中文摘要：

在一台改造的自然吸气高速柴油发动机上使用超低硫柴油／甲醇组合燃烧方式进行台架试验，利用电控单元控制的喷射器向进气道喷射甲醇，与空气形成预混合气后由柴油引燃。在稳态工况下，喷射的甲醇承担的负荷率为10％、20％和30％的情况下，研究了发动机烟度、微粒排放质量浓度和粒径为15～750nm的总数量浓度及其粒径分布特性。试验结果表明，在同一负荷替代率下，随着负荷的增加，柴油质量流量替代率增大；在同一工况下，随着甲醇量的增加，发动机烟度、微粒质量和数量浓度都成近似比例减少；在中低负荷时，甲醇的加入，微粒数量浓度的峰值明显减少，在大负荷时，减少的趋势不太明显；超细微粒数都有所增加，纳米级微粒数的增多可能对人体健康影响更大。

英文摘要：

The study was performed on a 4-cylinder naturally aspirated modified diesel engine using the diesel/methanol compound combustion system. Methanol was induced into the intake manifold with four injectors controlled by an electrically controlled unit （ECU） and mixed with fresh air to form the homogeneous mixtures ignited by pilot diesel. The injected methanol was responsible to 10%, 20% and 30% of power output under different engine operating conditions. The effects of methanol addition on smoke opacity, particulate matter （PM） mass and number concentrations and size distribution characteristics were studied under different amounts of diesel and methanol. The results show that, for the same power substitution by methanol, diesel displalement ratio increase with the increase of load. Under the same operation condition, the smoke opacity, PM mass and number concentrations decrease with the increase of methanol. Under low and medium loads, the PM number concentration decreases largely when methanol is injected. However, there is a slight reduction in PM at the high load, but the number of ultra-fine particulate increases correspondingly, and this may cause the possible serious impact on human health.