船用柴油机综合性能考核体系研究

为科学合理地评估船用柴油机的动力性和经济性,提出了表征柴油机实际工作过程中完成能量转换数量和效率的关键性能指标,深入分析了各项指标的含义及对柴油机整机性能的影响,搭建了综合性能考核体系并针对各项性能指标探究了考核试验方法。提出的考核体系具有较强的科学性和准确性,为船用柴油机综合性能的评估奠定了理论基础。     

电传动履带装甲车辆基本运动性能仿真

随着电传动在履带装甲车辆上的应用越来越广泛,设计了一种轻型电传动履带装甲车辆方案,并提出了其性能指标。为了验证该方案性能指标中的基本运动性能,利用Matlab软件搭建了直流无刷电机控制系统模型,利用Recurdyn软件搭建了车辆的动力学模型,并通过软件接口技术构建了联合仿真模型。然后对原理样车的加速性能、最高速度以及爬坡性能进行了仿真和分析,仿真结果表明:用虚拟样机技术对电传动履带装甲车辆进行建模和仿真是可行的,同时其基本运动性能与提出的性能指标基本一致。     

基于遗传算法的一种串联机构性能指标分析

针对机器人速度同性指标、灵巧度指标和全域性能波动指标的不足,提出一种改进的全域综合性能指标来综合评价机器人的运动性能,该指标可更全面的评价机器人运动学性能.采用单变量分析法,逐个分析了关键部件尺寸变化对这里所述6R串联机构全域综合性能指标的影响规律,得到尺寸变化对其性能的影响趋势.基于改进后的全域综合性能评价指标,利用遗传算法求得了6R串联机构运动性能较好的尺寸.该研究为机器人关键部件尺寸的选取提供了理论依据.     

Delta机器人的尺度综合方法研究

尺度综合是并联机器人运动学设计的最终目标.为此,本文针对Delta机器人提出了一种最优尺度综合方法.首先对机构进行运动学分析得到局部灵活度的性能评价指标,其次将局部性能评价指标综合为全域性能指标,并将尺度综合问题归结为一类参数优化问题.上述方法对这类高速轻型并联机器人以及其它并联机构的运动学设计理论有一定指导意义.     

柴油机机油耗偏高的原因、危害及对策

机油消耗量是柴油机的重要性能指标之一,机油耗偏高会影响整机的排放指标和可靠性.文中论述了我国车用柴油机机油消耗量偏高的主要原因、危害及对策.     

装甲车辆动力性能联合仿真技术研究

以某型装甲车辆为研究对象,基于涡轮增压柴油机工作过程数值模拟理论、多体动力学理论和联合仿真技术,建立了包括动力装置、传动装置、行动装置以及随机路面模型的整车动力性能仿真模型。采用Simulink平台实现了不同软件之间的数据交互与存储,实现了装甲车辆整车动力性能联合仿真。该模型模拟了车辆在实际行驶过程中驾驶员操作和发动机动态工况对整车动力性能的影响,并通过实车实验进行了验证,为装甲车辆动力性能研究提供了一种新方法。     

多层次模糊综合评判法在液压油性能评价中的应用

影响液压油性能的因素很多。包括诸多不可量化的因素。针对目前对液压油性能的评价一般仅局限于对液压油的污染度等理化性能进行评价,提出了利用模糊综合评价法,从液压油的理化性能指标、模拟性指标、性能试验指标3个方面来综合评价液压油性能的新方法。     

某16V柴油机整机性能与试验研究

利用GT-POWER建立16V柴油机热力学计算模型,通过整机台架试验数据对计算模型进行标定验证。在此基础上,开展了整机额定工况下负荷特性计算研究,通过对不同压缩比16、16.5、17、17.5、18及不同供油提前角15°CA、15.5°CA、16°CA、16.5°CA、17°CA工况模拟计算研究其对发动机有效功率、燃油消耗率、排气温度等总体性能指标影响规律。表明当整机压缩比取17.6、供油提前角为16.5°CA～17°CA区间时,常用工况燃油消耗率为204.1g/kWh,柴油机综合性能最佳,为进一步开展整机功率提升及可靠性技术研究提供研究基础。     

基于整机效能匹配的液力变矩器性能评价

为了解决液力变矩器在整机复杂工况下的性能评价问题,提出了一种基于整机载荷特征的液力变矩器评价方法,即建立整机的数字化模型,以传动链效率提升作为目标来评价不同载荷工况下液力变矩器的性能.对比液力变矩器的模型解析结果和台架试验数据,验证了变矩器系统子模型的准确性.选取2种性能相近的变矩器作为评价对象,通过整机系统计算得到它们在典型工况下的输出情况和评价指标,仿真结果表明液力变矩器和整机合理匹配可以有效提高整机效率,对液力变矩器改型和设计有实际意义.     

基于模态灵敏度的柴油机传动箱结构改进设计

传动箱是柴油机上用于包络传动机构的壳类部件,在评价柴油机整机刚度的模态试验过程中,整机的多个低阶模态振型均显示为传动箱局部模态,进而发现传动箱对柴油机整机刚度的影响较大。基于上述实际问题,在利用试验模态法验证传动箱有限元模型有效的基础上,通过对该柴油机传动箱结构进行模态计算,分析了其动态特性,并进一步以传动箱一阶模态的频率和最大模态变形为响应指标,以传动箱宽度等七种主要结构参数为设计变量进行了灵敏度分析,结果表明传动箱壁厚是影响其刚度的关键因素。然后从传动箱壁厚角度提出了10种传动箱结构改进设计方案,并以模态频率和结构质量变化等指标对比分析得到改进方案4(传动箱壁厚增量为0.5mm)为最优设计方案。研究表明:传动箱壁厚参数是影响传动箱结构刚度的关键因素,而传动箱结构刚度对柴油机整机刚度的影响较大,文中将灵敏度分析、模态试验、数值模拟相结合的方法对于类似壳类零件具有一定的借鉴意义。     

船用中速机油使用性能的评定方法

通过对船用中速机油的现有台架进行改造,增加润滑油净化系统,建立了船用中速机油使用性能评定方法。该方法可模拟船舶发动机实际使用情况,考察船用中速机油受水污染后的碱值衰变、分水性能、活塞清净性及抗磨损等实际使用性能。通过对几种船用中速机油的评定试验表明,选择的试验条件合理,该评定方法可以满足评价油品综合性能的要求。     

基于SSA算法优化SVM的发动机润滑油信息状态评估

润滑油信息能够有效反映装甲车辆发动机的健康状态,对车辆发动机状态评估十分重要。以某型装甲车辆发动机为研究对象,提出一种基于麻雀搜索算法(Sparrow Search Algorithm, SSA)优化支持向量机(Support Vector Machine, SVM)的发动机状态评估算法。该算法首先对润滑油原始数据进行去噪及归一化处理,然后使用麻雀搜索算法优化支持向量机的核参数与惩罚参数,最后利用寻优后的参数建立评估模型。实验结果表明,采用麻雀搜索算法优化的支持向量机分类准确率高达96.67%,能够有效对发动机状态进行评估,为装甲车辆发动机的换油以及维修提供依据。     

基于波动法与模糊聚类的柴油机状态监测研究

状态评级是柴油机状态监测的主要目的。常规的以特征参数变化倍数评级的方法对于经常拆迁的设备效果不理想;而模糊C（center）-均值聚类算法不能自动对聚类结果进行等级排序。文中提出的波动法与模糊C-均值聚类相结合的状态评级则有效地解决了上述问题。波动法原理为：柴油机各缸的特征参数波动越小,则整机状态越好。选取与柴油机状态密切相关的7个参数组成特征向量,用现场采集的PZ12V190柴油机的35个样本建立聚类标准;将另10台柴油机与标准逐一再聚类,其结果与实际情况吻合得很好。表明该方法对多缸柴油机状态评级的有效性和实用性。     

The effect of biodiesel and ultra low sulfur diesel fuels on emissions in 11,000 CC heavy-duty diesel engine

It seems very difficult to comply with upcoming stringent emission standards in vehicles To develop low emission engines, better quality of automotive fuels must be achieved Since sulfur contents in diesel fuels are transformed to sulfate—laden particulate matters as a catalyst is applied, it is necessary to provide low sulfur fuels before any Pt-based oxidation catalysts are applied In general, flash point, distillation 90% and cetane index are improved but viscosity can be worse in the process of desulfunzation of diesel fuel Excessive reduction of sulfur may cause to degrade viscosity of fuels and engine performance in fuel injection systems This research focused on the performance of an 11,000 cc diesel engine and emission characteristics by the introduction of ULSD, bio-diesel and a diesel oxidation catalyst, where the bio—diesel was used to improve viscosity of fuels in fuel injection systems as fuel additives or alternative fuels     

Effects of refined palm oil (RPO) fuel on wear of diesel engine components

In this particular research work, the effects of refined palm oil (RPO), as alternative fuel, on wear of diesel engine components are assessed. Fleet testing is carried for the qualifying candidates diesel fuel replacement, i.e. 100% RPO fuel or 50% RPO and 50% conventional diesel fuel mixture. The base line of the fleet testing is using pure conventional petroleum diesel fuel as an energy source in one of the tested vehicles in the fleet. Analysis of used engine lubrication oil, taken when the oil was changed on the vehicles, was compared to the analysis of used oil samples pulled from 100% diesel fuel engines. The finding suggested that the pure RPO and RPO blended fueled engines were wearing at a normal rate.     

基于工艺优化的机油泵结构改进设计

通过对传统柴油机分体叠合式机油泵的结构和工艺进行分析,提出了工艺优化方案,设计了新型整体包容式机油泵,消除了传统机油泵存在的问题,降低了生产成本,提高了柴油机的性能指标。在JD-S195等型柴油机上应用取得了较好的使用效果。     

Quantitative analysis of vehicle particle emission by using calibrated CPC system

Particle size distribution and particle number concentration from diesel engines are subjects of significant environmental concerns especially in the EU. A few years ago, the UN-ECE PMP proposed a method for measuring particle emissions in the diluted exhaust of internal combustion engine vehicles, which has become a key method used in new dilution systems and sampling condition. This paper describes the effects of parameters such as condensation particle counter (CPC) according to test procedures, test fuel and vehicle test mode, including NEDC and CVS-75 mode. The main results obtained from this study can be summarized as follows: (1) Periodic calibration of the CPC system is essential because the long-term usage of a CPC leads to an underestimation in the measurements of small particles. (2) Particle emissions measured by the UN-ECE PMP method were found to exhibit comparable repeatability as compared to other regulated emissions. (3) In particle number concentration emitted from different-fueled vehicles, the sources of particle emissions in an ascending order of magnitude are as follows: DPF equipped diesel passenger vehicles, gasoline and LPG fueled vehicles, and DPF unequipped diesel passenger vehicles. Also, we found that the particle numbers of DPF equipped diesel passenger vehicles, gasoline and LPG-fueled vehicles can meet the EU regulation limit (<6.0×10¹¹#/km), while DPF unequipped diesel passenger vehicles do not meet the EU limit.     

Investigation of the effects of steam injection on the emissions and performance of a diesel engine using waste chicken oil methyl ester

The use of biodiesel-blended fuels in diesel engines improves the engine performance parameters and the partial recovery of incomplete combustion products, while also increasing the level of NOx emissions. In this study; biodiesel obtained through the transesterification of waste chicken frying oil was mixed with diesel fuel (90% diesel + 10% biodiesel-B10), and was then used as fuel in a direct injection diesel engine. To reduce the increased NOx emissions caused by the use of B10 fuel, the steam injection method (which is one of the NOx reduction methods) was applied. Steam was injected into the intake manifold at different ratios (5%-S5, 10%-S10 and 15%-S15) and at the time of the induction stroke with the aid of an electronically controlled system. Based on the study results, it was observed that steam injection into the engine using B10 fuel improved both the engine performance and the exhaust emission parameters. It was determined that the S15 steam injection ratio resulted in the best engine performance and emissions parameters. In comparison to STD fuel; the highest increase observed at the S15 steam injection ratio in the effective engine power was 2.2%, while the highest decrease in the specific fuel consumption was 3.4%, the highest increase in the effective efficiency was 3.5%, and the highest decrease in NOx emissions was 13.7%.

     

Investigation of combustion and emission characteristics of n-hexane and n-hexadecane additives in diesel fuel

One of the most important basic requirements of diesel-powered vehicles that they have lower pollutant emissions and fuel consumption. In diesel engines, combustion and engine performance are influenced by the physical and chemical properties of the used fuel. Engine design studies are not enough to increase engine performance and reduce exhaust emissions alone. By adding fuel additives in diesel fuel, the physical and chemical properties of the fuel can be improved. Fuel additives affect engine performance, combustion and emissions positively by exerting catalyst effect during combustion. In this study, n-hexane and n-hexadecane were added in diesel fuel (D0) by volume of 4, 12 % and 20 %. With respect to D0 fuel, in DHD20 and DHX20 fuels engine torque increased by 1.60 % and 1.32 %, respectively, while the brake specific fuel consumption decreased by 3.12 % and 1.98 %, respectively. Maximum cylinder pressures and heat release rate values of the ingredient added fuels increased. It was seen that NO_x emissions increased while HC, CO and soot emissions decreased with increasing contribution ratio.

     

Performance and combustion characteristics of a diesel engine with titanium oxide coated piston using Pongamia methyl ester

Owing to the increasing cost of petroleum products, fast depletion of fossil fuel, environmental consideration and stringent emission norms, it is necessary to search for alternative fuels for diesel engines. The alternative fuel can be produced from materials available within the country. Though the vegetable oils can be fuelled for diesel engines, their high viscosities and low volatilities have led to the investigation of its various derivatives such as monoesters, known as bio diesel. It is derived from triglycerides (vegetable oil and animal fates) by transesterification process. It is biodegradable and renewable in nature. Biodiesel can be used more efficiently in semi adiabatic engines (Semi LHR), in which the temperature of the combustion chamber is increased by thermal barrier coating on the piston crown. In this study, the piston crown was coated with ceramic material (TiO₂) of about 0.5 mm, by plasma spray method. In this present work, the experiments were carried out with of Pongamia oil methyl (PME) ester and diesel blends (B20 & B100) in a four stroke direct injection diesel engine with and without coated piston at different load conditions. The results revealed 100% bio diesel, an improvement in brake thermal efficiency (BTE) and the brake specific fuel consumption decreased by about 10 % at full load. The exhaust emissions like carbon monoxide (CO) and hydrocarbon (HC) were decreased and the nitrogen oxide (NO) emission increased by 15% with coated engine compared with the uncoated engine with diesel fuel. The peak pressure and heat release rate were increased for the coated engine compared with the standard engine.