摘要
低速大负荷工况下,高功率密度增压汽油机会产生一种由早燃引起的,破坏性极大的非正常燃烧现象——"超级爆震"。本文中采用CFD耦合化学反应动力学对一台增压热力学单缸汽油机中由机油液滴诱发的早燃进行了多维数值模拟。研究中采用离散液滴模型模拟了机油喷入燃烧室内与燃油空气混合气发生混合的物理过程,采用一种简化的化学反应机理(包含十六烷、异辛烷)模拟了机油/燃油/空气混合气在燃烧室内的化学反应过程。模拟结果与台架试验结果一致,说明模拟可以预测发动机中的早燃现象。结果表明,机油液滴的引入会促使增压汽油机发生早燃现象。随着机油喷射时刻的推迟,机油的蒸发量增加,可燃混合气发生早燃的时刻提前。
A kind of abnormal combustion phenomenon called‘super knock',caused by pre-ignition,may occur in high power density supercharged gasoline engine under low speed and high load operation conditions. In this paper,a multi-dimensional numerical simulation on the pre-ignition in a thermodynamics single cylinder supercharged gasoline engine is conducted by applying CFD-coupled chemical reaction kinetics. In the study,discrete droplet model is adopted to simulate the physical process of oil injection into cylinder and its mixing with fuel-air mixture,while a simplified chemical reaction mechanism( including cetane and isooctane) is used to simulate the chemical reaction process of oil/fuel/air mixture in combustion chamber. Simulation results are consistent with test ones,demonstrating simulation can well predict pre-ignition phenomenon in engine. The results show that the bringing-in of oil droplets can induce pre-ignition. With the retarding of oil injection timing,the evaporated mass of oil increases,leading to the advance of pre-ignition timing of combustible mixture.
出处
《汽车工程》
EI
CSCD
北大核心
2018年第1期1-6,共6页
Automotive Engineering
基金
北京建筑大学科研基金资助项目(00331616017)、北京市自然科学基金重点项目(KZ201510016019)和天津大学内燃机燃烧学国家重点实验室开放基金(K2017-07)资助.
关键词
增压汽油机
早燃
机油液滴
supercharged gasoline engine
pre-ignition
oil droplet
