车用多缸直喷柴油机燃用二甲醚的燃烧和排放特性研究

开展了4缸直喷柴油机燃用二甲醚时的燃烧和排放特性的研究。结果表明，适当增加喷油器伸出缸盖底平面的距离，采用流通截面较大的喷油器，降低启喷压力，可以提高CA498发动机燃用二甲醚时的热效率。燃用二甲醚时，发动机缸内的最大爆发压力和压力升高率低于燃用柴油时的情况。二甲醚发动机在所有工况下均可实现无碳烟排放，NO，排放约为柴油机的50％，CO和HC排放与柴油机相当。试验结果表明二甲醚是一种高效、低排放、燃烧噪声低的柴油机新型代用燃料。     

双弹簧喷油器改善柴油机噪声的试验研究

通过对双弹簧喷油器及单弹簧喷油器在CA6110ZLRA5型柴油机上进行有关性能和噪声的试验研究，结果表明：使用双弹簧喷油器能在保持柴油机动力性，经济性的前提下，明显地改善NOx排放以及降低柴油机噪声（燃烧噪声），特别在柴油机中，低速和中，低负荷下效果更显著，使用双弹簧喷油器后喷油规律和放热规律的变化为以上结果提供了依据。     

柴油机采用轻量针阀喷油器的节油研究

研究了柴油机喷油器采用轻量针阀后，由于针阀质量减轻，提高了针阀的开启速度和落座速度，减小了喷油持续角，而且燃油喷注的油滴平均直径减小，燃烧改善，从而获得明显的节油效果。     

燃油撞击对柴油机混合气形成及其燃烧过程影响的研究

介绍了具有油束撞击效应的轴针式喷油器在不同柴油机燃烧系统中的应用。试验结果表明,当这种喷油器运用于涡流室式柴油机时,可以起到降低发动机燃油消耗与排气烟度的作用;运用到直喷式燃烧系统时,发动机的运转正常,起动方便,但目前还存在燃油消耗率和排气烟度高的不足。此外,还详细介绍了这种轴针式喷油嘴产生的不同形式的碰撞效果对直喷式发动机性能影响的研究结果。     

生物油/柴油乳化燃料用于柴油机的试验研究

为研究生物油/柴油乳化燃料作为柴油机燃料的性能,通过添加适量乳化剂配制成乳化燃料并在柴油机上燃用,分析了乳化燃料的燃烧特性、经济性、排放特性及对柴油机的影响.结果表明:生物油与柴油可以通过乳化形成较稳定的乳化燃料且可将其用于柴油机,但燃油消耗率比柴油高,热效率比单一柴油低;CH和CO排放增加,NO_x排放降低;使用一段时间后,供油管路中的橡胶密封件出现溶胀效应,排放因喷油器被磨蚀而随时间呈非正常变化.试验对进一步研究生物油在柴油机上的应用具有重要意义.     

用双弹簧喷油器降低直喷式柴油机燃烧噪声的研究

本文阐述利用双弹簧喷油器来降低１３５系列直喷式柴油机燃烧噪声，研究观察了双弹簧喷油器的喷油规律和工作过程，这有助于更好地了解双弹簧喷油器降低燃烧噪声的规律特性。通过长管法测出双弹簧喷油器的喷油规律，从喷油规律图上能清晰可见：第一级开启压力的变化对燃油喷射初期的喷油率影响不大，第二级开启压力变化时，初期喷油率形状有所变化，而预升程即第一级升程的改变则很大程度上影响初期喷油率的形状。通过大量试验得出：双弹簧喷油器的降噪效果在中低速范围内最明显，随着柴油机转速的升高，其降噪效果下降。高速时燃烧噪声显著增加，但对涡轮增压柴油机，由于高速时滞燃期短，则可不受这种规律的限制。     

生物柴油的排放试验研究

通过对燃烧生物柴油发动机排放污染物的测量和分析,探讨了生物柴油降低柴油机排气污染物的机理。分析了不同配比的生物柴油燃烧污染物随发动机转速、负荷的变化规律,得到了生物柴油的最佳配比方案。研究结果表明:生物柴油可以有效地降低柴油机的排气污染物,尤其是颗粒污染物;随着生物燃料中油酸甲脂含量的增加,柴油机的各种排气污染物均有不同幅度的降低。     

柴油机燃用F-T柴油与0号柴油混合燃料的燃烧特性

根据实测的喷油器针阀升程和示功图,开展了直喷式柴油机燃用F-T柴油与0号柴油混合燃料时燃烧特性的研究．试验用燃料为0号柴油、含25%和50%F-T柴油的混合燃料以及100%F-T柴油．结果表明,在相同工况下,随着混合燃料中F-T柴油比例的增加,喷油延迟角增大,而喷油持续期变化不大．滞燃期随着F-T柴油比例的增加而缩短,其中当F-T柴油的比例由0增至25%时,滞燃期缩短最为明显,此后进一步增加F-T柴油的比例,滞燃期缩短幅度减小．随着混合燃料中F-T柴油比例的增加,预混燃烧放热峰值降低,扩散燃烧放热峰值增大,燃烧持续期略有延长,缸内最高燃烧压力和气体最高平均温度降低,最大压力升高率显著下降,发动机的燃烧噪音和机械损失减小,有效燃油消耗率和有效热效率得到改善．     

P系列双弹簧喷油器与CA498柴油机的匹配研究

在一台498增压中冷柴油机上对开发的P系列双弹簧喷油器与普通P系列单弹簧喷油器进行了性能、排放、噪声及低速稳定性等一系列匹配试验研究,结果表明：使用P系列双弹簧喷油器能在保持柴油机动力性、经济性原有较好水平的前提下,明显地改善低速稳定性、NOx排放以及降低柴油机噪声(燃烧噪声)。     

采用含氧燃料和EGR同时降低直喷式柴油机碳烟和NOx排放的试验研究

在一台TY1100轻型直喷式柴油机上，研究了碳酸二甲酯（DMC）作为含氧燃料添加剂对柴油机烟度和性能的影响。结果表明，在发动机燃油和燃烧系统不作变动的条件下，随着DMC在柴油中添加比例的增加，排气烟度逐步下降，热效率提高。当添加比例在10％-15％时，烟度降低40％-50％，热效率增加了6.9％，发动机功率基本不变。添加碳酸二甲酯并采用EGR可以同时降低碳烟和NOx。研究表明，柴油中添加15％DMC，在12％左右的EGR下，与原机比较，烟度降低了35％，NOx排放降低了33％。混合燃料的放热规律与纯柴油相比差异不大，但预混燃烧量增加，扩散燃烧速率快，发动机最高燃烧压力、温度和压力升高率偏高。     

对柴油机用轴针式喷油器实现直喷燃烧的分析

从研究Elsbett“双热区”隔热直喷燃烧系统（DuothermicCombustionSystem）出发,分析了喷雾贯穿。喷孔直径、喷油器安装位置、铰接式铸铁活塞、采用机油冷却及增压等对混合气形成及燃烧过程的影响。认为,适当增加进气涡流强度、缩小喷孔与轴针之间的配合公差、采用铸铁活塞头部、以机油作为冷却介质、实现高温冷却等措施,有利于改善小缸径柴油机混合气形成及燃烧过程。“双热区”燃烧系统对采用轴针式喷嘴实现小缸径柴油机的直喷燃烧有许多值得借鉴之处。     

喷油策略对伞喷柴油机工作过程影响的数值模拟研究

对一种新型柴油机喷嘴进行了可视化试验与模拟计算.应用三维CFD（Computational Fluid Dynamic）软件模拟了两种喷雾形式下不同喷油参数对柴油机混合气形成、燃烧及排放的影响,得到了最佳的喷油策略.结果表明,相对于复合喷雾,伞形喷雾在混合气形成方面存在一定的优势,对燃烧和排放有较大改善;混和气形成较好,燃烧效率高,指示油耗较低,碳烟二次氧化迅速.并且伞形喷雾中,采用小的索特平均直径,高的喷射速度,能够使发动机性能得到较大地改善.     

A review on deposit formation in the injector of diesel engines running on biodiesel

For the short-term use of diesel engines, biodiesel can provide a comparable engine performance to that of using fossil diesel fuel. However, some arising problems including the reduction of the engine performance, the increase in lacquer deposits, and excessive carbon blacks in the combustion chamber and in the injectors resulting in an increase in the emissions and the damage to the engine have been indicated. Deposits formed inside or outside the injector may have an adverse influence on the engine performance and the fuel injection system. In this study, a review of the formed deposits in the injector of diesel engines fueled with biodiesel was conducted. The physicochemical mechanism of the deposit formation in the injector including injector nozzles, injector holes, and injector tips was mentioned. Moreover, the test-cycles for determining the deposit formation level in the injector were also introduced. Especially, the effects of the key factors such as biodiesel components, temperature, and injector configurations on the formation level of deposits were reviewed, and the utilization of the cativation mechanism in the controlling strategy of the deposits was presented. Besides, the impacts of deposits in the injector on the spray characteristics, combustion, and diesel engine operation process were also referred.     

伞状喷雾及HL喷雾在柴油机均质预混合燃烧中的应用研究

针对柴油机均质预混合燃烧的混合气形成提出满足喷雾碰壁少，雾化好等要求的早期喷射缸内预混合方式，并对喷雾状态、性质及其预混合燃烧做了深入探讨。对HL喷雾与多孔喷雾做了比较研究。试验证明，HL喷雾具备双工作模式的能力。     

Investigation of the effect of pilot burner on lean blow out performance of a staged injector

The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real engine.
In this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test section.The experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.     

Current status of droplet and liquid combustion

The present understanding of spray combustion in rocket engine, gas turbine, Diesel engine and industrial furnace applications is reviewed. In some cases, spray combustion can be modeled by ignoring the details of spray evaporation and treating the system as a gaseous diffusion flame; however, in many circumstances, this simplification is not adequate and turbulent two-phase flow must be considered. The behavior of individual droplets is a necessary component of two-phase models and recent work on transient droplet evaporation, ignition and combustion is considered, along with a discussion of important simplifying assumptions involved with modeling these processes. Methods of modeling spray evaporation and combustion processes are also discussed including: one-dimensional models for rocket engine and prevaporized combustion systems, lumped zone models (utilizing well-stirred reactor and plug flow regions) for gas turbine and furnace systems, locally homogeneous turbulent models, and two-phase models. The review highlights the need for improved injector characterization methods, more information of droplet transport characteristics in turbulent flow and continued development of more complete two-phase turbulent models.     

Fuel injection characteristics of diesel‐stimulated natural gas combustion

Although dual‐fuel (DF) engines using a low cetane number primary fuel such as natural gas (NG) ignited by a pilot diesel spray have been the subject of much investigation over years, there are still many unknown problems related to the fundamental combustion process of two fuels. In this work, a quiescent constant volume combustion bomb and a 3‐D numerical model have been used to study the effects of injection nozzle characteristics on the combustion of pre‐mixed NG/air with pilot distillate spray. Experimental tests were conducted on combustion process of pre‐mixed natural gas/air with pilot injection pressure of 30 and 20 MPa with a 4 hole injector, and also with injector nozzle of 8 and 4 holes. The global results obtained from computations compared well with the experimental results. Copyright © 1999 John Wiley & Sons, Ltd.     

某四缸乘用车柴油机燃烧系统的设计优化

介绍了长城汽车研发的一款高性能"2.0VGT"柴油发动机燃烧系统的设计优化过程,通过模拟计算发动机整个工作过程,对进排气系统和进气道形状、气流运动形式、喷油器喷雾特性、燃烧室形状进行多方案优化选型。研究不同工况下,喷油规律(次数、喷油间隔、每次喷油量、喷油时刻)、喷油器特性(喷孔数量、喷孔直径、喷油压力、喷油锥角)的喷雾特性(油滴细化程度、贯穿度)对发动机性能、排放和油耗的影响规律。并对发动机实现国Ⅴ排放要求,对所需要的喷油系统特性及燃烧室形状进行研究。     

低排放单缸风冷柴油机的优化设计与匹配

以非道路单缸风冷192 F柴油机为研究对象,匹配蓄压式喷油系统,以低排放为核心目标,计算并设计了高压油泵凸轮和电控喷油器喷嘴参数,优化了螺旋进气道,重新设计了燃烧室几何形状并优化了喷油油线在燃烧室的分布,使燃烧室、进气道与蓄压式喷油系统相匹配.在标定工况、最大转矩工况下进行了喷油参数对工作过程、排放和性能影响的研究,以...     

限流沿燃烧室中实现柴油喷雾稀扩散燃烧的混合气形成过程

提出了一种在于激光诱导荧光法的实验方案，采用增压式共轨喷油器，在定容燃烧实验装置内进行柴油喷雾形成、发展、撞壁和混合过程的实验。实验发现，燃油喷雾在燃料室壁面的沉积可通过在壁面设置一个“限流沿”（BUMP），使之从壁面剥离，剥离后的壁面射流形成一个迅速扩散的二次空间射流，进而形成较均匀、较稀薄的混合气，它有利于减少碳烟和NOx排放。