【摘 要】
：
The performance of spark-ignition direct-injection gasoline engines can be influenced by the interactions between fuel spray and in-cylinder air charge characteristics.A highly atomized spray promotes
【机 构】
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School of Mechanical Engineering,Shanghai Jiao Tong University,National Engineering Laboratory of El
【出 处】
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13th International Conference on Liquid Atomization and Spra
论文部分内容阅读
The performance of spark-ignition direct-injection gasoline engines can be influenced by the interactions between fuel spray and in-cylinder air charge characteristics.A highly atomized spray promotes the fuel evaporation in engine cylinder which contributes to higher efficiency and lower exhaust emission.Specifically,higher fuel temperature enhances the fuel spray evaporation due to the superheat phenomenon even at low injection pressure.In this study,for a better understanding of the primary breakup process of superheated sprays,both internal flow and near-field liquid fuel jet of a two-dimensional transparent nozzle are investigated and correlated using high-speed backlit imaging technique.The two-dimensional nozzle is designed for studying the innozzle flow and the near-field jet,allowing clear visualization of individual bubbles inside the nozzle without bubble overlapping.Both ambient pressure and fuel temperature are varied to reach a wide range of superheat conditions.Experimental results show that the bubbles occurring near the nozzle exit affect the shape and dynamic behavior of the near-field jet.The bubble volume fraction can be correlated well with the width of the near-field jet.It shows that higher fuel temperature and lower back pressure increase the inner bubble size and volume fraction.The width of the liquid core of near-field jet decreases with increasing inner bubble volume fraction.Finally,the breakup mechanism of superheated jet can be elucidated with more fundamental understanding of bubble behavior inside the nozzle due to the superheat which causes the exiting liquid jet to form,oscillate,and break up.
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