To investigate the effects of injection timing on particulate emission characteristics for T-GDI(turbo-charged gasoline direct injection)Engine,the experiment was conducted on a T-GDI engine when fueled with M0, M10,M15 and M20 (the methanol/gasoline blends with methanol fraction of 0%,10%,15% and 20% in vol-ume),and different injection timing,respectively. The results show that all of the particle number spectrum curves behave a bimodal distribution, and the nuclear mode peaks locate 23.71 ~27.38 nm, the accumulation mode peaks locate 64.94 ~86.6 nm. And the particle number concentration has the same change with the peaks of curves,that is,as the injection timing delays,they gradually decrease,and then increase,and the engine has the minimum particulate emission at the SOI of 80°CA ATDC, when the methanol proportion increase, they gradually increase,and then decrease,and the M15's particulate emission is the most;when fueled with M0,the engine has the most particulate emission at the SOI of 40°CA ATDC,when fueled with methanol/gasoline blends, the engine has the most particulate emission at the SOI of 100°CA ATDC;the surface area spectrum curves behaves a unimod-al distribution,the peaks of which mainly centered within the range of 20.54 ~31.62 nm, and the surface area concentration has the same change with the particle number concentration,but more apparently.%为研究增压直喷甲醇汽油机在不同喷油时刻下的微粒排放特性,在一台增压直喷汽油机上进行了不同喷油时刻下燃用M0、M10、M15和M20(甲醇体积分数分别为0%、10%、15%和20%的甲醇汽油混合燃料)的微粒排放测量试验.结果表明:微粒数量浓度粒径谱密度呈双峰分布,核态微粒峰值粒径主要集中在23.71~27.38 nm,积聚态微粒峰值粒径主要集中在64.94~86.6 nm,各模态微粒峰值变化与数量浓度变化相同,随喷油时刻的推迟先下降后上升,在80°CA ATDC(进气上止点后)喷油时最少,随甲醇比例的增大先升高后降低,燃用M15时最多;燃用纯汽油M0时,发动机在100°CA ATDC喷油时排放微粒最多,燃用甲醇汽油混合燃料时,发动机在40°CA ATDC喷油时排放微粒最多;微粒表面积浓度粒径谱密度均呈单峰分布,峰值粒径主要集中在86.6~153.99 nm,总表面积浓度变化与总数量浓度变化相同,但变化幅度更大.
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