单孔主动预燃室火焰射流机理研究

Mechanism of Flame Jet in a Single-Hole Active Pre-chamber

基于单孔主动预燃室,研究了火焰射流的形成机理。在圆形自由紊动射流理论的基础上,提出了单孔主动预燃室点火的火焰射流贯穿距随时间变化的经验公式。该经验公式可以通过射流锥角、预燃室喷口直径和射流在预燃室喷口处的初速度预测射流贯穿距。通过主动预燃室的定容燃烧弹试验和CONVERGE仿真验证,该经验公式所预测的射流贯穿距和反向求得的射流初速度与实测值吻合,最大相对误差分别为6.92%和5.82%。认为此公式能够正确预测单喷孔主动预燃室的射流贯穿距,对于优化预燃室结构以实现更高效地点火,继而提升内燃机的理论热效率具有参考意义。

In this paper the formation mechanism of flame jet is studied based on a single-hole active prechamber.An empirical formula for the variation of penetration distance of the flame jet ignited in the prechamber with respect to time is presented based on the theory of circular free turbulent jet.The jet penetration distance can be predicted corresponding to the jet cone angle,the nozzle diameter and the initial velocity of the jet at the pre-chamber nozzle.The calculated values of jet penetration distance and the initial velocity of the jet at the nozzle are consistent with the experimental values measured in the constant volume combustion vessel experiment of the active pre-chamber.The maximum relative errors are 6.92%and 5.82%respectively.Therefore the proposed formula can correctly predict the jet penetration distance of the singlenozzle active pre-chamber,which has a significance for optimizing the structure of pre-chamber to achieve more efficient ignition and subsequently improving the theoretical thermal efficiency of internal combustion engines.