均质充量压缩着火燃烧碳氢生成和边界层贡献的试验研究

摘要

试验研究了均质充量压缩着火（HCCI）燃烧过程中边界层区域HC生成、分布与消耗历程,考察了边界层各个区域对整体HC排放的贡献比例。为此,在快速压缩机上利用瞬态HC排放仪测量了均质混合气在当量比0.4、不同压缩比下靠近气缸盖底面和气缸体侧面不同距离的各测点在全反应历程内的HC浓度。研究发现：压缩比降低使得边界层效应更加明显;同一工况下,气缸盖底面和气缸体侧面的边界层厚度因受到压缩挤流和壁面传热的影响而不同,气缸体侧面的边界层效应比气缸盖底面的更加显著;靠近气缸盖底面和气缸体侧面2mm以内的区域对整体HC排放的贡献较高,气缸中心燃烧核心区域贡献较小。%Experimental study was carried out on HC sources, distribution and consumption of HCCI combustion, and also on HC contributions of different regions of boundary layer. These experiments were conducted on an RCM using a fast response HC detector to measure the HC concentrations of different re gions near the cylinder head and the cylinder liner during the combustion process with the equivalent ratio of 0.4 and different compression ratios. Experimental results show that： decrease of compression ratio makes the boundary layer contributions bigger; under the same compression ratio, the thickness of the boundary layer near the cylinder head and the cylinder liner is different because of the influences of the swirl flow and the wall heat transfer, the boundary layer effects of the region near the cylinder liner are more obvious than those of the region near the cylinder head ; the HC contribution of the regions near both the cylinder head and the cylinder liner with thickness under 2mm is bigger, while the HC contribution of the core combustion region around the cylinder centerline is smaller.