通道尺寸对热面点火天然气发动机工作过程的影响

针对缸内直喷压燃式天然气（CNG）发动机低负荷循环波动大及高负荷NOx排放偏高的问题，设计开发了涡流室式热面点火燃烧系统，研究了涡流室通道尺寸对缸内天然气空气混合气形成、着火燃烧及发动机运转特性的影响．结果表明：选择直径较大的涡流室通道，发动机起动性能较好且缸内混合气燃烧持续期短，对改善发动机的有效热效率有利；选择直径较小的涡流室通道，主副燃烧室内混合气的浓度分层效果明显，能够实现两级燃烧过程，有利于降低发动机循环波动，扩展功率范围及改善NOx排放。

Effects of Passage Size on Operating Properties of Divided Chamber Compressed Natural Gas Engine Ignited by Glow Plug

To solve the problems that cyclic variation is high in low power output and NOx emission is high in high power output in compression ignition engine with compressed natural gas（CNG） direct injection, a swirl chamber combustion system with glow plug ignition was developed. The effects of the passage size between main swirl com- bustion chamber on the CNG/air mixture formation, ignition and combustion were investigated. Results show that with passage diameter increased properly, engine＇s starting ability could be improved and its effective thermal efficiency could be increased, while with passage diameter decreased, CNG concentration between main swirl chamber is much stratified, which is helpful for achieving stable combustion, extending load range and reducing NOx emission.