The spray developments are mostly influenced by the flow characteristics inside a diesel nozzle orifice. In this paper, an experimental visual system is installed with transparent nozzles. This test rig is used to scrutinize the effect of enlarged scales and continuous bubbles on the cavitation phenomena in CI nozzles. The variation of discharge coefficient with the cavitation number under two cavitation patterns and the scale effect of string cavitation on discharge coefficient under three enlarged scales are also explored. Besides, the spatial distribution of standard deviations of the two cavitation patterns is compared and analyzed. Under different enlarged scales, the results indicate that the development stage of string cavitation with two-phase flow is almost the same, and both have similar behavior through the transitional period from single-phase flow stage to complete cavitation development stage. Compared to the situation without bubbles, the cavitation intensity and spray cone angle are promoted. Furthermore, the effect of continuous bubbles is studied under the working condition of a single injection, and the results illustrate that the string cavitation is very sensitive to the bubble content. The findings also display that applying continuous bubbles leads to an enhancement in the cavitation inception and its effect on the geometry-induced cavitation is less than that of string cavitation, under the same conditions.

中文翻译：

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扩大的水垢和连续气泡对柴油机喷嘴气蚀模式的影响

喷雾的发展主要受柴油喷嘴孔内流动特性的影响。在本文中，安装了带有透明喷嘴的实验视觉系统。该测试设备用于检查放大的水垢和连续气泡对CI喷嘴中气穴现象的影响。还探讨了在两种空化模式下，空化系数随空化次数的变化，以及在三个放大比例下串状空化对流量系数的比例效应。此外，比较和分析了两种空化模式的标准偏差的空间分布。结果表明，在不同的放大比例下，两相流串空化的发展阶段几乎相同，从单相流动阶段到完全空化发展阶段的过渡时期，两者的行为相似。与没有气泡的情况相比，提高了空化强度和喷雾锥角。此外，在单次进样的工作条件下研究了连续气泡的影响，结果表明，串空化对气泡含量非常敏感。研究结果还表明，在相同条件下，施加连续气泡可增强空化开始，并且其对几何形状引起的空化的影响小于弦线空化的影响。在单次注入的工作条件下研究了连续气泡的影响，结果表明，串空化对气泡含量非常敏感。研究结果还表明，在相同条件下，施加连续气泡可增强空化开始，并且其对几何形状引起的空化的影响小于弦线空化的影响。在单次注入的工作条件下研究了连续气泡的影响，结果表明，串空化对气泡含量非常敏感。研究结果还表明，在相同条件下，施加连续气泡会导致空化开始，并且其对几何形状引起的空化的影响小于弦线空化的影响。