In-nozzle flash boiling flow of multi-component fuel and its effect on near-nozzle spray
In-nozzle flash boiling flow of multi-component fuel and its effect on near-nozzle spray
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DOI：
10.1016/j.fuel.2019.04.104
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发表时间：
2019-09
期刊：
影响因子：
7.4
通讯作者：
Shangze Yang;Xuesong Li;D. Hung;M. Arai;Min Xu
中科院分区：
文献类型：
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作者：
Shangze Yang;Xuesong Li;D. Hung;M. Arai;Min Xu
与单组分燃料喷雾相比，多组分燃料喷雾的雾化和蒸发过程更为复杂，这是因为燃料组分之间的物理性质不同。当燃油喷雾是在闪急沸腾条件下形成时，这种复杂性更加明显。因此，多组分燃料的雾化和蒸发研究已成为近年来的一个实用研究热点。然而，由于缺乏相关的实验和理论解释，闪急沸腾条件下的喷雾形成还没有完全被揭示。为了应对这些挑战，本研究集中于对多组分闪急沸腾喷雾现象的高速光学研究。测试流体是由三种组分(正戊烷、异辛烷和正庚烷)组成的汽油替代燃料。为了进行光学研究，制作了一种放大的透明二维喷嘴。用相位多普勒干涉法(PDI)测量了液滴直径。实验结果表明，掺入高挥发分燃料和低挥发分燃料可以显著增强喷管内部流动(喷管内流)中闪蒸气泡的产生。同时，闪蒸气泡的增加可以促进燃油在喷嘴附近的破碎，使得燃油液滴的SMD更小，分布更均匀。此外，适当的高挥发分燃料和低挥发分燃料的混合比例可以缓和喷嘴内部的层状结构(气泡和液体流动)，从而稳定从液体韧带到燃料喷雾的破碎过程，而喷雾几何形状的变化很小。
In comparison with single-component fuel spray, the atomization and evaporation of multi-component fuel spray is more complex due to the physical property difference among the fuel components. This complexity is more significant when the fuel spray is formed under flash boiling condition. Therefore, the investigation of atomization and evaporation of multi-component fuel has recently become a practical research focus. However, due to the lack of related experiments and theoretical explanations, the spray formation under flash boiling condition has yet to be fully revealed. To address such challenges, this study is focused on high-speed optical investigation of multi-component flash boiling spray phenomena. Test fluids were gasoline surrogate fuels composed of three components (n-pentane,iso-octane, and n-decane). A scaled-up transparent two-dimensional nozzle was fabricated for the optical investigation. The droplet diameter was also measured using Phase Doppler Interferometry (PDI). Experimental results show that mixing of high volatility fuel with low volatility fuel can significantly enhance the generation of flash-boiling bubbles in the internal flow inside the nozzle (in-nozzle flow). Meanwhile, the increase of flash boiling bubbles can promote fuel breakup in the near-nozzle region, resulting in fuel droplets of smaller SMD with more uniform distributions. Besides, proper mixing ratio of high volatility fuel and low volatility fuel can moderate the layered structure (bubble and liquid flows) inside the nozzle and therefore can stabilize the breakup process from liquid ligaments into fuel spray with low variation of spray geometry.