中文摘要: 内燃机工作时依赖冷却系统将多余热量及时带走以保证燃烧室核心部件及润滑油膜的正常工作温度。常规内燃机冷却介质导热系数偏低，而新一代强化传热工质纳米流体具有明显提升的传热性能，应用于内燃机冷却系统有利于强化内燃机传热及提高热管理性能。且由于纳米流体的传热性能受纳米粒子的种类、大小、浓度、形状等因素影响，可以通过改变这些因素控制内燃机冷却水腔的传热量。综述了国内外研究者针对纳米流体导热系数与对流换热性能开展的试验测试、理论分析和计算机模拟研究工作，以及纳米流体应用于内燃机冷却系统中强化传热的进展，最后指出当前研究工作的不足及未来工作方向。 英文摘要: Internal combustion engine relies on its cooling system to take away the excess heat and control the normal operating temperatures of the core components of the combustion chamber and the lubricating oil film, wherein the heat transfer performance of the conventional cooling mediums is generally low. Nanofluids, as the new generation of enhanced heat transfer working medium, has good heat transfer performance, which is ideal for the cooling system of internal combustion engine to use it to enhance heat dissipation and improve thermal management performance. Moreover, because the heat transfer performance of the nanofluids is affected by factors such as the type, size, concentration and shape of the nanoparticles, the heat transfer amount of the cooling water chamber of the internal combustion engine can be controlled by changing these factors. This paper reviews the experimental, theoretical and computer simulation studies conducted by researchers on the thermal conductivity and convective heat transfer performance of nanofluids, as well as the application of nanofluids in enhancing heat transfer of internal combustion engine. Finally, it points out the shortcomings of the current research work, and the future work directions.

中文摘要: 为探究催化型柴油机颗粒捕集器（catalytic diesel particulate filter， CDPF）的再生性能，自制了CDPF颗粒加载装置，通过模拟气试验平台研究了炭载量、再生温度及气体流量对CDPF再生性能的影响，并对其再生效率、再生效能比、最高温度及最高温度梯度性能指标进行评价。试验结果表明：CDPF再生过程主要有两个阶段，第一个阶段主要发生在250~400 ℃之间，为低温长时间再生阶段；第二个阶段主要发生在500~600 ℃之间，为高温短时间再生阶段。当再生温度为350 ℃、气体流量为200 mL/min时，3.2 g/L、5.0 g/L和7.0 g/L 3种炭载量下的最高温度梯度均达到最小，分别为2737.5 ℃/m、4387.5 ℃/m和3837.5 ℃/m。其再生效率在再生温度为250 ℃时均约为6.0%，而在550 ℃时均达到85.6%。当炭载量为5.0 g/L，再生温度为500 ℃和550 ℃，气体流量为300 mL/min时，最高温度、最高温度梯度及再生效率均达到最大，再生效能比随气体流量的增大从4.6×10-5 J-1下降到1.8×10-5 J-1。 英文摘要: In order to explore the regeneration performance of catalytic diesel particulate filter(CDPF), an in-house-made CDPF carbon particle loading device was developed. The effects of carbon loading, regeneration temperature and gas flow rate on the regeneration performance of CDPF were studied through a simulated gas test platform, and the regeneration efficiency, regeneration efficiency ratio, maximum temperature and maximum temperature gradient were evaluated. The results show that there are two main stages in the CDPF regeneration. The first stage mainly takes place between 250 ℃ and 400 ℃, which is a long regeneration at low temperatures; the second stage mainly occurrs between 500 ℃and 600 ℃, which is a short regeneration at high temperatures. When the regeneration temperature is 350 ℃ and the gas flow rate is 200 mL/min, the maximum temperature gradients of 3.2 g/L, 5.0 g/L and 7.0 g/L carbon loading are the smallest, being 2737.5 ℃/m, 4387.5 ℃/m and 3837.5 ℃/m respectively. The regeneration efficiency is about 6% at 250 ℃, and 85.6% at 550 ℃. When the carbon loading is 5.0 g/L, the regeneration temperature is 500 ℃ and 550 ℃ and the gas flow rate increases to 300 mL/min, the maximum temperature, the maximum temperature gradient and the regeneration efficiency all reach the highest, and the regeneration efficiency ratio decreases from 4.6×10-5 J-1 to 1.8×10-5 J-1 with the increase in the gas flow rate.

《内燃机工程》2020年第2期目次

目次

《内燃机工程》2020年第1期目次

中文摘要: 针对强噪声干扰下柴油机失火故障难以诊断的问题，提出一种基于变分模态分解（variational mode decomposition, VMD）与交叉小波变换（cross wavelet transform, XWT）的柴油机失火故障诊断方法。该方法首先通过VMD将缸盖振动信号进行分解、自适应消噪及信号重构，再利用XWT对任意两个连续工作循环信号进行时频相关分析，进一步消除振动信号中的干扰噪声以提取柴油机燃烧特征，最后通过计算时频空间各缸能量占比进行柴油机失火故障诊断。通过对仿真信号分析及柴油机失火故障诊断，结果表明：该方法可以消除强噪声干扰，提取柴油机燃烧周期瞬态振动冲击特征，有效地识别柴油机失火故障。 英文摘要: Aiming at the problem that diesel engine misfire is difficult to diagnose under strong noise interference, a diesel engine misfire fault diagnosis method based on variational mode decomposition(VMD) and cross wavelet transform(XWT) is proposed. Firstly, cylinder head vibration signal is decomposed, denoised and reconstructed by VMD, and then the time-frequency correlation analysis on any two consecutive operating cycle signals is carried out by using XWT to extract the diesel combustion features after eliminating the interference noise in the vibration signal, and finally the diesel engine misfire fault diagnosis is performed by calculating the energy ratio of each cylinder in the time frequency space. Simulation and analysis results show that the method can eliminate the strong noise interference, extract the transient vibration shock features in diesel engine combustion cycle and effectively identify the diesel engine misfire fault.

中文摘要: 对大功率发电柴油机选择性催化还原（selective catalytic reduction,SCR）尿素喷雾锥角进行研究。运用计算流体动力学（computational fluid dynamics,CFD）软件模拟了4种不同喷雾锥角尿素混合管内的结晶风险和NH3 分布均匀性,通过分析仿真结果,优选出60°和70°两种喷雾锥角的尿素喷嘴。使用选定的喷雾锥角进行结晶对比试验和性能对比试验。结晶对比试验结果显示,60°喷雾锥角的结晶风险明显低于70°喷雾锥角的结晶风险。性能对比试验结果显示,两种喷雾锥角的NOx 转化效率基本一致。综合分析仿真结果与试验结果,最终将SCR系统的尿素喷雾锥角优化为60°。 英文摘要: The urea spray cone angle of a selective catalytic reduction (SCR) system used on a high-power generating set diesel engine was studied. The crystallization risk and NH3 distribution uniformity in an urea mixing pipe with 4 different spray cone angles were simulated by a computational fluid dynamics software. Through the simulation analysis, two kinds of urea nozzles with spray cone angles of 60° and 70° were selected for the crystallization contrast test and performance comparison test. The results of the crystallization contrast test show that the crystallization risk of the 60° spray cone angle is obviously lower than the 70° spray cone angle. The performance comparison test indicates that the NOx conversion efficiencies of the two spray cone angles are basically the same. After the comprehensive analysis of the simulation calculations and test results, the urea spray cone angle of the SCR system is finally optimised to 60°.

中文摘要: 基于弹流润滑（elastic hydrodynamic lubrication，EHL）和粗糙峰接触理论及平均流量模型，建立了某连杆小头摆动摩擦副柔性多体动力学模型，分析研究了抛物型线、双曲型线和锥度型线3种衬套型线对连杆小头摆动摩擦副润滑及变形匹配的影响。结果表明：抛物型线与双曲型线的润滑和变形特性都要优于无型线；而锥度型线润滑性能变差，变形特性能得到提升；综合来看，切削量为6μm的双曲型线对连杆小头衬套润滑和变形匹配的综合改善效果较好。 英文摘要: Based on the theory of elastic hydrodynamic lubrication and rough peak contact and the average flow model, a flexible multi-body dynamics model of the swinging friction pair of a connecting rod small end bushing was established, and the effect of the different profiles of the bushings, including parabolic, hyperbolic and tapered profiles, on lubrication and deformation of their swinging friction pairs was analyzed. Results show that compared with plain type bushing, the bushings with parabolic or hyperbolic profiles have better lubrication and deformation characteristics, while the bushing with a tapered profile has poor lubricity, but its deformation characteristics is better. In summary, use of hyperbolic profile with a cutting amount of 6 um can greatly improve the comprehensive characteristics of lubrication and deformation of the connecting rod small end bushings.

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%.