复合供气压燃式天然气发动机的燃烧特性  

Combustion Characteristics of a Compression Ignition Natural Gas Engine with Multiple Fuel Supply Systems

作　　者：郑清平[1] 张惠明[2] 李方成[2] 焦运景[2] 张德福[2] 

机构地区：[1]天津工业大学机电学院,天津300160 [2]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《燃烧科学与技术》2008年第2期101-106,共6页Journal of Combustion Science and Technology

基　　金：国家自然科学基金(50276041);天津市高等学校科技发展基金(20030802)

摘　　要：根据分层燃烧理论,设计了分隔室复合供气压燃式天然气发动机燃烧系统.采用化学动力学简化机理模型与CFD耦合对发动机的着火和燃烧过程进行了模拟计算,并验证了模拟计算结果的有效性.结果表明,进气温度、电热塞温度、喷气时刻、供气量对发动机的燃烧特性有较大影响.进气温度过高时,燃烧趋向单级燃烧,将导致爆燃,而且产生较高的NO排放.电热塞温度过高同样导致高的燃烧速率,增大爆燃趋势;高压供气时刻提前使燃烧压力、温度和压力升高率上升,NO排放随之增加;在现有的较低喷气速率下,当缸内喷气持续期控制在40～50°CA时,燃烧时刻最佳;当进气道供气量比例较高时,会发生敲缸现象.A combustion system, with a separated combustion chamber and multiple fuel supply systems in a natural gas engine, is designed based on the stratification combustion theory. Simulation of ignition and combustion processes of the engine is carried out by coupling the multidimensional computational fluid dynamic （CFD） code with the simplified chemical kinetic mechanism. The results show that inlet air temperature, glow plug teoaperature, injection timing and quantity of natural gas supply have much influence on ignition and combustion characteristics of the natural gas engine. If inlet air temperature is too high, the combustion process tends to have only one stage, resulting in cylinder knocking, and NO emission is higher as well. Too high tempemture on glow plug will also lead to high combustion speed and increase engine knocking tendency. Advance of gas supply timing will increase combustion pressure, temperature and pressure rising rate, and NO emission will increase accordingly. At the current lower gas injection rate, optimized combustion timing is realized when in-cylinder gas injection duration is from 40° CA to 50° CA. Too high gas supply propertion through the inlet manifold will also cause cylinder knocking.

关 键 词：天然气发动机 压缩燃烧 复合供气 模拟 燃烧特性 

分 类 号：TK432[动力工程及工程热物理—动力机械及工程]