模拟海拔高度对柴油机燃烧影响的可视化试验

在定容燃烧弹内模拟一款重型柴油机喷油时刻的缸内热力学状态,基于高速摄影开展了不同海拔高度下柴油燃烧的可视化试验研究。结果表明,海拔高度对着火延迟、着火距离、升举长度、卷吸空气比率以及火焰亮度等都有显著的影响,海拔从0 m升高到4 500 m时,着火延迟由0.67 ms延长至1.04 ms,着火距离由22.09 mm增大到37.03 mm;升举长度由23.1 mm增大到34.5 mm;卷吸空气比率由12.0%增大到14.0%;空间积分火焰亮度峰值减小,且空间积分火焰亮度峰值的变化幅度和卷吸空气比率的变化幅度都随海拔升高而减小;时间积分火焰亮度减小,碳烟生成总量减少。

Visualization Experiment of Effect of Simulated Altitudes on Diesel Combustion

Experiments of diesel flame propagation and soot formation characteristics at different simulated altitudes were conducted in a constant volume combustion vessel reproducing diesel-like thermodynamic conditions of a heavy-duty diesel engine. The results show that with the increase of altitude from 0 m to 4 500 m, the ignition delay becomes longer from 0.67 ms to 1.04 ms and the ignition distance from 22.09 mm to 37.03 mm. Besides, the lift-off length increases from 23.1 mm to 34.5 mm, making the stoichiometric air ratio increase from 12.0 % to 14.0 %. Moreover, the peak value of spatially integrated natural luminosity decreases, showing the same trend of variation with the stoichiometric air ratio. Furthermore, the time integrated natural luminosity decreases, which implies that the soot formation is reduced.