基于仿真计算的船用柴油机性能优化研究

以某船用大功率高增压柴油机为研究对象,采用一维工作过程软件进行仿真计算,研究不同排气管方案和不同米勒正时方案对柴油机性能的影响规律。结论是:通过匹配柴油机排气能量利用率更高的排气管和适当强度的米勒正时,可以在满足排放法规的前提下,降低柴油机热负荷和燃油消耗率,有利于提高柴油机的可靠性和经济性。     

柴油机工作过程故障灰色诊断专家系统

阐述了一个柴油机工作过程故障灰色诊断专家系统的构造过程。此系统采用压力和温度传感器采集到的气缸内压力,机油夺力和温度,进,排气压力和温度,供油压力等参数,建立一个各种状态下的参数库。利用灰色关联库理论的方法,对柴油机各种故障状态进行分析诊断,查找故障,分析原因,软件设计,按照专家系统的设计思想,利用Ｖｉｓｕａｌ面向对象的程序设计方法,设计了一个柴油机工作过程故障诊断专家系统,并在Ｓ１９５型柴油机上     

大气环境下柴油机尾排气管口边界条件及声辐射

在用不稳定流动方法模拟柴油机大气环境条件下排气噪声中，本给出了考虑尾管口处压力波动的非等熵准定常边界条件，而在排气声辐射采用Ｈｏｗｅ公式。两相结合，能够从管口透射声功率的角度从管口辐射噪声进行更为合理的描述。     

基于欧VI排放标准的中型柴油机排气热管理试验研究

尾气后处理的转化效率受排温影响,而柴油机中低负荷下排温较低,难以满足要求。以某中型柴油机为对象,针对影响排温的进气节流阀(IAT)、电控废气旁通阀(EWG)和排气背压阀(EAT)进行了中低负荷稳态点控制策略的试验研究。试验结果表明:在满足低排放和低油耗的前提下,仅靠单一排气热管理措施难以提高排温,须两种或两种以上措施合理匹配,共同作用。基于此,提出了可行的排气热管理方案,并在WHTC测试循环下验证了该方案可使试验柴油机在保证经济性和排放的变化在可接受范围内,满足排温要求。     

温度对NTP喷射系统处理柴油机模拟排气的影响

为研究低温等离子体活性物质对柴油机有害排放物的去除效果,自行设计了介质阻挡放电型低温等离子体反应器。采用独立于柴油机排气管之外的低温等离子体喷射系统,研究其在不同的柴油机模拟排气温度下,对各排气成分的转化效果。研究结果表明:在低温等离子体环境下,NO主要转化为NO2;O3对NO和HC有较强的氧化作用;高温不利于NO的转化和O3的产生,但有利于HC的氧化,同时产生CO;温度和激励峰峰值电压的变化对CO2浓度基本没有影响。     

Performance of a stationary diesel engine using vapourized ethanol as supplementary fuel

The modification and testing of a compression ignition engine using diesel and vapourized ethanol as fuel has been carried out. Tests on the engine fuelled with diesel only were made, and the performance evaluated to form a basis for comparison for those of ethanol–diesel dual fuelling.

Modifications were made in the introduction of the ethanol and air. A carburettor was used to vapourize aqueous ethanol into the engine. The effect of preheating the intake ethanol–air mixture was also investigated. Performance was evaluated in terms of engine horsepower, brake specific fuel consumption, brake thermal efficiency, the exhaust gas temperature, lubricating oil temperature and exhaust emissions. The vapourized ethanol partially reduced diesel fuel consumption but also increased total fuel delivery. Vapourization increased power output, thermal efficiency and exhaust emissions but lowered exhaust temperature and lubricating oil temperatures.     

管流中沉降微粒团再悬浮控制因素分析

沉降微粒再悬浮受微粒团直径、气流速度、微粒团与壁面间的黏附状况以及管道情况等多种因素的作用,是柴油机排气微粒净化捕集及微粒采样过程中的一个重要现象.以管流中的柴油机排气沉降微粒为研究对象,利用建立的沉降微粒团再悬浮静态受力模型,对管流中沉降微粒团再悬浮的控制因素进行了分析.研究结果表明,微粒团黏附角、平均流速以及管径等因素对管流中沉降微粒团的再悬浮具有重要的影响.通过研究,得到了微粒团黏附角、平均流速以及管径等控制因素对管流中沉降微粒团再悬浮的影响规律.     

基于AR模型和K-L信息量的柴油机气阀机构故障诊断

通过模拟气阀机构的两种常见故障:气阀漏气和气阀间隙异常,采集柴油机缸盖表面的振动信号.提出了柴油机气阀机构的状态监测及故障诊断策略,采用FPE准则和Burg算法建立不同状态时振动信号的AR模型,利用K-L信息量对不同工作状态进行了有效识别.诊断结果表明该方法是可行的,便于实现柴油机气阀机构故障的在线实时监测与诊断.     

４９３ＺＱ柴油机匹配气波增压器的研究

介绍了在４９３ＺＱ柴油机上匹配大容积进气管、渐扩式排气管的方法,以及在气波增压器与发动机之间寻找理想的转速比,对气波增压柴油机的性能及排气净化进行的试验研究,获得了实用的匹配规律。试验结果证明,与原涡轮增压样机相比,采用变速比的气波增压样机具有非常优良的排放性能和瞬态响应性能,同时还具有良好的动力性、经济性、加速时不冒黑烟,彻底克服了涡轮增压柴油机瞬态响应滞后、低速供气量小的弱点。采用新型转子的ＣＸ－１０２型气波增压器有效地降低了噪声。     

Prediction of marine diesel engine performance under fault conditions

The diesel engine, due to its superior efficiency when compared to other thermal engines, is widely used for propulsion of marine vessels. Since in such applications the power concentration is critical, most marine diesel engines are of the turbocharged type. Turbocharging has a serious effect on engine performance due to the interaction between the turbocharger and the engine. This interaction makes the detection of engine faults extremely difficult since a specific fault affects the turbocharger and through it the engine. For this reason various methods have been proposed for the detection of engine faults. The present author has in the past presented a method for marine diesel diagnosis by processing measured engine data using a simulation model. In the present work a completely different approach is followed; an attempt is made to use a simulation model to predict marine diesel engine performance under various fault conditions. The method is applied to a newly built vessel powered by a slow speed two stroke marine diesel engine. Using the engine shop trial data obtained under propeller law the simulation model constants are determined, using an automatic method that has been developed. The comparison of results obtained with the data from the official shop trials confirms the accuracy of the model and its ability to predict almost all operating parameters of the engine. The model is then used to produce results by simulating various engine faults or faults of its subsystems. From this analysis their impact on various measurable engine parameters is determined. It is interesting to see that in the case of turbocharged engines some faults have a different effect when compared to naturally aspirated ones. Also, it is revealed that without the use of modeling in many cases it is relatively difficult to determine the actual cause for an engine malfunction, since the observed effects on engine performance are similar. The proposed method is promising and assists the engineer to understand the actual effect of various faults on engine performance. Also it can be used as a training tool since it is easy to simulate various engine faults, a procedure which is extremely difficult, if not impossible, to perform on the field.     

柴油机排气管隔热技术现状

柴油机排气管隔热技术的应用己有几十年的历史，至今大多数柴油机的隔热技术仍与用户的需求有较大的差距。本文考察了柴油机排气管隔热所使用的材料、技术及隔热效果等问题，特别是侧重对所应用的材料做了进一步的分析，并对今后隔热稳定性方面的工作进行了初步的讨论。     

Numerical investigation of flow mixture enhancement and infrared radiation shield by lobed forced mixer

For the exhaust system of turbo-fan engine, the numerical calculation is used to investigate the different mixer configurations. The method using forward–backward ray-tracing and narrow-band model to predict the radiation from engine exhaust has been developed. The scheme has been validated in accuracy for spectral radiation intensity predictions, and some useful results of practical importance have been obtained to establish its ability for infrared signature analysis of exhaust system. A series of computations on exhaust system model have been conducted to obtain the effects of mixer configuration on the aerodynamic performances and infrared radiation intensity. The results indicate that the lobed forced mixer can increase the mixing efficiency by 65%, decrease the thrust coefficient by 3% only, but the infrared radiation of plum can reduce about 40% relative to confluent mixer at zero degree aspect (normal to nozzle outlet), especially. That means the lobed forced mixer has the remarkable ability to shelter the infrared radiation from the inside enclosure of nozzle.     

The effect of clove oil and diesel fuel blends on the engine performance and exhaust emissions of a compression-ignition engine

Diesel engines provide the major power source for transportation in the world and contribute to the prosperity of the worldwide economy. However, recent concerns over the environment, increasing fuel prices and the scarcity of fuel supplies have promoted considerable interest in searching for alternatives to petroleum based fuels. Based on this background, the main purpose of this investigation is to evaluate clove stem oil (CSO) as an alternative fuel for diesel engines. To this end, an experimental investigation was performed on a four-stroke, four-cylinder water-cooled direct injection diesel engine to study the performance and emissions of an engine operated using the CSO–diesel blended fuels. The effects of the CSO–diesel blended fuels on the engine brake thermal efficiency, brake specific fuel consumption (BSFC), specific energy consumption (SEC), exhaust gas temperatures and exhaust emissions were investigated. The experimental results reveal that the engine brake thermal efficiency and BSFC of the CSO–diesel blended fuels were higher than the pure diesel fuel while at the same time they exhibited a lower SEC than the latter over the entire engine load range. The variations in exhaust gas temperatures between the tested fuels were significant only at medium speed operating conditions. Furthermore, the HC emissions were lower for the CSO–diesel blended fuels than the pure diesel fuel whereas the NO_x emissions were increased remarkably when the engine was fuelled with the 50% CSO–diesel blended fuel.     

柴油机二相深度净化装置的设计研究

为了降低柴油机车尾气的主要污染物Nox和颗粒,采用传统固态和液态二相净化处理相结合的方法,设计一种新型二相深度净化装置.结果表明,在190柴油机进行的外特性试验过程中,颗粒的整体排放均有下降;在自由加速试验中,烟度平均值降低了70.4%.     

乙醇掺混燃烧对柴油机油耗影响的实验研究

乙醇吸热后部分热解可产生多种气体的混合物,为了研究气体混合物掺混燃烧在柴油机上的节油效果,对柴油机系统进行了改造:乙醇通过安装在柴油机排气管上的小型高效换热器吸收烟气余热,部分热解后混合气体由进气道通入柴油机燃烧室改善燃烧.在该系统上进行了定功率-不同转速以及额定转速-不同功率下的节油试验,表明:该系统在高低功率条件下均有较好的节油和节能效果.柴油机转速为1 500 r/min时,节油率最高可达40％,节能率最高可达13.5％;在柴油机额定转速2 000 r/min时,节油率最高可达24％,节能率最高可达5.7％.结合乙醇热解的气体混合物的测量数据,得出了低功率下主要依靠乙醇蒸气,高功率下主要依靠小分子气体的节油原理.     

水下柴油机工作特性研究

建立了包括调速器、柴油机本体、后排气管路的水下柴油机动力系统的动态及稳态过程分析模型,并进行了试验验证。通过后排气管路的三维流动计算、整机性能计算和相关试验研究,确定了柴油机水下运行不倒灌水的判据,并给出了单机和双机运行的安全范围。研究了启动及停机过程中,后排气管压力、排气排水流速及发动机转速的变化规律。在启动过程中,排气速度不是单调上升,而是有振荡现象,在振荡过程中,有可能发生海水倒灌;在停机过程中,应根据后排气管压力变化控制排气外舌阀的关闭过程,以防止海水倒灌及排气背压过高。     

WD615系列柴油机气道的改进

介绍了WD615系列柴油机进排气道的改进目的和改进方案。进气道减小了螺旋角度并对气阀座进行了重新设计,排气道采用了与排气管相匹配的近似圆形截面并进行了光滑过渡。试验结果表明：改进设计后,进气涡流比由原来的2．43下降到1．80,进排气道的流量系数分别提高了24．7％和50％。整机试验证明改进后发动机获得了较理想的综合性能和排放水平。     

Experimental investigation of the performance and exhaust emissions of a swirl chamber diesel engine using JP-8 aviation fuel

An experimental study is conducted to evaluate the use of JP-8 aviation fuel as a full substitute for diesel fuel in a Ricardo E-6 high-speed naturally-aspirated four-stroke experimental engine having a swirl combustion chamber. The study covers a wide range of engine load and speed operating conditions, comprising measurements of cylinder pressure diagrams, high-pressure fuel pipe pressures, exhaust gas temperatures, fuel consumptions, exhaust smokiness and exhaust gas emissions (nitrogen oxides, unburned hydrocarbons and carbon monoxide). Processing of the measurements provides important performance parameters such as maximum combustion pressure, dynamic injection timing, ignition delay, combustion irregularity and knocking tendency. The differences in the measured performance and exhaust emission parameters are determined for engine operation with JP-8 fuel, against baseline engine operation using diesel fuel. The study shows that the exhaust emission levels are not much different for operation with the two fuels. On the contrary, operation with JP-8 fuel increases combustion pressures, combustion intensity and irregularity. This is caused mainly by high pressure fluctuations present in the fuel injection system due to the different physical properties of JP-8 fuel (compared to diesel fuel), which totally change the injection characteristics. Retardation of the static injection timing is one means of improving this situation, while using the same fuel injection equipment. © 1997 John Wiley & Sons, Ltd.     

柴油机故障仿真计算与分析

作者建立了较通用的柴油机故障的仿真模型，开发了柴油机故障仿真软件，并针对柴油机典型故障在不同程度下进行仿真计算及分析，揭示了柴油机故障与热工参数之间的内在联系，为故障诊断提供了参考依据。     

Impact of hydrogen generated by splitting water with nano-silicon and nano-aluminum on diesel engine performance

Efficient utilization of hydrogen generated during the reactions of nano-silicon/water and nano-aluminum/water in internal combustion engine has been investigated in the current work. Engine performance and emission studies of formulated and stabilized nanoemulsion fuels (water in diesel W/D), nano-aluminum in water/diesel (W/DA) and water in nano-silicon/diesel (W/DS) have been compared with those of diesel. Experimental investigations showed reduction in brake specific fuel consumption (BSFC) by 21% and 37%; rise in brake thermal efficiency (BTE) by 16% and 14% when engine was fueled with W/DA and W/DS respectively. For nanoemulsion fuels an increase in induced power was also recorded. Brake mean effective pressure, BTE and NOx emission dropped for W/D due to reduced exhaust gas temperatures. Nevertheless due to elevated peak cylinder pressures and exhaust gas temperatures a marginal rise in NOx, CO, HC and radiative heat emissions was observed with W/DA and W/DS.