基于氢射流点火的稀薄煤层气发动机燃烧特性研究  

Study on combustion characteristics of lean coalbed methane engines based on hydrogen jet ignition

作　　者：廖宽 何义团[1] 张军[2] 王乾[1] 秦子涵 付艳艳 Liao Kuan;He Yituan;Zhang Jun;Wang Qian;Qin Zihan;Fu Yanyan(College of Traffic&Transportation,Chongqing Jiaotong University,Chongqing 400074,China;School of Mechatronics and Vehicle Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通大学交通运输学院,重庆400074 [2]重庆交通大学机电与车辆工程学院,重庆400074

出　　处：《能源与环保》2024年第11期138-144,共7页CHINA ENERGY AND ENVIRONMENTAL PROTECTION

基　　金：国家自然科学基金(52276100);重庆交通大学研究生科研创新项目(CYS23500)。

摘　　要：氢气是高活性气体,将氢射流火焰用为种子火焰已经成为低品位燃气,如低浓度煤层气的燃烧应用研究的热点方向之一。面向发动机的氢射流点火由于直喷与点火间的相位差异会诱导不同引燃模式,进而影响发动机的性能。采用数值仿真方法,建立了预混稀薄煤层气+氢气直喷点火的大缸径发动机三维模型,通过对比喷氢—点火相位差(Φ)对发动机缸内火焰传播、火焰结构以及发动机指示热效率的影响,研究了基于氢气射流的点火模式对发动机燃烧特性的影响。结果表明,当Φ>70°CA,缸内点火后表征为均质燃烧;当20°CA≤Φ≤70°CA,缸内点火后表征为逆向浓度分层燃烧;而当Φ<20°CA,则形成烟羽点火燃烧。当喷氢时刻为30°CA BTDC,点火角为25°CA BTDC时,烟羽点火燃烧取得最高指示热效率,达到39.3%,同时对比均质燃烧与逆向浓度分层,烟羽点火的火焰发展期缩短11.9%与22.1%,燃烧持续期缩短1.1%与1.6%。Hydrogen is a highly reactive gas,and using hydrogen jet flames as seed flames has become one of the hot research directions for the combustion application of low-grade gases,such as low concentration coalbed methane.Hydrogen jet ignition for engine applications induces different ignition modes due to the phase difference between direct injection and ignition,thereby influencing engine performance.This study employed numerical simulation methods to establish a three-dimensional model of a large-bore engine with direct injection ignition of premixed lean coalbed methane+hydrogen.By comparing the effects of hydrogen injection ignition phase difference(∅)on engine cylinder flame propagation,flame structure,and engine indicated thermal efficiency,the impact of hydrogen jet ignition mode on engine combustion characteristics was investigated.Results reveal that when∅>70°CA,post-ignition in-cylinder conditions are characterized by homogeneous combustion;wheN_(2)0°CA≤∅≤70°CA,post-ignition conditions exhibit inverse concentration stratification combustion;while when∅<20°CA,flame feathering ignition combustion occurs.At a hydrogen injection timing of 30°CA BTDC and ignition angel of 25°CA BTDC,flame feathering ignition combustion achieves the highest indicated thermal efficiency of 39.3%.Comparatively,in contrast to homogeneous combustion and inverse concentration stratification,flame feathering ignition reduces flame development period by 11.9%and 22.1%,and combustion duration by 1.1%and 1.6%,respectively.

关 键 词：喷氢射流 火焰结构 烟羽点火 燃烧特性 

分 类 号：U464[机械工程—车辆工程]