进气组分耦合喷油定时对柴油机工作过程的影响机理

发布时间：2018-07-04 18:43

本文选题：柴油机 + 喷油定时　；参考：《内燃机学报》2016年03期

【摘要】：通过一台共轨柴油机,基于正庚烷/甲苯/正己烯混合物简化动力学机理耦合三维CFD数值模型,模拟不同进气组分(O_2、H_2和CO_2)耦合喷油时刻对发动机工作过程的影响机理.研究表明:不同进气组分下,随喷油时刻提前,缸内活性自由基(OH、O)质量分数及其分布区域增大,NO生成量增多.但随喷油时刻过度提前,燃烧始点反而推迟,燃烧放热速率、缸内燃烧压力与温度峰值降低,NO也相应减少;相比其他进气组分,进气掺O_2时缸内O自由基质量分数增大,碳烟(Soot)降低且喷油时刻对其影响较小;进气掺H_2时,缸内燃烧压力和温度峰值最高,OH自由基质量分数及分布区域最大,Soot随喷油定时提前大幅降低;进气掺CO_2时,缸内燃烧压力与温度峰值最低,OH和O活性自由基最少,当喷油时刻提前超过24°CA BTDC时,燃油逐渐喷射到压缩余隙容积形成局部过浓区,C_2H_2和多环芳香烃芘(A_4)生成量增多,Soot排放随喷油定时进一步提前明显升高.
[Abstract]:Based on the simplified dynamic mechanism of n-heptane / toluene / n-hexene mixture in a common-rail diesel engine, a three-dimensional CFD numerical model was developed to simulate the effect of different intake components (O _ 2H _ 2 and CO _ 2) on the engine working process. The results show that with the advance of injection time, the mass fraction of OHO and its distribution area increase with the advance of injection time. However, with the excessive advance of fuel injection time, the starting point of combustion is delayed, the combustion heat release rate, the peak value of combustion pressure and temperature in cylinder decrease, and the mass fraction of O free radical increases when O _ 2 is added into the cylinder compared with other intake components. Soot (soot) is reduced and the time of injection has little effect on it. When H _ 2 is added into the cylinder, the maximum combustion pressure and temperature peak value of OH radical mass fraction and its distribution region decrease significantly with the injection timing, and when CO _ 2 is added into the cylinder, the combustion pressure and temperature are the highest. The combustion pressure and temperature in cylinder are the lowest, the free radicals of OH and O are the least, when the injection time is higher than 24 掳CA BTDC, The fuel was injected into the compressing clearance volume forming local overconcentration region C2Hs _ 2 and polycyclic aromatic hydrocarbon pyrene (A4). The Soot emission increased significantly with the injection timing.
【作者单位】：昆明理工大学云南省内燃机重点实验室;
【基金】：国家自然科学基金资助项目(51366007) 云南省应用基础研究面上资助项目(2013FB019) 云南省院省校科技合作资助项目(2013ID001)
【分类号】：TK421

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