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从理论上分析柴油压力雾化及高压静电辅助雾化的机理,设计实验装置,并采用高级数码相机拍摄柴油在电荷前后不同压力下的雾化照片,通过照片分析静电辅助复合雾化的过程,得出的结论是:柴油在压力作用下通过喷气孔的气化扰动和荷电前后液滴电荷间的相互排斥,形成了复杂的复合雾化过程,使柴油液滴迅速破碎成更小的颗粒,雾化效果更好. 相似文献
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《机械设计与制造》2017,(9)
为深入研究不同比例调合生物柴油对发动机燃烧特性及颗粒物组分的影响,在一台单缸四冲程发动机上进行了调合生物柴油燃烧及颗粒物排放的试验研究。利用燃烧分析仪研究调合生物柴油对发动机燃烧过程的影响,利用热重分析仪(TGA)、气相色谱/质谱联用仪(GC-MS)研究调合生物柴油对颗粒物热重特性、挥发性有机物(VOCs)质量分数及有机可溶成分(SOF)和多环芳香烃(PAHs)组分的影响规律。研究表明:随着生物柴油掺混比的增加,发动机最高爆发压力及压力升高率峰值增加,压力曲线前移,预混放热率峰值随生物柴油掺混比增加而减小。与B0相比,燃用B20调合生物柴油,最高爆发压力增加了5.59%,对应的曲轴转角提前了3°CA。燃用调合生物柴油后VOCs及SOF组分略有增加,燃用B0、B5、B10及B20后颗粒物中VOCs组分的质量分数分别为12.28%、15.09%、23.06%和26.94%,SOF组分的质量分数分别为29.32%、32.08%、34.26%和35.67%,燃用B20后排放颗粒物中总PAHs降低了10.26%。 相似文献
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本试验通过对燃烧生物柴油对发动机排放污染物的测量和分析,探讨了生物柴油降低柴油机排气污染物的机理。研究结果表明:在同一稳定工况下,随着生物柴油加柴油中入比例的上升,燃烧排放物中的CO和HC比柴油排放呈现线性下降,NOx排放有所上升,而CO2排放一本在同一水平。 相似文献
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对不同来源的生物柴油、车用柴油及其生物柴油调合燃料的润滑性能及影响因素采用高频往复试验机法(HFRR)进行研究,认为不同原料的生物柴油其调合柴油燃料的润滑性能存在差异;生物柴油的精制深度会减弱调合柴油燃料的润滑性能;生物柴油体积分数大于20%的调合燃料其润滑性基本与纯生物柴油达到一致;生物柴油体积分数为5%的调合燃料中超标的水含量会降低其润滑性能,但幅度不大,其润滑性主要由5%的生物柴油决定,抗氧、防锈剂、流动改进剂不影响润滑性能;与车用柴油不同,生物柴油调合燃料的运动黏度与磨斑直径没有很好的对应关系。 相似文献
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高压水除鳞喷嘴的分析 总被引:9,自引:1,他引:9
在高压水除鳞系统中喷嘴的喷射冲击力的大小及布置是否合理直接影响除鳞效果,因此,在选取喷嘴时要综合考虑影响喷射冲击力的各要素,使冲击力得到最大,并且在安装时确保各射流相互不干扰,抵消,使系统功能发挥最佳 相似文献
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Raul Payri F. J. Salvador J. Gimeno V. Soare 《Journal of Mechanical Science and Technology》2005,19(11):2040-2052
The present paper centers on the establishment of a quantified relationship between the macroscopic visual parameters of a
Diesel spray and its most influential factors. The factors considered are the ambient gas density, as an external condition
relative to the injection system, and nozzle hole diameter and injection pressure as internal ones. The main purpose of this
work is to validate and extend the different correlations available in the literature to the present state of the Diesel engine,
i.e. high injection pressure, small nozzle holes, severe cavitating conditions, etc. Five mono-orifice, axi-symmetrical nozzles
with different diameters have been studied in two different test rigs from which one can reproduce solely the real engine
in-cylinder air density, and the other, both the density and the pressure. A parametric study was carried out and it enabled
the spray tip penetration to be expressed as a function of nozzle hole diameter, injection pressure and environment gas density.
The temporal synchronization of the penetration and injection rate data revealed a possible explanation for the discontinuity
observed as well by other authors in the spray’s penetration law. The experimental results obtained from both test rigs have
shown good agreement with the theoretical analysis. There have been observed small but consistent differences between the
two test rigs regarding the spray penetration and cone angle, and thus an analysis of the possible causes for these differences
has also been included. 相似文献
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The common-rail injection systems, as a new diesel injection system for passenger car, have more degrees of freedom in controlling
both the injection timing and injection rate with the high pressure. In this study, a piezo-driven injector was applied to
a high pressure common-rail type fuel injection system for the control capability of the high pressure injector’s needle and
firstly examined the piezo-electric characteristics of a piezo-driven injector. Also in order to analyze the effect of injector’s
needle response driven by different driving method on the injection, we investigated the diesel spray characteristics in a
constant volume chamber pressurized by nitrogen gas for two injectors, a solenoid-driven injector and a piezo-driven injector,
both equipped with the same injection nozzle with sac type and 5-injection hole. The experimental method for spray visualization
was based on back-light photography technique by utilizing a high speed framing camera. The macroscopic spray propagation
was geometrically measured and characterized in term of the spray tip penetration, spray cone angle and spray tip speed. For
the evaluation of the needle response of the above two injectors, we indirectly estimated the needle’s behavior with an accelerometer
and injection rate measurement employing Bosch’s method was conducted. The experimental results show that the spray tip penetrations
of piezodriven injector were longer, on the whole, than that of the solenoid-driven injector. Besides we found that the piezo-driven
injector have a higher injection flow rate by a fast needle response and it was possible to control the injection rate slope
in piezo-driven injector by altering the induced current. 相似文献
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This study examines the influence of geometry on the internal flow and macroscopic behavior of the spray in Diesel nozzles.
For this investigation, two bi-orifice nozzles were employed : one cylindrical and one conical. The first step is to use a
non-destructive characterization method which is based on the production of silicone moulds so that the precise internal geometry
of the two nozzles can be measured. At this stage the nozzles have been characterized dimensionally and therefore the internal
flow can be studied using CFD calculations. The results gained from this experiment make it possible also to ascertain the
critical cavitation conditions. Once the critical cavitation conditions have been identified, the macroscopic parameters of
the spray can be studied in both cavitating and non-cavitating conditions using a test rig pressurized with nitrogen and with
the help of a image acquisition system and image processing software. Consequently, research can be carried out to determine
the influence that cavitation has on macroscopic spray behavior. From the point of view of the spray macroscopic behavior,
the main conclusion of the paper is that cavitation leads to an increment of the spray cone angle. On the other hand, from
the point of view of the internal flow, the hole outlet velocity increases when cavitation appears. This phenomenon can be
explained by the reduction in the cross section of the liquid phase in the outlet section of the hole. 相似文献
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在蜂窝陶瓷载体上均匀地喷涂催化剂材料是汽车尾气转化器生产的关键工序.“PC PLC“模式设计的集散控制系统适用于多台喷涂设备的控制.文章介绍了集散系统的特点,描述了基于PLC的喷涂设备控制系统的组成和功能.项目的研究,为汽车尾气净化器生产厂提供了一个高性能、低成本、全自动的解决方案. 相似文献
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针对双路离心喷嘴开展雾化锥角的研究,采用高速摄影仪拍摄不同供油压差,仅副油路、主油路和主副油路同时工作时的喷雾形态,进而分析不同工况下雾化锥角的变化规律,同时与传统经验关系式结果进行对比。结果表明,单路压差增加时,平口式的主油路锥角迅速增大,扩口式的副油路锥角逐渐减小,共同喷射时,由于低压核心区的作用双路锥角处于两路单独喷射之间,并随主油路压差增大而增大,随副油路压差增大而减小。最后将传统经验关系式结果和试验结果进行对比,由于特殊的喷口结构产生了径向速度分量,关系式结果均偏高。 相似文献
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基于作业质量成本的质量改进决策模型研究 总被引:5,自引:1,他引:5
根据质量改进的经济特性,提出了应用质量成本可以为质量改进决策提供有效依据的观点,论证了传统的质量成本分析具有狭隘且针对性不强的缺点。基于过程的思想,综合考察产品的实现过程,提出了“基于作业的质量活动链”的概念,并在此基础上建立了作业质量成本管理体系。论述了各项活动发生的质量成本是相互影响的,要从全局的角度系统地对质量成本进行分析。研究了一种基于作业质量成本的,主要由质量成本数据库、质量改进决策支持系统、预测系统组成的质量改进决策模型,为基于作业质量成本分析的质量目标优化、质量改进方案设计提供了方法。 相似文献
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