一种新型燃气机一涡旋式发动机的理论研究

涡旋式机械首先在压缩机领域，尤其是制冷压缩机领域获得了成功应用，并取得了成就，但涡旋式机械用于发动机才刚刚开始，许多基本方面有待深入研究、分析。本文介绍燃气循环涡旋式发动机的构成特点，对理论循环进行初步分析，并探讨实现燃气涡旋式发动机的一些技术措施。     

一种新型燃气机—涡旋式发动机的理论研究

涡旋式机械首先在压缩机领域，尤其是制冷压缩机领域获得了成功应用，并取得了成就，但涡旋式机械用于发动机才刚刚开始，许多基本方面有待深入研究，分析，本文介绍燃气循环涡旋式发动机的构成特点，对理论循环进行初步分析，并探讨实现燃气涡旋式发动机的一些技术措施。     

4100QBZ柴油机高压共轨系统喷油嘴匹配及优化

为将BOSCHCR高压共轨系统应用在4100QBZ柴油机上,进行了BOSCH喷油嘴与4100QBZ柴油机燃烧室的匹配。遵循油束沿燃烧室轴向和径向分布均匀匹配的原则,计算了喷油嘴的结构参数;用KIVA软件建立喷油嘴和燃烧室燃烧网格模型,优化喷油嘴参数。用等圆弧分布和等体积的方法得到四组BOSCH喷油嘴方案;对不同喷油嘴进行燃烧计算,以最高燃烧压力和燃油消耗率为指标,选取合理的喷油嘴参数。     

新型涡旋式机械原理及其在内燃机中的应用（2）

新型涡旋式机械原理及其在内燃机中的应用（２）西安交通大学顾兆林，郁永章３涡旋式燃气机本文的第一部分介绍了涡旋式内燃机的结构特点及工作原理，它是一种火花点火发动机。改变燃烧放热方式，即把内燃方式加热改成外燃方式加热，涡旋式内燃机可演化成涡旋式燃气机。同...     

K系数喷油嘴的CFD计算及试验研究

应用AVL FIRE软件,对k系数喷油嘴进行了三维流动计算,并在CA4DC2柴油机上进行了k=1.5和k=0喷油嘴的对比试验研究,试验结果表明:k=1.5系数喷油嘴全面改善了柴油机的性能指标.     

涡旋式内燃机工作过程的分析研究

与往复式内燃机和其他旋转发动机不同，涡旋式发动机有许多鲜明的特点。本文对涡旋式发动机的吸气过程，动力过程以及排气过程等与往复式内燃机进行了比较分析和研究，揭示了涡旋式发动机的一些优点。     

机车柴油机用喷油嘴偶件流量的试验研究

通过稳态高压液体流量的试验,初步掌握了机车柴油机用喷油嘴偶件的流量系数和流量分散度的现状,分析了影响喷油嘴偶件流量的因素。介绍了应用液体挤压研磨技术提高机车柴油机用喷油嘴偶件流量的效果。     

喷油嘴偶件喷孔防积炭涂层的研究

通过对喷油嘴偶件针阀体喷油端的外表面及喷孔的孔壁进行防积炭涂层处理,从而防止和减少喷油嘴偶件喷油端和喷孔积炭的附着,提高喷油嘴偶件的使用性能,延长喷油嘴偶件的使用寿命,研究人员通过对该防积炭喷油嘴偶件进行流量对比试验和热机试验,验证了该喷油嘴偶件产品经过涂层处理后所表现出来的功能优势。     

柴油机喷油嘴结构对内部空穴流动的影响分析

利用混合多相流空穴模型对垂直多孔喷油嘴完全发展了的空穴流动进行三维数值模拟,分析了不同的喷油嘴压力室结构、喷油嘴喷孔入口圆角半径和喷孔倾斜角等对喷油嘴内部空穴流动的影响,为喷油嘴结构优化设计提供了指导:改进型(IMPROVED)喷油嘴综合特性优于标准型(STD)和无压力室型(VCO)喷油嘴;喷孔入口锐边过渡使喷孔空穴层基本均可延伸至喷孔出口,形成"超空穴"现象,加速液流紊乱,可提高雾化质量.     

两种轴针式喷油嘴喷油过程的测试对比研究

本文对节流轴针式和普通轴针式喷油嘴的喷油过程进行实验研究,试验结果表明,节流轴针式喷油嘴应用在小缸径柴油机上能取得良好的喷油特性和喷雾质量。     

Effects of swirl on the stability of jet diffusion flames

An experimental study was made, using a double-swirl burner, of the stability of swirling-fuel-jet diffusion flames in swirling air streams. The fuels were hydrogen and methane. The primary variables studied were swirl intensities of the fuel jet and the air stream. It was found that the stability of flame depended on the swirl intensity of both the fuel jet and the air stream. The application of swirl to the fuel jet decreased the rim stability of the flame, but increased the blowout stability of the lifted diffusion flame. For low swirl intensity of the air stream, the effect was similar to that of the fuel jet. At higher swirl intensities of the air stream, above a critical value, the flame stability increased noticeably because of the formation of a recirculation zone near the injector exit. Even in strongly swirling air streams, the favorable effect of fuel swirl on stability of the lifted flame was evident, particularly for the methane flame.     

在柴油机上应用涡流喷嘴的探索

通过对涡流喷嘴的特点和应用现状的分析，探讨在柴油机上运用涡流喷嘴会对柴油机动力性、燃油经济性和废气排放性能等方面产生的影响。提出了实现涡流喷嘴在柴油机上应用的实际困难及所要做的工作。     

涡流运动降低柴油机混合气浓度及碳烟排放的数值分析

为了揭示涡流运动对柴油机混合气形成及碳烟排放的影响规律，采用经过实验验证的喷雾及湍流模型，用CFD数值分析软件对某车用柴油机燃烧室内不同涡流条件下柴油喷雾的混合气浓度、速度矢量场、燃油液滴空间分布及油束特性进行了模拟计算．模拟结果表明，当涡流比从0到5．0依次增大时，过喷孔轴线的铅垂面内喷雾浓度场局部浓区燃空当量比逐渐降低，而过喷孔轴线且与铅垂面垂直的平面内喷雾浓度场局部浓区的燃空当量比则先降后升，而不是逐渐下降．只有合理选择剖切平面，即选择过喷孔轴线且与铅垂面垂直的平面，才能正确评价涡流运动对燃烧室内混合气浓度分布及碳烟形成区域分布的影响规律．组织燃烧室内气流运动，须兼顾与气缸轴线垂直的水平面内的涡流运动和过气缸轴线的铅垂面内的湍流或滚流运动．涡流比太大，铅垂面内的湍流或滚流太弱，会削弱喷雾射流对燃烧室底部空气的卷吸，降低燃烧室底部的空气利用率．随涡流比增大，射流顺涡流方向的弯曲度增大，不同喷孔的油束会发生相互干涉，在靠近气缸中心的区域内形成局部浓混合气，不利于降低碳烟排放．对具体的燃烧室结构和喷油系统，合理匹配涡流运动十分必要．     

High swirl-inducing piston bowls in small diesel engines for emission reduction

Detailed three-dimensional CFD simulations involving flow and combustion chemistry are used to study the effect of swirl induced by re-entrant piston bowl geometries on pollutant emissions from a single-cylinder diesel engine. The baseline engine configuration consists of a hemispherical piston bowl and an injector with finite sac volume. The first iteration involved using a torroidal, slightly re-entrant bowl geometry, and a sac-less injector. Pollutant emission measurements indicated a reduction in emissions with this modification. Simulations on both configurations were then conducted to understand the effect of the changes. The simulation results indicate that the selected piston bowl geometry could actually be reducing the in-cylinder swirl and turbulence and the emission reduction may be entirely due to the introduction of the sac-less injector. In-cylinder air motion was then studied in a number of combustion chamber geometries, and a geometry which produced the highest in-cylinder swirl and Turbulence Kinetic Energy (TKE) around the compression top dead centre (TDC) was identified. The optimal nature of this re-entrant piston bowl geometry is confirmed by detailed combustion simulations and emission predictions.     

Parametric studies for improving the performance of a Jatropha oil-fuelled compression ignition engine

A single cylinder, constant speed, direct injection diesel engine was operated on neat Jatropha oil. Injection timing, injector opening pressure, injection rate and air swirl level were changed to study their influence on performance, emissions and combustion. Results have been compared with neat diesel operation. The injection timing was varied by changing the position of the fuel injection pump with respect to the cam and injection rate was varied by changing the diameter of the plunger of the fuel injection pump. A properly oriented masked inlet valve was employed to enhance the air swirl level. Advancing the injection timing from the base diesel value and increasing the injector opening pressure increase the brake thermal efficiency and reduce HC and smoke emissions significantly. Enhancing the swirl has only a small effect on emissions. The ignition delay with Jatropha oil is always higher than that of diesel under similar conditions. Improved premixed heat release rates were observed with Jatropha oil when the injector opening pressure is enhanced. When the injection timing is retarded with enhanced injection rate, a significant improvement in performance and emissions was noticed. In this case emissions with Jatropha oil are even lower than diesel. At full output, the HC emission level is 532 ppm with Jatropha oil as against 798 ppm with diesel. NO level and smoke with Jatropha oil are, respectively 1162.5 ppm and 2 BSU while they are 1760 ppm and 2.7 BSU with diesel.     

Spray characteristics of high-pressure swirl injector fueled with alcohol

The spray characteristics of methanol and ethanol with high-pressure swirl injector were explored experimentally and numerically. experimental results show that the spray characteristics of methanol and ethanol had displayed the same trends as that of gasoline. Under the low back-pressure ambient conditions, the spray behavior exhibited a hollow cone with wide spray angle and initial spray slug at the tip, while the spray presented a solid cone in the case of high back-pressure. Vortexes in the opposite direction existed in the rear part of the spray under low back-pressure ambient conditions while the vortexes formed in the middle part under high back-pressure ambient conditions. Experiments also showed that methanol had the largest cone angle, while ethanol and gasoline presented almost the same cone angle. Simulation results indicated that methanol and ethanol had a slightly larger Sauter mean diameter (SMD) than that of gasoline with swirl injector. The SMD profile of methanol coincided well with that of ethanol under low back-pressure ambient conditions, but displayed a slightly larger value under high back-pressure due to fuel evaporation Numerical simulation could successfully demonstrate the spray characteristics of high-pressure swirl injector for methanol and ethanol fuels. Translated from Transactions of CSICE, 2006, 24(1): 1–8 [译自: 内燃机学报]     

非道路柴油机进气及喷油系统的虚拟优化匹配

采用三维计算流体力学(CFD)技术模拟了柴油机的进气、压缩、喷雾和燃烧过程,通过组合不同的进气涡流和喷油嘴方案找出各自对柴油机排放的影响,结果表明,降低进气涡流,提高流量系数;减小喷油器安装倾角,缩小喷孔孔径,推迟喷油提前角可以实现NO排放和SOOT排放的全面降低。此外,对2款单缸柴油机的喷油嘴互换性也进行了适当的分析。     

OPTIMIZED DESIGN OF A NEW GASOLINE DIRECT SWIRL INJECTOR

The internal flow characteristics of a gasoline direct injector (GDI) have been studied to improve fuel economy and reduce exhaust emissions. Computational fluid dynamics (CFD) is used to examine the internal flow of the GDI with the purpose of designing the optimum geometry of the injector. The design parameters include orifice length, cone angle, swirl angle, orifice diameter, and needle lift. Numerical results show that optimum sizes of the orifice length, cone angle, swirl angle, orifice diameter, and needle lift are 0.8 mm, 140°, 120°, 0.8 mm, and 70 m, respectively. The size of the lift does not affect the formation of the air core significantly near the tip of the needle compared with the ball-type needle. The vena contracta phenomenon near the orifice inlet can be released by smoothing the edge.     

单缸柴油机双喷油器燃烧系统的研究

本文介绍了柴油机双喷油器燃烧系统的结构和工作原理，在小缸径柴油机上使用双喷油器燃烧系统可以增加喷注的自由贯穿长度，使喷注得以充分扩散，从而促进柴油和空气的混合，提高混合气形成质量，改善燃烧过程，同时，可以降低对进气涡流的要求，增加气门流通面积，减少流动损失。采用该燃烧系统，还可以减少气缸盖的热负荷，可实现先缓后急的喷油规律，降低柴油机的工作粗暴性和燃烧噪声。     

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。