针对船用柴油机后处理结构，设计了六种不同的混合器结构，利用计算流体动力学（computational fluid dynamics，CFD）技术对混合器方案进行了仿真分析，对比背压、均匀性、尿素碰壁量、尿素轨迹和流速，选择最优方案，最后通过发动机台架验证其排放性能。CFD及试验结果表明：方案三既能满足背压和NH3均匀性要求，同时尿素结晶风险最小；方案三平均NOx排放为0.66g·kWh-1，满足Tier III排放标准要求，平均NOx转化效率为91.4%，平均NOx转化效率随氨氮比的提高而提高，仿真与试验结果吻合，说明CFD仿真是合理有效的。

Ignition characteristics are of crucial importance for advanced internal combustion (IC) engines operating at low-temperature combustion modes. Recent work shows that fuel reforming has great potential in controlling combustion processes. In this work, cool flame oxidation as a reforming way was proposed and its potential in ignition characteristics was investigated under engine-relevant conditions. As a component of primary reference fuel (PRF), n-heptane was selected for investigations as it has pronounced low-temperature oxidation and cool flame behavior. Depending on fuel oxidation degree at various temperatures, two kinds of reforming products were classified, i.e. mild reforming and severe reforming, manifesting distinct fuel reactivity. Then the influence of forming conditions on reforming products was explored. The effects of reforming products on ignition characteristics of different blends were finally investigated, with detailed sensitivity analysis. The results show that the reforming products via cool flame oxidation are more sensitive to reforming temperature than reforming pressure and equivalence ratio. The majority of reforming products remain unchanged and only some free radicals show significant variations. The promotion effect on ignition processes becomes enhanced by the reforming products from higher temperature, higher pressure, leaner mixture, and severe reforming conditions. Affected by reforming products through cool flame oxidation, the ignition delay time is shortened under most operating conditions, except for some scenarios in the negative temperature coefficient (NTC) range where τ700k, mild>τ700k, severe>τ750k, severe>τ750k, mild, behaving a “cross-point” relation within 700 ~ 750 K.

本文在常压对冲非预混火焰中进行了丁醇同分异构体碳烟生成特性的实验与仿真研究。使用消光法及散射系统进行碳烟体积分数及碳烟颗粒粒径的测量，使用详细气相反应机理进行综合化学动力学仿真。本研究旨在详细分析丁醇同分异构体的碳烟生成特点及同分异构体结构对碳烟生成的影响。结果显示在本研究的不同实验工况下同分异构体的影响是一致的，即四种丁醇的碳烟倾向维持不变，由高到低为：叔丁醇，异丁醇，仲丁醇，正丁醇。

随着排放法规日趋严格，柴油发动机必须配备排气后处理技术，包括包括柴油氧化催化器（DOC）、柴油颗粒捕集器（DPF）和选择性催化还原催化器（SCR）。然而，在后处理系统（DOC+DPF+SCR）与柴油机的最终装配前，必须对催化转化器进行合理的结构优化，并进行大量的台架标定试验，成本高，开发周期长。本文对对某重型柴油机排气后处理系统进行了设计与优化。首先，建立了考虑了催化转化器结构参数的排气后处理系统的一维和三维计算模型。在标定模型的基础上，研究了后处理器结构参数对其主要性能指标的影响，包括各种废气污染物的转化率以及转炉的温度和压降。最后得到了优化设计方案。通过三维模型，研究了载体的温度分布和后处理器的压力分布。本文提出的方法对柴油机后处理系统的优化具有一定的指导意义。

本文搭建了工程船排放测试系统，在线测量了NOx、CO、CO2、THC、颗粒数等常规排放污染物，分析了常规污染物随生物柴油掺混比的变化规律。结果表明，燃用B10生物柴油能有效降低CO、THC排放因子，其中下降最多的分别为为水下泵用柴油机和舱内泵用柴油机；燃用B10生物柴油对NOx排放因子无显著影响，表现为NOx轻微下降；燃用B10生物柴油使得PN和VOCs排放因子增加，其中PN排放因子增加最多的为水下泵用柴油机。

为了满足国六排放法规要求，国际国内天然气主机厂均将国五阶段的稀薄燃烧及EGR技术路线升级为当量燃烧方式加三元催化（TWC）技术路线。发动机燃烧方式及后处理方式的改变，为国六阶段天然气发动机润滑油提出了新的要求。本文采用中国石化润滑油有限公司开发的国六专用长寿命燃气发动机油，在国内主流OEM国六天然气发动机上开展了不同工况台架试验考察。结果表明，开发的长寿命燃气发动机油具有优异的抗氧化性能及清净分散性能，可以较大程度延长换油周期。

In the global background of “Carbon Peak” and “Carbon Neutral”, natural gas shows a great advantage in energy-saving and pollution reduction. However, it suffers from lean combustion instabilities when applied to internal combustion engines. In this paper, the effect of turbulence enhancement on improving lean combustion performance of natural gas was investigated in an optical SI engine with high compression ratios. A variable swirl valve was designed and combined with intake tumble to achieve various turbulent flow and turbulent intensity. Particle image velocimetry (PIV) was employed to measure in-cylinder turbulent flow and high-speed photography was employed to capture combustion evolutions. The results show that in-cylinder turbulent intensity is enhanced as swirl is increased. There is little variation in the sensitivity of IMEP to spark timing, but the increase of combined-turbulence will greatly increase flame propagation speed and improve thermal efficiency. The analysis of flame images shows that turbulence intensity gradually increases in the radial orientation from the spark plug to the cylinder wall, which leads to an earlier flame kernel and a faster burning rate. This combined-turbulence can reduce the cyclic variations of early flame development and optimize the whole combustion process.

温差发电器能够直接转化低品位的热能至电能，但是它的能量转化效率较低。因为温差发电器的输出特性受温度和负载的影响，它不能够一直保持最大的输出功率。为了分析含有最大功率点追踪算法的SEPIC DC-DC逆变器对温差发电器输出性能的影响，利用MATLAB/SIMULINK建立了两类模型，也就是温差发电器直连负载模型和通过含最大功率点追踪算法的SEPIC DC-DC逆变器连接模型。两类模型的输出特性，也就是电压、电流、功率、效率被比较和分析。结果表明直接连接仅适用于负载电阻与温差发电器内阻接近时，而含有最大功率点追踪算法的逆变器在负载电阻偏离温差发电器内阻时效率更高。后者可以使温差发电器运行在最大功率点，尽管会造成一定的功率损失。

采用硬度测试、拉伸性能测试、晶间腐蚀实验和TEM等检测方法，研究双级时效对6056铝合金组织和晶间腐蚀性能的影响。结果表明，合金在T6处理时，硬度约为136HB，合金强度为409.5Mpa,伸长率为17.1%，晶间腐蚀深度为527μm；T6+140℃/8h,T6+160℃/6h和T6+190℃/4h状态下时，合金硬度与T6时相差均不大，强度略微增加，晶间腐蚀深度分别为231μm，276μm和637μm，综上所述，最佳双级时效工艺为T6+140℃/8h。经TEM分析，T6处理时，晶內主要析出的针状QC相和QP相与少量板条状的Q'相，晶界上出现断续的析出相，晶界周围出现无沉淀析出带(PFZ),PFZ区域宽度为110nm；经T6+140℃/8h双级时效处理后，晶內针状析出相数量和尺寸略微增加，板条状析出相变化不大，晶界上析出相数量减少，析出相间距增大，PFZ区域宽度缩小一倍，约为55nm，因此相对于T6态而言T6+140℃/8h双级时效处理可以不损失力学性能的同时而大大提升耐晶间腐蚀性能。

本文采用一种新的3D+1D多相流模型，对金属泡沫流场质子交换膜燃料电池的稳态和瞬态特性进行了详细的研究。结果表明，泡沫金属流场能改善质子交换膜燃料电池的稳态性能，特别是在高电流密度下。此外，金属泡沫流场使得氧气、电流密度、温度和液态水的分布更加均匀，有利于提高电池的性能和耐久性。在瞬态特性方面，结果也表明金属泡沫流场有助于质子交换膜燃料电池的稳定运行。