万源,刘永峰,毕贵军,等.CO2/O2环境对柴油着火及燃烧特性的影响[J].内燃机工程,2023,44(3):44-54.
CO2/O2环境对柴油着火及燃烧特性的影响
Effects of CO2/O2 Environment on Ignition and Combustion Characteristics of Diesel
DOI：10.13949/j.cnki.nrjgc.2023.03.006
关键词:CO2/O2环境  定容燃烧弹  着火过程  火焰自发光强度  第三体作用
Key Words:CO2/O2 environment  constant volume combustion chamber  ignition process  nature flame luminosity  the third body effect
基金项目:国家自然科学基金项目（51976007）；北京建筑大学研究生创新项目（PG2022128）；内燃机燃烧学国家重点实验室开放研究项目（K2023-04）
作者单位E-mail
万源* 北京建筑大学 机电与车辆工程学院，北京 102627 wanyuan0321@foxmail.com 
刘永峰* 北京建筑大学 机电与车辆工程学院，北京 102627 liuyongfeng@bucea.edu.cn 
毕贵军 新加坡科技研究局 制造技术研究院，新加坡 637662，新加坡  
刘海峰 天津大学 内燃机燃烧学国家重点实验室，天津 300072  
张璐 北京建筑大学 机电与车辆工程学院，北京 102627  
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摘要:为研究CO2/O2环境对柴油着火和燃烧特性的影响，以正庚烷为柴油表征燃料，利用CONVERGE计算了不同CO2/O2环境下正庚烷的着火和燃烧过程，并搭建了可视化定容燃烧弹试验平台进行了验证。使用高速摄影机记录了初始温度850 K，初始压力3 MPa，CO2体积分数分别为35%、40%、50%和60%时正庚烷燃烧的自发光强度，利用CHEMKIN中定容均质反应器分析了CO2物理和化学作用对着火的影响。研究结果表明：在CO2体积分数35%时存在爆燃的现象，随着CO2体积分数增长，着火延迟时间增长，着火位置远离喷嘴，稳态燃烧阶段火焰的长度和宽度也增大，CO2体积分数在50%~60%之间时火焰自发光强度峰值明显下降；CO2的物理作用抑制了着火，第三体作用对着火的促进作用大于直接参与反应对着火的抑制作用，造成CO2的化学作用缩短了着火延迟时间，并且随着CO2体积分数增大，化学作用对着火的促进作用更加明显。
Abstract:In order to investigate the effect of CO2/O2 environment on the ignition and combustion characteristics of diesel fuel， using n-heptane as the diesel surrogate fuel， the ignition and combustion process of n-heptane under different CO2/O2 environments were calculated based on the computational fluid dynamics software CONVERGE. The optical constant volume combustion chamber was established to validate the model， and the nature flame luminosity of n-heptane combustion was recorded by high-speed camera. The initial temperature was 850 K， the initial pressure was 3 MPa， and the CO2 volume fractions were 35%， 40%， 50% and 60%. The reaction path of important radicals was calculated by the closed homogeneous reactor in CHEMKIN to analyze the physical and chemical effect of CO2 on ignition. The results show that， deflagration exists at 35% CO2 volume fraction. As the CO2 volume fraction increases， the ignition delay time increases， the ignition position is further away from the nozzle， and length and width of the steady-state flame also increases. The peak intensity of nature flame luminosity decreases significantly when the CO2 volume fraction is between 50% and 60%. The physical effect of CO2 suppresses the ignition， and the chemical effect of CO2 promotes the ignition due to the promotion of ignition by third body effect than the inhibition of ignition by direct chemical effect， and the chemical effect is strengthened with the increase of CO2 volume fraction.
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