油分为液核区和气液混合区,用Ｋ－Ｈ不稳定性理论和Ｒ－Ｔ不稳定性理论来分别描述其油滴破碎过程,并考虑油滴间的碰撞与聚合,建立了燃油雾化模型将此模型应用到涡流室式柴油机中,进行三维数值模拟计算,得到了涡流室式柴油机油滴雾化过程的一些规律,取得了与高速摄影照片相一致的结果     

二甲醚柴油缸内温度场数值模拟研究

在K IVA源程序中向燃料库添加液态DME的各种物性参数数据模块,建立二甲醚燃料库,针对二甲醚燃料建立油束模型和燃烧模型,并把这些数学模型耦合入K IVA后形成子程序,并建立二甲醚燃烧数值仿真计算平台.利用建立的平台计算二甲醚柴油缸内燃烧温度场.得出:仿真结果与试验结果相同,所建立的二甲醚燃烧过程数值模拟平台是有一定的实用性.研究结果表明:燃用二甲醚的发动机相对于燃用柴油的发动机的燃烧时刻相对提前,对应不同时刻的二甲醚发动机缸内最高温度均小于柴油发动机,且高温分布范围较小,这将抑制NOx的生成.     

柴油机喷雾碰壁现象的闪光摄影法研究

本文应用闪光摄影法，在压力容顺内研究了柴油机喷雾碰壁现象。试验结果表明，碰壁喷雾呈圆盘状，其扩散范围受启喷压力、喷油背压等因素的影响。     

水喷雾消防系统在高层建筑内燃油设备房中的应用

提出了水喷雾系统用于高层建筑燃油设备房消防的新思路,对系统设计方法、设计参数的选择进行了阐述,并提出了喷雾喷头优化选择的方法。通过工程实例与卤代烷系统的比较,论证了水喷雾系统用于高层建筑燃油设备房的可行性和经济性。     

An experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry

This paper presents an experimental study on the spray characteristics of diesel-dimethyl ether (DME) blended fuels by phase doppler anemometry (PDA). Blended fuels with DME mass fractions of 15%, 30% and pure diesel fuel were used to evaluate the effect of the DME concentration on the spray pattern, droplet size and velocity. The data for spray velocity vector and droplet size field were obtained. The experimental results reveal that the micro-explosive function exists in the jet of diesel-dimethyl ether (DME) blended fuels and the radial velocity of the blended fuels spray is larger than that of conventional diesel fuel spray near the nozzle exit. At the downstream part of the spray, the radial velocity and its attenuation rate of blended fuels are much more uniform and smaller than those of pure diesel spray. At the centerline of the spray, the attenuation rates of all spray axial velocities are similar. With the increase of DME concentration in the fuel, the spray angle and the exit velocity increase and the droplet size deceases. Supported by the National Natural Science Foundation of China (Grant No. 50806046) and the National Basic Research Program of China (“973” Project) (Grant No. 2007CB210007)     

内混式空气雾化喷嘴的研究

对内混式空气雾化喷嘴的雾化特性进行了实验研究,得到了有关几何结构尺寸对雾化细度MMD的关系曲线和数据,得出了此类喷嘴的一些有意义的雾化规律,为此种喷嘴应用于表面改性设备中,并用于超细颗粒雾化提供了有价值的实验依据和方法。     

Spray Characteristics of Air-Assisted Injector Under Different Ambient Pressures

Spray atomization of liquid fuel plays an important role in droplet evaporation, combustible mixture formation and subsequent combustion process. Well-atomized liquid spray contributes to high fuel efficiency and low pollutant emissions. Gasoline direct injection(GDI) has been recognized as one of the most effective ways to improve fuel atomization. As a special direct injection method, the air-assisted direct injection utilizes high-speed flow of high-pressure air at the injector exit to assist liquid fuel injection and promote spray atomization at a low injection pressure. This injection method has excellent application potential and advantages for high performance and lightweight engines. In this study, the hollow cone spray emerging from an air-assisted injector was studied in a constant volume chamber with the ambient pressures ranging from 5 kPa to 300 kPa. External macro characteristics of spray were obtained using high speed backlit imaging. Phase Doppler particle analyzer(PDPA) was utilized to study the microcosmic spray characteristics. The results show that under the flash boiling condition, the spray will generate a strong flash boiling point which causes the cone shape spray to expand both inwards and outwards. The axisymmetric inward expansion would converge together and form a lathy aggregation area below the nozzle and the axisymmetric outward expansion greatly increases the spray width. The sauter mean diameter (SMD) of flash boiling condition can be reduced to 5 μm compared to the level close to 10 μm in the non-flash boiling condition.     

伞型喷油器在挤流口燃烧室的应用研究

本文提出了一种令型喷油器和挤流口燃烧室组成的燃烧系统，并在１１０单缸试验机上进行了试验研究。试验证实了这种燃烧系统在降低柴油机的燃油消耗，改善烟度、排放等方面具有优越性。     

伞喷燃烧系统的应用研究

本文绘出了伞喷燃烧方式在１３５型试验机上进行的试验研究，性能参数表明该燃烧方式具有热预混合燃烧的特点，且改善了经济性、工作粗暴性和排入指标。     

The measurement of internal surface characteristics of fuel nozzle orifices using the synchrotron X-ray micro CT technology

The design of fuel nozzle orifices at micrometer scales is crucial for generating desired fuel spray patterns, and consequently optimizing fuel combustion and emission in internal combustion engines. Although there have been several recent advancements in the characterization of orifice internal geometries, quantitative studies on the orifice internal wall surface characteristics are still challeges due to the lack of effective measuring methods. A new method for quantifying the internal wall surface characteristics of fuel nozzle micro-orifices is presented in this study to achieve a better understanding and prediction of spray characteristics: Firstly, by using the synchrotron X-ray micro CT technology, a three-dimensional digital model of the fuel nozzle tip was constructed. Secondly, a data post-processing technique was then applied to unfold the orifice internal wall surface to a flat base plane. Finally, the conventional surface characteristic quantification techniques can be used to evaluate the wall surface characteristics. Two diesel nozzles with identical orifice geometry design but different hydraulic grinding time were measured using this method. One nozzle was hydro-ground for 2 s while the other was not. The internal wall surfaces of the two orifices were successfully unfolded to base planes and their surface characteristics were respectively analyzed. The surface fluctuation data were perfectly reproduced by a Gaussian distribution function. The standard deviations of the distribution demonstrate the fluctuation range and the distribution of the entire surface fluctuation profiles. As an effective parameter to evaluate the hydraulic grinding process and the spray behaviors, the standard deviation was considered feasible for the analysis of the orifice internal wall surface characteristics.     

柴油机燃烧过程模拟分析

为了解柴油机燃烧的微观情况,利用商用计算软件STAR-CD对增压中冷柴油机进行了燃烧模拟分析。在试验台架上调整供油提前角,针对烟度及NOx排放性能进行了试验,为模拟计算获取了温度、压力等初始条件。对试验工况进行了燃烧模拟,结果表明,喷油过程会形成喷注头部,在喷油后期喷注尾部又从喷注整体上脱落;未来得及燃烧的燃油撞壁后,其小部分向上运动逐渐进入余隙狭缝之中,大部分向下沿ω形壁面形成滚流运动;着火首先发生在油束外缘区域,并且随着燃烧的进行,高温区一直出现在燃油蒸汽的外层。