摘要
针对不同海拔下压燃式航空活塞发动机预喷的影响作用,在发动机台架试验验证的基础上进行了海拔2~4 km,不同预喷策略下的燃烧与排放仿真分析。结果表明:在中转速巡航工况下,随着预喷油量占比增加,放热率峰值降低,缸内压力峰值升高,燃烧始点与燃烧重心提前,燃烧持续期延长,CO,HC与NO_(x)排放均呈升高的趋势;当预喷间隔角增加时,放热率峰值略有升高,缸内压力峰值降低,尽管CO,NO_(x)排放降低,HC排放却是升高的。巡航高度为2 km,3 km,4 km时,采用预喷油量占比4%,预喷间隔角14°CA的方案,相比于单次喷射CO,HC与NO_(x)排放值分别平均降低约7.83%,25.63%与17.04%。在高转速爬升工况下,采用较小的预喷油量占比可以提升发动机输出功率并改善排放,但当预喷油量占比和间隔角增加时,最大燃烧温度、缸内压力与压力升高率均逐渐升高。总之,4%预喷油量占比和14°CA预喷间隔角的方案在不同海拔下均能保持较好的发动机功率输出,还能有效降低CO,HC与NO_(x)的排放。
Based on the verification of engine bench tests,simulation analysis of combustion and emission is conducted for different pilot injection strategies on compression-ignition aero piston engine between the alti⁃tudes of 2~4 km.The results show that under the cruising condition of medium speed,with the fuel quantity pro⁃portion of pilot injection increases,the peak heat release rate decreases,the maximum cylinder pressure rises,the starting point and core point of combustion advance,the combustion duration prolongs,the CO,HC,and NO_(x)emissions all show an increasing trend.When the interval angle of pilot injection increases,the peak heat re⁃lease rate slightly rises and the maximum cylinder pressure decreases.Although CO and NO_(x)emissions decrease,HC emissions increase.At cruising altitudes of 2 km,3 km and 4 km,CO,HC and NO_(x)emissions are reduced by an average of about 7.83%,25.63%and 17.04%respectively with pilot injection fuel quantity proportion of 4%and pilot injection interval angle of 14°CA compared to single injection.Under the climbing condition of high speed,a smaller proportion of pilot injection can increase the engine output power and improve emissions,but when fuel quantity proportion and interval angle of pilot injection increase,the maximum combustion tempera⁃ture,cylinder pressure and pressure rising rate will gradually ascend.In summary,the scheme of 4%pilot injec⁃tion fuel quantity proportion and 14°CA pilot injection interval angle can not only maintain a better engine output power under different altitudes,but also effectively reduce CO,HC,and NO_(x)emissions.
作者
徐劲松
刘保含
陈科中
XU Jinsong;LIU Baohan;CHEN Kezhong(Faculty of Civil Aviation and Aeronautics,Kunming University of Science and Technology,Kunming 650500,China)
出处
《推进技术》
EI
CAS
CSCD
北大核心
2024年第12期227-236,共10页
Journal of Propulsion Technology
基金
国家自然科学基金(61863017)。
关键词
压燃式航空活塞发动机
预喷
燃烧与排放
巡航
爬升
Compression-ignition aero piston engine
Pilot injection
Combustion and emission
Cruis⁃ing
Climbing
