中文摘要: 以喷油器喷孔为对象，基于欧拉-拉格朗日法和磨蚀模型对磨粒流研磨过程中的流场及颗粒运动进行了数值模拟,分别得出采用不同形状颗粒时的动压力、湍流动能、颗粒速度、磨蚀速率，探究了颗粒形状因子对研磨结果的影响。研究表明，磨蚀速率同颗粒形状因子成反比关系，采用形状因子较小的颗粒可加快研磨速度，形状因子为0.3的颗粒在喷孔入口处的磨蚀速率最大，比形状因子为0.7的磨蚀速率高出86.6%，颗粒形状对工件表面的磨蚀位置也有较大影响。 英文摘要: Taking an injector nozzle as the research object, the Euler-Lagrange method together with an abrasion model was used to simulate the flow field and abrasive motion during the abrasive flow machining. Then, according to the dynamic pressure, turbulent kinetic energy, abrasive velocity and erosion rate simulated under different abrasive shapes, the influence of abrasive shape factor on erosion effect was explored. Results show that the erosion rate is inversely proportional to the abrasive shape factor. That is to say, use of a smaller abrasive shape factor can increase the erosion rate. The erosion rate with an abrasive shape factor of 0.3 reaches its maximum at the inlet of nozzle, which is 86.6% higher than with an abrasive shape factor of 0.7. Moreover, the shape of abrasive grain also has a relatively large influence on the erosion location of workpiece surface.

中文摘要: 基于某市售1.6 L汽油缸内直喷（GDI）发动机轿车，进行底盘式汽油机颗粒过滤捕集器（GPF）/催化型汽油机颗粒过滤捕集器（CGPF）设计和性能研究，研究了不同涂覆量、涂覆工艺和贵金属含量设计对GPF/CGPF催化剂冷流背压、涂层形貌的影响，从而设计出低背压CGPF催化剂样品。通过对配备有国六标定系统的GDI汽油车进行系列全球统一轻型车测试循环（WLTC）工况排放试验，分别考察了加装底盘式GPF、CGPF及不同贵金属载量CGPF对尾气后处理排放的影响，并与采用原装紧密耦合式三效催化剂（TWC）时的排放性能进行对比分析。结果表明，加装GPF或CGPF配置，会对造成排气系统背压提升，但油耗变化不大；采用紧耦合式TWC+底盘式GPF/CGPF后处理集成净化系统，可有效解决单TWC布局下颗粒物数量（PN）超标问题；使用CGPF可在保证颗粒物捕集效果同时，较好发挥对气态污染物的处理作用，并使各个指标满足国六b排放要求；使用CGPF的催化剂后处理系统进行多次WLTC工况预处理运行，可有效提升其对颗粒物的捕集能力，使PN捕集效率从76.38%跃升至97.00%。 英文摘要: The design and application of an underfloor gasoline particulate filter(GPF) and catalyzed gasoline particulate filter(CGPF) were carried out on a 1.6 litre, direct injection gasoline sedan. The effect of different wash-coat loadings, coating processes and precious metal contents on the cold flow back pressure and coating morphology of the GPF and CGPF systems were studied, and a low back pressure CGPF sample was designed accordingly. Through the worldwide harmonized light vehicles test cycle(WLTC) for gasoline vehicles according to the requirements of CN6 emission regulation, the effect of the underfloor GPF, CGPF and different precious metal contents on exhaust aftertreatment systems were investigated, respectively, by comparing with the emission performance of original close-coupled three-way catalytic converter. Results show that the addition of underfloor GPF or CGPF system downstream of the three-way catalytic converter increases the exhaust back pressure, but does not significantly increase the fuel consumption, which can effectively solve the problem of excessive PN caused by using three-way catalytic converter alone. At the same time, the use of CGPF system can better remove gaseous pollutants while ensuring particulate filtration efficiency, and make various emission indicators meet the requirements specified in CN6 emission regulation. Besides, Preconditioning of the CGPF system according to the WLTC procedure can effectively improve its particulate trapping ability, resulting in an increase of particulate filtration efficiency from 76.38% to 97.00%.

中文摘要: 通过基本结构的微小变动,将单火花塞点火（single spark ignition, SSI）改造成双火花塞点火（dual spark ignition, DSI）,运用三维仿真软件AVL FIRE模拟仿真,并通过试验验证。再对单火花塞点火、双火花塞同步点火（dual synchronous spark ignition, DSSI）、异步点火（dual asynchronous spark ignition, DASI）3种不同的点火方式进行对比。结果表明：在6500 r/min转速全负荷状态下,空气过量系数为1.00而其他参数调整为最佳时,单火花塞的最佳点火提前角为29°,在空气过量系数为1.15的最佳参数下,双火花塞同步点火的最佳点火提前角为22°,双火花塞异步点火的最佳点火提前角为22°和24°。其中,发动机综合性能在双火花塞异步点火条件下表现最好：相对于单火花塞点火指示功提升8.49%；相对于同步点火,可将最高燃烧压力和压缩负功减小,指示功提升3.60%；同时改善了排放性。上述研究中发动机均控制在未发生爆震情况下。 英文摘要: On the basis of only minor modification to the basic structure of a gasoline engine, the original single spark plug ignition was transformed into a double spark plug ignition. And three-dimensional simulation and experimental verification were carried out. Then, a comparative analysis of three different modes of using spark ignition, double spark synchronous and asynchronous ignitions was made. The results of the tests show that at the speed of 6500 r/min and under full load conditions, the best ignition advance angle for the single spark ignition is 29° in crank angle with an excess air ratio of 1.00, and for the double spark synchronous and asynchronous ignitions, the corresponding advance angles are 22°and 22°/24°, respectively, with an excess air ratio of 1.15. As observed, use of double spark asynchronous ignition allows the engine to have the best overall performance. Compared with the single spark ignition, it can increase the available work by 8.49%, and compared with the double spark synchronous ignition, it can improve available work by 3.60% with the reduction of burst pressure and compression work, and hence exhaust emissions. In the above tests, the engine is always controlled to operate in the non-detonation zone.

中文摘要: 采用高温高压定容燃烧弹系统对亚/超临界环境下燃料在纯氧中的喷射燃烧现象进行试验研究,通过高速相机和阴影法进行燃烧图像信息的采集,研究在相同的超临界温度下,正己烷和乙醚两种燃料喷射燃烧火焰特性随环境压力和喷油脉宽的改变而呈现的差异性。试验结果表明：在亚临界压力下,两种燃料在不同喷油脉宽下的燃烧时间均随着环境压力的升高而升高,火焰发展后期基本保持较为稳定的形态和亮度,符合传统的喷射燃烧过程。正己烷在临界压力点下火焰长度最短,形态较为规则；超临界压力下,火焰形态有稳定趋势但仍有轻微波动,且火焰长度略短于亚临界；喷油脉宽改变时,燃烧时间在临界压力附近呈现出不同的趋势。乙醚的燃烧时间随压力的升高而增大,在临界压力处达到最大值,后随着压力的继续升高而下降，不同压力条件下火焰形态略有差别。燃烧现象存在差异性主要是由于亚/超临界坏境下燃料的物性参数和破碎蒸发机理不同。 英文摘要: The combustion phenomena of fuel injection in sub- and super-critical environments was studied by using a constant volume bomb system. The high-speed camera and shadow method were used to collect the combustion image information. The differences in the spray combustion characteristics with the change of ambient pressure and injection pulse width were studied at the same super-critical temperature. The n-hexane and ether were used as fuels in the experiment. Results show that at sub-critical pressure, the combustion time of the two fuels with different injection pulse widths increases with the rise of ambient pressure, while the spray flame maintains a relatively stable morphology and brightness in the later stage of combustion development, which is in line with the traditional spray combustion process. When using n-hexane as fuel, the combustion flame at the critical pressure point has the shortest length and regular morphology. The flame morphology at super-critical pressure trends to be stable with a small fluctuation, and the flame length is slightly shorter than at sub-critical pressure. When the fuel injection pulse width changes, the combustion time will show a different trend near the critical pressure. As for the ether fuel, the combustion time first increases with the rise of ambient pressure, and then decreases after reaching its maximum value at critical pressure. In addition, the flame morphology is slightly different under different pressure conditions. The differences in the combustion phenomena are mainly due to the differences of physical properties and fracture evaporation mechanism of fuels in sub and super-critical environments.

中文摘要: 以两级增压柴油机为研究机型，采用GT Power构建其一维热力学仿真模型，对比模拟研究了柴油机采用两级增压（two stage turbocharger, TST）和可变两级增压（regulated two stage turbocharger, RTST）的变海拔（0 km、2 km、4 km）工作特性。模拟结果表明：针对发动机外特性，不同两级增压系统高压级压比随海拔升高而增加。相比TST增压系统，高原环境下（2 km、4 km），RTST增压系统能够保证更高的进气流量及空燃比，抑制柴油机高原限扭，同时降低有效燃油消耗率。随着海拔升高，TST及RTST涡前温度及传热能均出现不同程度的升高；但RTST涡前温度及传热能升高幅度相对较低。低海拔（2 km）下，NOx 比排放随海拔升高呈增加的趋势。高海拔（4 km）下，可变截面涡轮增压器(variable geometry turbocharger, VGT)开度减小及推迟主喷定时，进气流量及空燃比增加。随着VGT开度增加及主喷定时推迟，涡前温度升高。传热能随VGT开度增加先减小后升高，随主喷定时推迟而减小。NOx 比排放随VGT开度的增加而减小，随主喷定时的推迟减小幅度较小。较早的喷油定时（-7°~-4°）协同合理的VGT开度（0.3~0.5）有利于减小有效燃油消耗率（BSFC）与NOx 比排放的折中关系。 英文摘要: Based on an 1D thermodynamics model set up with the GT-power, the comparative simulation study on the performance of a diesel engine equipped respectively with a two-stage turbocharger(TST) system and a regulated two-stage turbocharger(RTST) system at different altitudes (0 km, 2 km and 4 km) was carried out to achieve high efficiency and low emissions of diesel engines in a plateau environment. The results show that, at full load, the high stage boosting rates of both two-stage turbocharger systems increase with the altitude. Compared with TST, RTST guarantees higher intake air flow and air/fuel ratio(AFR) at the plateau of 2 km and 4 km, thus having less restrain in torque and reducing the brake specific fuel consumption(BSFC). The temperature before turbocharger and heat transfer energy of TST and RTST increase similarly with the altitude, but those of RTST increase less. At the low altitude of 2 km, the specific emissions of NOx increase with the altitude. At the altitude of 4 km, when the opening of the variable geometry turbocharger(VGT) decreases and the start of main injection(SOI) delays, both the intake air flow and AFR increase. With the increase of the VGT opening and the delay of SOI, the temperature before turbocharger rises. The heat transfer energy decreases first and then increases with the increase in the VGT opening, and decreases with the delay of SOI. NOx specific emissions decrease with the increase in the VGT opening, and decrease slightly with the delay of SOI. Earlier SOI (-7° to -4° in crank angle after the top dead center) coordinated with reasonable VGT opening (0.3~0.5) is beneficial to reducing the trade off between BSFC and NOx specific emissions.

中文摘要: 在一台直列4缸增压直喷汽油机上针对万有特性最低油耗工况点，进行了稀薄燃烧与废气再循环（exhaust gas recirculation, EGR）提高发动机热效率的对比试验研究。试验结果表明：稀薄燃烧及EGR均能有效降低发动机燃油消耗率，稀释率分别为33%和19%时，采用稀燃和EGR时的最高有效热效率绝对值分别增加2.8%和1.7%，其中稀燃的有效热效率达到了39.9%，稀燃实现更高热效率主要归因于较低的传热损失和未燃损失。从燃烧角度来看，稀燃及EGR稀释都延长了燃烧滞燃期及持续期，但同样稀释率下稀燃的滞燃期更短，稀燃更高的稀释极限实现了更低的传热损失；但EGR抑制爆震,提前燃烧相位，使采用EGR时的排气能量损失低于稀燃。从排放角度来看，稀燃及EGR在高稀释率下均显著降低NOx 排放，而受益于高氧气浓度，相同稀释率下稀燃的HC及CO排放均低于采用EGR时，从而使稀燃的未燃损失更低。 英文摘要: An inline 4-cylinder turbocharged direct-injection gasoline engine was used to compare the thermal efficiency of the engine with lean burn and exhaust gas recirculation(EGR), and the comparative test was carried out at the lowest fuel consumption point of the universal characteristic curves. The experimental results show that both lean burn and EGR can effectively reduce engine fuel consumption. When the dilution rates of lean burn and EGR are 33% and 19%, their maximum brake thermal efficiencies can increase by 2.8% and 1.7%, respectively, and the brake thermal efficiency with lean burn is even up to 39.9%. The main reason for higher thermal efficiency of using lean burn is the reduction of heat transfer loss and unburned fuel loss. From the view of combustion, the dilution effect of lean burn and EGR extends the ignition delay and combustion duration. At the same dilution rate, the ignition delay with lean burn is shorter than with EGR, and the higher dilution rate of lean burn results in less heat transfer loss. However, use of EGR helps to suppress the occurrences of knock and to advance combustion phase, which makes the exhaust energy loss lower than with lean burn. As to exhaust emissions, both lean burn and EGR can obviously reduce NOx emission at high dilution rate. At the same dilution rate, HC and CO emissions with lean burn are lower than with EGR because of rich oxygen concentration, which results in a much lower unburned loss of lean burn.

中文摘要: 为改善船舶天然气发动机动力系统调速性能，提高内河液化天然气燃料动力船舶的操纵性及安全性，提出构建天然气发动机-蓄电池混合动力系统。分别针对液化天然气发动机动力系统及混合动力系统建立MATLAB/simulink仿真模型，并实现了船舶起动和变负荷过程。然后对两种仿真系统的仿真结果进行分析，结果表明：采用该混合动力系统的船舶变负荷过程航速变化区间变大，并且系统达到稳定时间缩短，采用设计的控制策略，天然气的消耗最大降低量为19.6%、NOX、CO、HC三种排放物最大降低量分别为22.1%、18.5%、23.6%。 英文摘要: In order to improve the speed regulation performance of marine natural gas engine power system and improve the maneuverability and safety of inland liquefied natural gas fuel powered ships, it is proposed to construct natural gas engine-battery hybrid power system. The MATLAB/simulink simulation model was established for the liquefied nat-ural gas engine power system and hybrid system, and the ship starting and changing load process was realized. Then the simulation results of the two simulation systems are analyzed. The variation range of ship speed in the process of changing load with the hybrid power system becomes larger., and the stabilization time of the system is shortened. The maximum reduction of natural gas consumption was 19.6%, and the maximum reductions of NOX, CO, and HC emissions were 22.1%, 18.5%, and 23.6%.

中文摘要: 为了更加高效利用汽油机排气余热，分析了某款汽油机排气余热回收潜力，建立了基于蒸发器和活塞式膨胀机的汽油机-朗肯循环联合余热回收系统模型。利用遗传算法，同时考虑膨胀机输出功、排气利用率、蒸发器效率和膨胀机绝热效率，以膨胀机输出功和系统总效率为优化目标，以蒸发压力和膨胀机转速为优化变量，对汽油机4个工况下朗肯循环系统的最佳运行参数进行了研究。结果表明，在整个发动机转速范围内，排气最大可利用效率均高于46%，转速越高则排气品质越高。在不同工况下存在最优的膨胀机转速和蒸发压力。经过优化，在选取的4个工况下，功率提高率均在6%以上，最高达到7.08%。 英文摘要: In order to utilize gasoline engine waste heat more efficiently, the waste heat recovery potential of a gasoline engine was studied. A model of gasoline engine-Rankine cycle waste heat recovery system based on evaporator and expander was established. By using the genetic algorithm and considering the output and adiabatic efficiency of the expander, the exhaust availability and evaporator efficiency, the optimum operating parameters of the system under four engine operating conditions were optimized with the output power of the expander and the total system efficiency as optimization objectives, the evaporation pressure and expander speed as optimization variables. The results show that the maximum exhaust utilization rate is higher than 46% in the whole engine speed range. The exhaust quality increases with the speed. Under different working conditions, there are the optimum expander speed and evaporation pressure. After optimization, the power under the four selected working conditions is increased by more than 6%, the highest up to 7.08%.

中文摘要: 结合柴油机活塞发展现状,针对某型号高强度柴油机,利用SolidWorks建立该柴油机活塞的三维模型,并用ANSYS对活塞进行有限元分析,讨论活塞在高温环境、最高燃烧压力或最大侧向力作用下的温度场、应力分布和变形情况。分析结果表明,活塞主要承受热应力和热变形,最大耦合应力在油道顶部,约270 MPa,最大变形出现在活塞顶部边缘,变形量约0.08%,变形随活塞高度降低而减小,在裙部略有上升。活塞头部在销孔方向上热变形大于耦合变形,两者差值随活塞头部高度降低而减小。活塞在垂直于销孔轴线方向上的耦合变形总体上大于平行于销孔方向的耦合变形。同时，燃烧室喉口、环槽和销座处应力集中明显,针对上述薄弱区域进行结构改进,发现改进后应力值均显著降低,这些结构改进对高强度柴油机活塞设计开发具有重要指导意义。 英文摘要: Considering the development status of diesel pistons, a three-dimensional model of a heavy-duty diesel piston was established by using SolidWorks software and the finite element analysis was carried out with ANASYS software to analyze the temperature field and the stress and deformation distribution under high ambient temperature and maximum burst pressure or maximum lateral force. Results show that the piston is mainly subjected to thermal stress and deformation. The maximum coupling stress, located at the top of oil gallery, is as high as 270 MPa. The maximum deformation occurs at the top edge of piston with a deformation of about 0.08%. The deformation decreases as the height of piston reduces and rises slightly at the skirt. The thermal deformation of piston head in the direction of pin hole is greater than the coupling deformation, and their difference decreases as the height of piston head reduces. The coupling deformation of the piston in the direction perpendicular to the axis of pin hole is generally greater than in the direction parallel to the axis of pin hole. At the same time, it is found that the stress concentrations at the throat of combustion chamber, the ring groove and the pin seat are relatively obvious. Structural improvements for the above-mentioned weak areas indicate that the stress values are significantly reduced. The improved results have important guiding significance for the future piston design and development of heavy-duty diesel engines.

通过一台6 缸直喷、高压共轨柴油机改装成的柴油引燃天然气发动机．试验研究预喷正时和预喷油量对燃烧参数和性能参数的影响，结果表明：相对单次喷射，较晚的预喷正时(30° CA BTDC)能提高发动机有效热效率(BTE)，降低HC、CO 排放，但NOx排放恶化，而较早的预喷正时(60° CA BTDC)能够在提高发动机BTE 的同时，降低HC、CO 排放，并且NOx 排放基本保持不变；当预喷正时为60° CA BTDC，预喷油量适当增多(3～5 mg/cyc)能进一步提高发动机BTE，降低HC、CO 和NOx排放；预喷油量进一步增加(6～7 mg/cyc)，NOx排放恶化，并且由于着火相位波动导致燃烧稳定性变差．改善双燃料发动机燃烧和排放特性一方面要增加预喷柴油在可燃混合气中的分布，增大柴油与可燃混合气混合的时间，改善混合气的活性，进而提高燃烧速率；另一方面要强化主喷柴油喷射对着火相位的控制，防止着火相位不一致而恶化燃烧稳定性．