Abstract In this study, the effect of nozzle inlet rounding on diesel spray formation and combustion is investigated. In order to take into account nozzle geometry, two different nozzle geometries (sharp inlet and rounded inlet) were used in the experiments. Diesel spray injected into a constant volume combustion chamber was modeled by using KIVA3V R2 code. One dimensional nozzle flow model was used in numerical simulations. This model calculates nozzle discharge coefficient and updates the initial droplet radius and droplet velocities according to nozzle inlet geometry. Diesel fuel is represented by diesel oil surrogate mechanism which consists of 71 species and 323 reactions. The numerical spray results were validated with macroscopic spray characterization data obtained by constant volume experiments. Results showed that inlet rounding increases discharge coefficient. At high ambient pressure conditions, sharp and rounded nozzles have similar spray internal structure. However, it is observed that sharp inlet nozzle produces smaller droplets that shorten spray tip penetration and autoignition delay period due to low discharge coefficient. Comparing spray combustion of rounded and sharp inlet nozzles, it is showed that rounded inlet nozzle has lower combustion temperature, less NO and soot concentration than sharp inlet nozzle.

中文翻译：

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喷嘴入口倒圆对柴油喷雾形成和燃烧的影响研究

摘要 在这项研究中，研究了喷嘴入口圆角对柴油喷雾形成和燃烧的影响。为了考虑喷嘴几何形状，在实验中使用了两种不同的喷嘴几何形状（尖锐入口和圆形入口）。通过使用 KIVA3V R2 代码对喷射到定容燃烧室的柴油喷雾进行建模。一维喷嘴流动模型用于数值模拟。该模型计算喷嘴排放系数并根据喷嘴入口几何形状更新初始液滴半径和液滴速度。柴油燃料以柴油替代机制为代表，由 71 个物种和 323 个反应组成。数值喷雾结果通过恒定体积实验获得的宏观喷雾表征数据进行验证。结果表明，入口圆角增加了流量系数。在高环境压力条件下，尖锐和圆形的喷嘴具有相似的喷雾内部结构。然而，据观察，尖锐的入口喷嘴会产生较小的液滴，由于排放系数低，从而缩短了喷嘴穿透和自燃延迟时间。对比圆角和尖头喷嘴的喷雾燃烧，表明圆角入口喷嘴比尖头喷嘴燃烧温度低，NO和烟尘浓度低。