Soot reduction has attracted worldwide attention. Ducted fuel injection (DFI) is a newly established strategy that follows the idea of leaner lifted-flame combustion (LLFC), aiming to enhance premixing and reduce soot. A better understanding of spray characteristics of the mixing process is of great significance so that this technology can be fully applied. The study investigated ducted spray with different duct sizes through numerical simulation. Results showed that longer and narrower ducts lead to higher spray velocity due to decreased total gas entrainment-lower gas resistance, and the restriction of radial development of the spray in the near field. Proper duct configuration improves spray atomization in terms of reducing droplet size. The analysis of a special appearance called a "mushroom-shaped" head was also conducted. As the jet penetrates through the duct, shearing vortices form and develop. Under the effect of the pressure difference between the duct inside and outside, the spray tip deformed and diffused radially.

中文翻译：

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不同管道尺寸的管道燃油喷射的数值研究

烟尘减排已引起全世界的关注。管道燃油喷射 (DFI) 是一种新建立的策略，它遵循更稀薄的升焰燃烧 (LLFC) 的理念，旨在加强预混合并减少碳烟。更好地了解混合过程的喷雾特性，对于充分应用该技术具有重要意义。该研究通过数值模拟研究了不同管道尺寸的管道喷雾。结果表明，由于总气体夹带减少 - 气体阻力降低，并且近场喷雾径向发展受到限制，更长和更窄的管道导致更高的喷雾速度。适当的管道配置在减小液滴尺寸方面改善了喷雾雾化。还对称为“蘑菇形”头部的特殊外观进行了分析。当射流穿过管道时，会形成和发展剪切涡流。在管道内外压力差的作用下，喷头发生变形并呈放射状扩散。