非道路国Ⅳ柴油机燃烧室出口特征形状影响研究

Optimizing Convex Platform Combustion Chamber Design for Non-road Ⅳ Stage Diesel Engine

以某非道路国四高压共轨柴油机为研究对象,通过数值模拟研究了预混合低温燃烧模式下的非道路柴油机高凸台型燃烧室几何参数对缸内气流运动特性、油气混合过程以及污染物排放影响。结果表明:缩口型式可以提高高凸台燃烧室缸内湍流动能,且上止点前会在喉口处形成剧烈涡旋运动,有利于燃油的扩散;缩口燃烧室中的高湍流动能与合理的气流运动可加速燃油的蒸发雾化,气流运动速度与方向较为合理,可以加快油气混合速度,从而可提高油气混合质量;缩口燃烧室在碳烟排放方面具有较大优势,但由于其预混合燃烧比例大,NOx排放相对其他2种燃烧室高。

Taking a non-road diesel engine as the study object,the influence of characteristic shape of outlet of the convex platform combustion chamber on the air flow movement in cylinder and the air-fuel mixture process and emission under the premixed low temperature combustion model.The results show that the re-entrant combustion chamber has a bigger superiority in the air flow movement characteristics,air-fuel mixture and the emission performance.It can strengthen the mixture of air and fuel under the condition of early injection timing.