一种基于稀扩散燃烧的BUMP燃烧室及其对柴油机碳烟和NOx排放影响的实验研究

在壁面布置限流沿 (BUMP)后 ,撞壁射流从壁面被剥离 ,形成二次空间射流 ,可大大加快空气与流体的混合速率。基于此 ,设计了带有 BUMP的燃烧室 ,采用了可灵活控制喷油规律的 FIRCRI电控共轨式喷油系统进行了发动机实验。实验结果表明 :BU MP燃烧系统能显著降低 NOx 和碳烟排放 ,在平均有效压力为 0 .6 6 MPa(原机 5 0 %负荷 )时 ,烟度只有 0 .1BSU,NOx 为 42 0× 10 - 6;由于在缸内能够形成较均匀的混合气 ,缸内平均过量空气系数在 1.3～ 2 .0的范围内时 ,烟度一直保持在 0 .3BSU以下。实验还发现 BUMP的位置以及喷油定时对排放有重要影响。BUMP燃烧系统在降低 NOx 和碳烟排放方面显示了极大的潜力。

The BUMP Combustion Chamber Presented Based on the Concept of Lean Diffusion Combustion in a D. I. Diesel Engine with Common Rail Fuel Injector

Diesel fuel spray always impinges with the wall of combustion chamber of a D.I. diesel engine with a small or middle bore.It was found from author's fundamental research that a thin and rich wall jet of fuel/air mixture forms on the wall with a very low mixing rate with air in the combustion chamber.However,a bump on the wall of the combustion chamber can strip the wall jet off and forms a secondary space jet with much higher mixing rate.This finding has been applied to a supercharged D.I.diesel engine which is equipped with a common rail fuel injector system named FIRCRI.By means of the BUMP combustion chamber,a so-called "Lean Diffusion Combustion Concept" is realized.The results of engine test show that the bump combustion system can reach very clean combustion at conditions lower than BMEP of 0.66 MPa.However,either soot or NO x emissions gets worse when BMEP is higher than 0.9 MPa.Further improvement of both design of BUMP combustion chamber and injection parameters is needed.