油嘴喷射锥角对柴油可控预混压燃燃烧特性的影响

Effects of Nozzle Cone Angle on Diesel Premixed Combustion

进行了在柴油可控预混压燃燃烧模式下,油嘴喷射锥角对燃烧与排放的影响研究.实验结果表明,采用155°和125°喷射锥角的油嘴,改变多脉冲喷射定时可控制预混燃烧放热幅度,影响NOx与HC和CO排放的折衷关系.在3次和6次多脉冲喷射条件下,采用125°油嘴能获得更低的NOx和HC排放.特别是采用6次脉冲喷射模式,即使在较早的喷射定时(130°CA BTDC)下,仍能保证较低的HC和CO排放.研究表明,通过减小油嘴喷射锥角、增加脉冲喷射次数和大幅度提前喷射定时,能够在获得低NOx排放的可控预混燃烧过程的同时,保证HC和CO排放只有小幅增加.

Controlled premixed charge compression ignition of diesel engine based on multi-pulse injection was developed. In diesel premixed combustion mode, the effects of nozzle cone angle on emissions were studied. For each cone angle with advanc：ing of the multi-pulse injection timing, NO, emission is reduced, while HC and CO emissions increase. The cone angle of 125° is better for reducing the tendency of spray impinging on the cylinder wall, and for improving the utilization of air in cylinder axial direction. NOx and HC emissions are decreased with the small cone angle for all of the multi-pulse injection timings, and CO and smoke emissions for cone angle of 125° are less than those of cone angle of 155° at large advanced multi-pulse injection timing. The experimental results indicate that reducing nozzle cone angle, increasing injection pulse number, and advancing the injection timing are the effective ways for achieving low NOx emission and maintaining the level of HC and CO emissions.