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本文利用模拟在过热状态下的燃油中气泡生成理论与传统的燃油喷雾贯穿距离计算相结合,对闪急沸腾喷雾的贯穿距离和锥角进行了数值计算,以期为进一步研究闪急沸腾喷雾提供帮助。 相似文献
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闪急沸腾喷雾规律的试验研究 总被引:3,自引:0,他引:3
本文通过采用特殊的高温、高压喷雾罐,可从三个垂直方向的石英玻璃窗口,用高速摄影记录喷雾发展的全过程,探索了各种不同燃料和在不同条件下对闪急沸腾喷雾规律的影响,并在实机做了试验。 相似文献
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闪急沸腾喷雾场粒度分布特性的研究 总被引:1,自引:0,他引:1
用激光全息术测量了闪急沸腾喷雾场的粒度分布,并与常温雾场粒度分布进行了比较。结果表明,闪急沸腾喷雾场的粒度分布具有喷雾粒子直径小,喷注的轴向径向粒子分布均匀等特点。 相似文献
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Numerical simulations have been carried out to investigate the liquid atomization and spray process using the Discrete Phase
Model of the commercial CFD code combined with the Wall-Film boundary conditions. The effects of spray parameters on droplets
Sauter mean diameter (SMD), droplet collision speed, the thickness of liquid-film, the surface temperature and its uniformity
were analyzed in the present study. The simulation results and the experimental data obtained in the available literature
agree within 13.8%. The computational results show that the spray pressure is the main factor to realize the atomization.
Increasing the mass flux and the spray pressure, the droplet collision speed increases while the corresponding maximum film
thickness on the heated surface declines. The surface temperature changes indistinctively with the increase of the spray distance,
but the temperature distribution tends to be uniform. 相似文献
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柴油机多阶雾化模型及动态喷雾模拟 总被引:2,自引:0,他引:2
本文在作者推导的有粘液柱3维不稳定弥散关系式的基础上,对柴油机喷注的雾化机理进行了分析,建立了燃油雾化的多阶不稳定模型,根据不稳定流的最大波幅增长点提出了初始雾化参数(如滴径及滴径分布,喷雾锥角)的具体算法,并考虑了液滴的2次雾化问题。以半波正弦喷油规律为例的动态喷雾模拟表明,本文的计算对蒸发量有明显的改进,从而有助于解决原KIVA计算中蒸发量不足的问题,更重要的是,初始雾化模型的建立把多维模型中缸内工作过程与缸外供油过程密切联系起来,有利于分析喷油系统对喷雾混合过程的影响。 相似文献
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直喷式发动机喷雾模型研究进展 总被引:3,自引:0,他引:3
雾化是在点火之前喷射燃油与环境因素发生复杂的物理作用的结果。本文从雾化过程喷嘴内流动、射流破裂、油团破裂、油滴蒸发四个阶段着手,在考虑到雾化过程中所伴随的减速、变形、扩散、缸壁油膜形成、油滴之间碰撞以及油滴与缸壁碰撞等物理现象基础上,综合对比了国际上近年来用实验分析方法所建立的各种相应计算模型的特点、应用情况及不足。分析了选择子模型组合并集成在计算模型(KIVA)中对缸内喷射对象的雾化过程模拟的可行性。最后结合计算机技术的发展指出了雾化过程模拟发展趋势。 相似文献
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This paper has focused on the droplets behavior of kerosene RP-3 spray produced by a pressure swirl atomizers in terms of spray pattern, droplet size spatial distribution, mean droplet size, and distribution index with variations of pressure differential. The analyses have been carried out experimentally with the aid of optical diagnostic methods. The spray pattern, such as spray cone angle and fuel spatial distribution, has been measured by the technique of planar laser induced fluorescence of kerosene. A method for correction of fuel distribution measurement error induced by laser attenuation in spray is proposed and validated. The droplet size spatial distribution in central axis plane of the spray has been measured by a planar droplet sizing method which combining laser induced fluorescence and Mie scattering. The spray pattern in axial center plane and cross-sectional plane perpendicular to axis of the atomizer indicate that the droplets in spray concentrate around the outer periphery and in a narrow annular zone at the near-field of fuel injector exit, and then disperse to produce a solid spray at downstream of the spray. The analyses of droplet size spatial distribution, Sauter mean diameter, and distribution index with pressure differential clearly show the presence of droplets collision and its adverse effects on droplet size uniformity. The spray outline, droplet mass spatial distribution, and droplet size spatial distribution, droplets dispersion and collision in the process of atomization provide a great insight into the processes of atomization and spray development, which are key information for fuel injector design and quality control. The visualizations of spray pattern and droplet size spatial distribution with variations of pressure differential for pressure swirl atomizer are key issues in swirl cup or internally staged airblast fuel injectors because pressure swirl atomizer provides primary atomization or pilot spray which affects the quality of air/fuel mixing in lean-burn combustion. Moreover, a well-defined and complete database regarding the isothermal hollow cone spray is provided for validation of spray model. 相似文献
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燃油喷雾雾化特性直接影响燃烧,从而也极大地影响了柴油机的各项性能,而喷嘴在很大程度上决定了燃油的喷雾雾化特性。本文基于现有研究文献,介绍了簇孔式喷油嘴的概念及其喷雾雾化特性,通过与传统单孔喷嘴的比较实验,阐述了簇孔式喷嘴的在喷雾贯穿距离,喷雾锥角,雾化能力等喷雾特性上的独特优势。这一新型喷嘴的提出与应用,对改善喷雾雾化与燃烧,提高发动机性能具有重大意义。 相似文献
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本主要研究燃油喷入气体中的雾化过程。在假设雾化是由于气液之间气动相互作用导致液体射流表面不稳定波增长并最终导致细小液滴形成的基础上,把燃油雾化过程分为两个阶段:1次雾化和2次雾化。前只发生在气液交界面上,主要由不稳定波增长和破碎所引起;后则发生在气液渗混区,受1次雾化后形成的液滴在气体中进一步破碎和聚合控制。章最后分析了某些参数对雾化的影响,并把计算得到的喷雾贯穿距离和SMD同实验进行了比 相似文献
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采用大涡模拟方法和不同的雾化模型对定容弹中燃油喷射和雾化过程进行数值分析.着重探讨亚网格尺度湍动能,特别是燃油喷雾所诱导的亚网格湍能源项对液滴运动和喷雾特性的影响,并进一步探讨了亚网格气相湍动能对液滴弥散速度乃至喷雾场的影响.通过对不同的工况条件的模拟计算对喷雾的影响因素进行了讨论并与相关的实验进行了比较.计算结果表明,KH-RT破碎模型要优于MTAB模型,湍流弥散效应和亚网格湍动能喷雾源项对燃油喷雾有着重要的影响,其作用均是减少喷雾贯穿距,使模拟结果更接近于实验.其中,湍流弥散效应的影响更为显著. 相似文献
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In this study, we investigate the spray behavior and atomization characteristics of refrigerant R22 injection in a high pressure chamber under various ambient pressures using a spray visualization system and image processing. In order to observe the spray behavior of R22, the spray images were analyzed in time series after the start of injection. From the spray images, spray characteristics such as the spray tip penetration, cone angle and spray area were investigated by using the contour map of the light intensity levels. The results showed that the ambient pressure significantly affected the spray characteristics of the refrigerant. The spray tip penetration velocity was the highest at the ambient pressure of 500 kPa. When the ambient pressure was lower than 500 kPa, the vaporization of the refrigerant determined the spray and atomization characteristics; however, when ambient pressure was higher than 500 kPa, the surface tension and viscosity of the refrigerant and the density of ambient gas affected the spray behavior and atomization characteristics. Furthermore, the injection stream of the refrigerant was compared with the injection stream of water at the ambient pressure of 1500 kPa. 相似文献
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溶气对不同燃油喷雾特性的影响 总被引:1,自引:0,他引:1
对溶有甲烷(CH4)的煤油和柴油稳态喷雾特性进行了试验研究,并对两者的试验结果进行了对比分析。结果表明,溶气对燃油的雾化有正反两方面的影响,它与CH4的浓度、喷嘴的L/D值、燃油的性质有关;柴油和煤油试验结果的规律相似,但促进雾化的临界浓度值不同;由于溶气的膨胀作用,在喷嘴出口处形成均匀的喷雾,喷雾锥角急剧增大;CH4的浓度较大时,燃油雾化粒子分布规律向小粒径方向移动,浓度较小时,向大粒径方向移动;低粘度的燃油有助于增强溶气对燃油雾化的促进作用。 相似文献