科研之友
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摘要
Hydrodynamic characteristics of fuel sprays have significant effect on the pollutant emissions of internal combustion engines. Fuel spray penetration length and spray cone angle are two important criteria in spray quality assessment. Injector geometry has undeniable impact on spray behavior. In this study at first two different cylindrical and conical shape of nozzle hole have been considered from mini-sac kind and their internal liquid flow and the behavior of their resulted sprays have been investigated numerically via AVL-Fire CFD code. Numerical results of the first part of this study show, although using conical nozzles leads to longer spray penetration length, but a decrease in spray cone angle is detected. Furthermore, the results show that Sauter-mean diameter of these two nozzles are almost the same. In the next step in an attempt for having a liquid spray with a much larger cone angle, a conical nozzle with a spiral rifling like guide is proposed and the liquid flow in its inside and the resulted spray behavior are investigated numerically. The numerical results of the second part of this study show that the liquid spray resulted from the new proposed nozzle have surprisingly large cone angle about two fold more than the cone angle of sprays of two previous cases. In addition numerical results show that in the case of the new proposed nozzle the resulted liquid spray and its droplets have vortical motion. Although in the case of the new proposed nozzle, the penetration length of the liquid spray is shorter than two previous cases, having much larger spray cone angle convinces us that the new proposed nozzle could lead to better mixing of air and fuel droplets and consequently could lead to less pollutant emissions. Most importantly, the penetration length and cone angle of the spray and its vortical motion can be controlled by the geometrical parameters of the new proposed Nozzle.
- 出版日期2017-5-15
