船用直喷式天然气发动机喷射策略的优化

Effect of injection strategy on the combustion and emission characteristics of direct injection natural gas engine

中文关键词: 天然气发动机  高压直喷  数值模拟  喷射时刻  喷射间隔  

英文关键词: natural gas engine  high pressure direct injection  numerical simulation  injection time  injection interval  

中文摘要:

      为了探讨引燃柴油喷射时刻及其与天然气喷射时刻的间隔对高压直喷式天然气发动机燃烧性能的影响，从而优化喷射策略，本文利用CONVERGE软件，基于L23/30型船用天然气发动机，建立了双天然气喷嘴、双引燃柴油喷嘴的直喷天然气发动机的缸内过程CFD计算模型，计算了不同的柴油和天然喷射时刻下缸内燃烧和排放。结果表明，引燃柴油的喷射时刻及其与天然气喷射定时的间隔，对直喷式天然气发动机燃烧和排放性能有重要影响，当喷射时刻为-25°CA ATDC时，发动机具有较高的缸内爆发压力且排放性能良好。在引燃柴油和天然气喷射间隔为16°CA时，可获得最高的缸内爆发压力，此时soot排放降低了22%。

英文摘要:

      To investigate the influence of diesel injection timing and the injection interval between diesel and natural gas on combustion performance of high pressure direct injection natural gas engine, and to optimize the injection strategy, the CFD calculation model of in-cylinder process of dual natural gas injector and dual diesel injector natural gas engine was established by using CONVERGE software and based on L23/30 marine natural gas engine.These results show that the injection time of ignited diesel and its interval with natural gas injection timing have an important influence on combustion and emission characteristics of direct injection natural gas engine. When the injection time of pilot diesel is - 25°CA ATDC, the combustion condition of natural gas engine is higher than that of other simulated diesel injection time, and the average cylinder pressure and emission are better. At this time, when the injection interval of pilot diesel and natural gas is 16 °CA, the highest average cylinder pressure can be obtained, which is conducive to reducing 22% the emission of soot.