大型车用柴油机缩口燃烧室的结构特点及其对排放特性的影响

利用由AVL公司提供的FIRE软件，对重型车用柴油机缩口直喷式燃烧室内的气体流动特性进行了数值模拟计算分析。在此基础上，对不同缩口直径的燃烧室进行了喷射系统参数的优化匹配试验研究。结果表明，采用缩口直喷式燃烧室结构，可有效地组织燃烧室内的气流运动，并通过与喷射系统参数的优化匹配，在动力性和经济性基本保持不变的条件下，有效地改善柴油机的排放特性。     

浅析涡流技术与直喷式燃烧室的结构型式对柴油机排放的影响

本文阐述了涡流技术与直喷式燃烧室的结构型式对柴油机有害排放物的影响机理,提出了对活塞燃烧室各参数进行合理的优化,可有效地降低柴油机的排放指标。     

小型直喷式柴油机新型燃烧室的研究──设计、计算（1）

本文分析了小型直喷式柴油机燃烧室的结构形状对气缸内气流运动的影响。探讨了通过优化燃烧室的结构设计，用以改善小型直喷式柴油机燃烧特性的机理。并据此设计了四角形、花瓣形和四角花瓣形等三种小型直喷式柴油机的新型燃烧室。     

小型直喷式柴油机新型燃烧室的研究：——设计,计算（1）

本文分析了小型直喷式柴油机燃烧室的结构形状对气缸内气流运动的影响。探讨了通过优化燃烧室的结构设计，用以改善小型直喷式柴油机燃烧特性的机理。并据此设计了四角形、花瓣形和四角花瓣形等三种小型直喷式柴油机的新型燃烧室。     

供油系统各参数对直喷式(浅W型)高速柴油机性能的影响

本文以直喷式浅W型燃烧室R410 2型柴油机为试验样机。重点研究供油系统参数与浅W型燃烧室的最佳匹配及对柴油机性能的影响。文中还给出了试验样机的示功图、压力升高率图、放热规律图及各种燃烧特性参数。并且对示功图和放热规律做了初步的分析。     

4100增压柴油机燃油系统的试验研究

本文概括了4100增压柴油机燃油系统的研究工作,由燃油系统若干组合方案的对比试验确定最佳参数。同时也总结了喷嘴与直喷式燃烧室配合的经验。     

直喷式柴油机喷油嘴,进气涡流和燃烧室几何尺寸的匹配研究

直喷式柴油机燃烧过程的性能研究及模拟计算表明，混合气形成的发了坏将直接影响柴油机的经济性，动力性和排放指标，而影响直喷式柴油机混合气形成的主要因素有：油束动能、空气运动能量和燃烧室几何尺寸。本文将结合６１３０Ｑ型柴油机提高性能的研究，浅谈直喷式柴油机喷油嘴，进气涡流和燃烧室几何尺寸的匹配研究方法，并着重阐述前两者的匹配关系。     

直喷式燃烧室内油束的匹配

本文讨论了直喷式ω型燃烧室纵截面内油束的匹配,研究了油束夹角和燃烧室结构参数对匹配的影响,加深了对附壁卷流燃烧系统的认识。     

直喷式柴油机喷油嘴、进气涡流和燃烧室几何尺寸的匹配研究

直喷式柴油机燃烧过程的性能研究及模拟计算表明，混合气形成的好坏将直接影响柴油机的经济性、动力性和排放指标。而影响直喷式柴油机混合气形成的主要因素有：油束动能、空气运动能量和燃烧室几何尺寸。本文将结合６１３Ｑ型柴油机提高性能的研究，浅谈直喷式柴油机喷油嘴、进气涡流和燃烧室几何尺寸的匹配研究方法，并着重阐述前两者的匹配关系     

燃油喷射参数对直喷式柴油机燃烧性能与排放的影响

此项研究的目的是探讨在直喷式柴油机中,燃油喷射参数对燃烧性能和排放的影响。柴油机的循环情况和燃油喷射参数在发动机燃烧过程和排放中起了重要作用。 为了获得喷油参数对柴油机的燃烧性能与排放的影响情况,在带有副燃烧室的单缸直喷式柴油机上进行了试验。 试验结果表明,在不同燃油喷射压力和进气气流情况下,副燃烧室能降低排放和改善发动机性能。我们还发现,增加燃油喷射压力可提高气缸压力、气体温度,降低排放。     

直喷式柴油机燃烧室中喷雾的分布预测

本文介绍了三维准稳态喷雾模型。该模型是根据Dent~[1]二维平面准稳态喷雾模型,同时考虑缸内涡流和挤流的综合作用而建立的。其目的是为了预测在涡流和挤流作用下喷雾的分布。涡流和挤流强度可根据进气道稳流试验结果预测得到~[2]。本研究以高速直喷式6135柴油机为例,预测了喷雾的分布规律,将预测的喷束冲心线轨迹和可见廓线轨迹与实机的喷雾摄影作了比较,两者较为吻合,从而为研究直喷式柴油机的燃烧模型和性能提供了工具。     

直喷式增压柴油机燃烧过程可视化研究

介绍采用高速摄影技术研究直喷式增压柴油机的燃烧过程，研究工作在单缺柴油机上进行。研究结果表明，进气增压改善了上柴油机燃烧过程；促进了燃油和空气的混合，增加了燃油束向燃烧室中心的扩展区域，壁面附近燃油堆积量减小；缩短了着火延迟期，增加了扩散燃烧的比例，火焰扩展速度降低；改善了燃烧室内的燃烧条件，抑制了燃烧火焰向活塞顶部外溢。     

Flame structure of wall-impinging diesel fuel sprays injected by group-hole nozzles

This paper describes an investigation of the flame structure of wall-impinging diesel sprays injected by group-hole nozzles in a constant-volume combustion vessel at experimental conditions typical of a diesel engine. The particular emphasis was on the effect of the included angle between two orifices (0-15 deg. in current study) on the flame structure and combustion characteristics under various simulated engine load conditions. The laser absorption scattering (LAS) technique was applied to analyze the spray and mixture properties. Direct flame imaging and OH chemiluminescence imaging were utilized to quantify the ignition delay, flame geometrical parameters, and OH chemiluminescence intensity. The images show that the asymmetric flame structure emerges in wall-impinging group-hole nozzle sprays as larger included angle and higher engine load conditions are applied, which is consistent with the spray shape observed by LAS. Compared to the base nozzle, group-hole nozzles with large included angles yield higher overall OH chemiluminescence intensity, wider flame area, and greater proportion of high OH intensity, implying the better fuel/air mixing and improved combustion characteristics. The advantages of group-hole nozzle are more pronounced under high load conditions. Based on the results, the feasibility of group-hole nozzle for practical direct injection diesel engines is also discussed. It is concluded that the asymmetric flame structure of a group-hole nozzle spray is favorable to reduce soot formation over wide engine loads. However, the hole configuration of the group-hole nozzle should be carefully considered so as to achieve proper air utilization in the combustion chamber. Stoichiometric diesel combustion is another promising application of group-hole nozzle.     

Improvement of fuel economy of an indirect injection (IDI) diesel engine with two-stage injection

This paper focuses on the effects of early stage injection and two-stage injection on the combustion characteristics and engine performances of an indirect injection (IDI) diesel engine. In a direct injection (DI) diesel engine, HC emission increases with early stage injection because some of the fuel spray adheres to the cylinder wall and burns in the gap between the piston and the cylinder. On the other hand, since the fuel spray of early stage injection in an IDI diesel engine is injected into an auxiliary combustion chamber such as a swirl chamber, the IDI diesel engine could reduced the HC emission produced from the gap compared with a DI diesel engine. In a two-stage injection IDI diesel engine, NO and smoke emissions are improved when the amount of fuel in the first stage injection is small and the first stage injection timing is advanced over −80° TDC. And 20% improvement in fuel consumption is achieved when the first stage injection timing is advanced over −80° TDC. Conversely, HC and CO emissions of two-stage injection increases compared with that of conventional injection of an IDI diesel engine. However, CO emission can be improved a little when the first stage injection timing is advanced over −100° TDC and the second stage injection timing is retarded over TDC.     

基于响应面近似模型的双层喷孔参数优化研究

在共轨柴油机上采用双层交错布置喷孔油嘴可以改善柴油机的经济性和排放性能。针对双层交错布置喷孔油嘴与燃烧室优化匹配问题,采用CFD软件,运用中心组合试验设计方法设计燃油系统参数的试验计算矩阵并进行数值计算;再以响应面近似模型构造燃烧和排放的优化目标函数;最后运用多岛遗传算法对该近似模型进行全局寻优,确定燃油系统参数的优化组合,并在试验台架上进行了优化方案的配机试验。结果表明:小的喷孔直径、较多的喷孔以及适当的上下层喷孔喷射夹角可提高油束的雾化质量。     

柴油机多维燃烧模拟程序及其参数灵敏性研究

在一个模拟直喷式柴油机燃烧过程的二维模型的基础上,开发了可在微机上运行的二维计算程序,程序名为ＲＥＳＤ－２Ｄ。程序中采用了亚网格尺度（ＳＧＳ）湍流模型、蒸发性液体射流喷雾模型、着火延迟期模型,燃烧和排放的计算采用部分平衡流方法。随后对该模拟程序中与计算参数、燃油喷射、混合、燃烧等相关参数的灵敏性进行了研究,所得到的结论对于ＲＥＳＤ－２Ｄ程序走向实用化有指导意义。还应用该程序针对１２１５０Ｌ柴油机进行了计算,给出了计算结果     

Impact of alternative fuel properties on fuel spray behavior and atomization

In order to verify and solve the problem of NOx and PM emissions, it is necessary to directly observe the internal combustion chamber of a diesel engine. Many studies have been performed in recent years to verify the macroscopic and microscopic behavior of the injected fuel spray because observing it is not easy due to the difficulties of the experiment. Researchers have investigated the spray characteristics for various diesel injector nozzles over a wide range of temperatures and pressure, but there is lack of evaluation for the spray characteristics for biodiesel. At a time when rapid rise of fuel prices and depleting hydrocarbon resources of the world have forced us to look for alternative fuels biodiesel produced by transesterification of non-edible vegetable oils is promising to be an important additive/substitute to petro diesel. Biodiesel being an oxygenated and sulfur-free fuel leads to more complete combustion and lower emissions. But, the energy content or net calorific value of biodiesel is less than that of diesel fuel; also it has higher viscosity and density, than diesel fuel. A considerable improvement in these properties can be obtained by mixing diesel and biodiesel and then using the blends. Biodiesel and biodiesel/petro diesel blends, with their higher lubricity levels, are increasingly being utilized as an alternative. Present paper analyzed the correlation of injection parameters that will affect the spray characteristics of biodiesel. Observations for analyzing the effect of injection parameters on spray cone angle, break up length and fuel penetration were made. Finally the performance and emissions tests were studied. Atomization and vaporization of fuel are greatly influenced by viscosity and density of fuel and these properties are temperature dependent. Thus fuel inlet temperature plays a very important role in fuel atomization process. At higher temperature viscosity of fuel decreases which enhances the atomization of biofuels.