缸内直喷汽油机颗粒物粒径分布特性

采用DMS500快速颗粒取样分析仪对一台缸内直喷国Ⅳ汽油机进行了颗粒物粒径分布特性的试验研究．结果表明：缸内直喷汽油机排气颗粒物呈包括核态和积聚态颗粒物的双峰分布，仅怠速工况呈核态单峰分布．随转速升高，总颗粒物数浓度在部分负荷下逐渐降低，外特性先降低后升高；随负荷增加，总颗粒物数浓度在中、低负荷下逐渐降低，满负荷时急剧增加．随转速升高，核态颗粒物在部分负荷速度特性下数密度峰值逐渐降低，外特性下先降低后增加；积聚态颗粒物数密度峰值逐渐降低．随负荷增加，核态颗粒物数密度峰值在中、低负荷时逐渐降低，满负荷时增加；积聚态颗粒物数密度峰值在中、低负荷时先升高后降低，满负荷时最高．

Particle Size Distribution from Gasoline Direct Injection Engine

A DMS500 fast particulate spectrometer was employed to characterize the particle size distribution from a gasoline direct injection （GDI） engine, which meets the regulations of China 1V standards. The results show that exhaust particulates from GDI engine are bimodal in form with nucleation mode particle and accumulation mode par- ticle, except for a unimodal nucleation mode particle which is shown in idle condition. With the increase in engine speed, the total particle number concentration increases gradually under the speed characteristics in part load condi- tion, but decreases after an initial increase in wide open throttle （WOT） condition. With the increase in engine load, the total particle number concentration decreases gradually in part load condition, but increases abruptly in full load condition. The peak value of number density for nucleation mode particle drops gradually under the speed characteris- tics in part load condition, but increases after an initial decrease in WOT condition with the increase in engine speed. The peak value of number density for accumulation mode particle shows a decreasing trend with the increase in engine speed. At the constant speed, the peak value of number density shows a gradually decreasing trend for nucleation mode particle and a dropping trend after an initial increase for accumulation mode particle as the load increases, except for an increasing trend for nucleation mode particle and a peak value for accumulation mode particle in full load condition.