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排序方式: 共有791条查询结果,搜索用时 15 毫秒
1.
Chenyang Fan Chonglin Song Gang Lv Jiangjun Wei Xuyang Zhang Yuehan Qiao Ye Liu 《Proceedings of the Combustion Institute》2019,37(4):4821-4829
Post injection has significant benefit in the reduction of diesel soot emissions. Therefore, there is a need to understand the effect of post-injection strategy on soot physicochemical properties and reactivity because they play an important role in soot oxidation process that governs the final soot emissions. This work focuses on the impact of post injection on the physicochemical properties and reactivity of diesel in-cylinder soot using a main plus post injection (M*P) and a single injection (M) strategy. The soot was sampled by a developed total cylinder sampling system, and the dividing points of soot formation-dominant and oxidation-dominant phases were used for studying the impacts of post injection on the characteristics of in-cylinder soot. The physicochemical properties of the soot samples, including primary particle size, nanostructure, carbon chemical state and surface functional groups, were characterized. The soot reactivity was evaluated in terms of peak temperature, burnout temperature and apparent activation energy. In the oxidation-dominant phase, the M*P soot initially possesses smaller primary particle size, shorter fringe length, larger tortuosity, lower sp2/sp3 hybridization ratio of carbon atoms and higher content of aliphatic CH groups than the M soot. The beneficial influence of physicochemical properties on soot reactivity when using post injection is validated by the thermogravimetric data, which shows that the M*P soot is more reactive than the M soot at the onset of the oxidation-dominant phase. In the M*P case, the soot generated from the main-injection combustion has lower reactivity than the soot from the post-injection combustion after they experience the soot formation-dominant phase. The results indicate that the use of post injection leads to in-cylinder soot with physicochemical properties that favor reactivity. The enhancement of reactivity means that the soot will be more readily oxidized in the subsequent combustion process, and consequently contributes to a reduction in final soot emissions. 相似文献
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The use of liquid fuels such as kerosene is of interest for the Pulse Detonation Engine (PDE). In this context, a representative
gaseous mixture of the lighter products resulting from the decomposition of a kerosene of type JP-10 was studied. The detonability
limits of simple components (hydrogen, ethylene, propylene) and mixtures of these components were tested in a 50 mm diameter
and 2.5 m long detonation tube. This dimension is compatible with the applications of the aircraft industry and more particularly
the PDE. The influences of the nitrogen dilution, geometry of the DDT device (Schelkin spiral), ignition energy and initial
pressure were investigated.
This paper was based on work that was presented at the 19th International Colloquium on the Dynamics of Explosions and Reactive
Systems, Hakone, Japan, July 27 - August 1, 2003.
Communicated by J.E. Shepherd 相似文献
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Electrical aspects of aircraft jet engine operation are considered. A phenomenon previously observed experimentally, namely, the disappearance of the engine current and alternating electric signal induced by the engine jet in the afterburner regime, is explained. It is shown that this phenomenon results from the detachment of electrons from negative ions when the gas temperature in the afterburner increases. This leads to an increase in the effective conductivity of the gas. As a result, the engine current circuit is closed on the internal duct walls and engine charging becomes insignificant.A physico-mathematical model of the electrical processes in the afterburner is formulated and model problems are solved. 相似文献
7.
内燃机活塞环-缸套摩擦功耗的设计计算方法之研究 总被引:3,自引:0,他引:3
以往在计算内燃机活塞环-缸套摩擦副的摩擦功耗时,只是计算活塞环与缸套之间流体润滑剂的粘性剪应力,这显然不能客观地反映出该摩擦副的润滑状态。实际上,活塞环-缸套间的摩擦力产生于两个方面,一是粘性流体的剪应力,二是摩擦界面相互接触峰元的剪切作用。然而截至目前,针对这两方面进行全面分析研究的报道却还很少,因此,为了给低摩擦功耗环组的设计提供科学依据,基于对活塞环在运动过程中润滑状态的分析,提出了一种适用于不同类型内燃机设计计算的活塞环-缸套摩擦功耗的计算方法,并以其对现有结构的S195柴油机活塞环-缸套摩擦副的摩擦功耗进行了计算,同时还对影响摩擦功耗的因素作了考察与讨论,利用台架试验测量油膜厚度的方法对这种算法进行试验验证的研究结果表明,理论值与实测值吻合得很好。 相似文献
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确定计算模型时,发动机定子按实际刚度,采用NASTRAN70.0程序对发动机整机进行了动力分析,分析结果与试验进行了比较,吻合度优于美国GE公司计算结果。作者认为造成偏磨故障的原因是弹性环压死,使压气机转子与定子反向平动的第六阶临界转速上升到接近放气阀门关闭时转速所致。根据动力响应计算结果,装配工艺采取措施后,克服了此偏磨故障。 相似文献
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一种摩擦学状态在线监测系统的研究 总被引:2,自引:5,他引:2
研制了一种用于船用柴油机的摩擦学状态在线监测系统。它集磨粒监测,润滑油质量监测,柴油机扭矩及时转速监测于一体,利用在线铁谱技术监测润滑油中的铁磁性磨粒,利用容栅型电容传感器在线监测污染物引起的润滑油介电常数的变化,利用光电传感器和随轴转动齿盘产生的脉冲及相位差在线测量柴油机输出轴的扭矩及瞬时转速。此外,该监测系统还可将柴油机的磨损状态与动力状态相关联,监测由于各缸爆排压力变化造成的瞬时转速变化,从 相似文献
10.
三维相移电子散斑干涉法在柴油机机身中的应用 总被引:10,自引:2,他引:10
本文通过一新的三维电子散斑干涉方法,结合四步相移技术和图象处理技术,从三幅全场散斑位相条纹图分离出独立的u、υ、w场位移。测量系统的特点是用三个激光器作为光源,一个PZT相移器推动三个反射镜产生参考光并实现相移以及CCD摄像机前放置大错位剪切镜。将该测量系统应用到柴油机机身部件测量上,得到了机身主轴承孔周的三维位移场,并将此结果作为有限元计算的边界条件,得到了精确的柴油机机身计算结果,证明这一新技术可为柴油机零部件的强度和刚度分析评价提供一种十分有效的方法。 相似文献