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在一台可视化直喷式柴油机上完成了旨在调查燃烧室形状对燃烧过程影响的试验研究。揭示了三种不同形状燃烧室的燃烧过程,用互相关法测量了火焰运动特性,例如火焰速度矢量的分布和燃烧室内、外的火焰平均速度。同时采用内窥镜装置来获取有关燃烧室内、外火焰分布的数据。比较不同燃烧室与喷油嘴突出量之间的火焰运动和分布,结果表明,燃烧室形状对火焰速度有显著影响,在膨胀期间,缩口型燃烧室的火焰速度比盆型燃烧室为大。燃烧室壁面形状对燃烧室内、外的火焰分布影响相当大,缩口型燃烧室使火焰不致覆盖挤流区。本文亦讨论了同一发动机在相同试验条件下测得的火焰特性的这些变化与烟度之间的关系。这种关系显示,为了进一步降低烟度,重要的是在扩散燃烧期间要获得大规模的火焰运动,在燃烧室内、外同时获得理想的燃油/火焰分布。
A pilot study on the effects of combustion chamber shape on the combustion process was completed on a visual direct injection diesel engine. The combustion processes of three different shapes of combustion chambers were revealed. The cross-correlation method was used to measure the flame characteristics, such as the distribution of the flame velocity vector and the average flame velocity inside and outside the combustion chamber. Endoscopic devices were also used to obtain data on the flame distribution inside and outside the combustion chamber. The results show that the shape of the combustion chamber has a significant effect on the flame velocity. During the expansion, the flame velocity of the necked-in combustion chamber is larger than that of the basin-shaped combustion chamber . The combustion chamber wall shape has a great influence on the flame distribution inside and outside the combustion chamber, and the neck-in combustion chamber prevents the flame from covering the extrusion flow area. This paper also discusses the relationship between these changes in flame characteristics and smoke as measured by the same engine under the same test conditions. This relationship shows that in order to further reduce the smoke level, it is important to obtain a large-scale flame movement during the diffusion combustion to achieve the desired fuel / flame distribution both inside and outside the combustion chamber.