摘要
对大涡模型在预测发动机早喷中燃料和空气混合过程的适用性进行研究。将大涡模拟(LES)湍流模型加入KIVA3V程序中,对定容弹中燃油短喷以及在1台Ford高速直喷柴油发动机中的早喷过程进行数值模拟。研究结果表明:LES模型预测的喷雾浓度分布和贯穿距与实验结果较相符,明显比RANS模型的优;在燃烧室中LES模型得到的湍动能和黏性都要比RANS模型的小,而且随着喷射时间的增加,亚网格湍动能和黏性都增加并集中在喷射区域;同时,喷油时刻提前有利于燃油与空气的均质混合,LES模型得到的混合气分布更加均匀,三维紊乱的结构更加明显;与RANS模型相比,ES模型更能真实反映柴油机早喷过程中的喷雾流场。
The feasibility of large eddy simulation（LES） for predicting fuel injection and mixing of early injection in diesel engine was studied.LES turbulent model was implemented into KIVA3V code to make numerical simulation of the atomization and evaporation processes of early injection timing in a constant volume chamber and a ford high-speed direct-injection diesel engine.The results show that the predictive vapor mass fraction and liquid penetration using LES is obviously better than those using RANS model and good agreement with the experiment results.In combustion chamber,the sub-grid turbulent kinetic energy and viscosity using LES is less than those of the RANS models’,and with the increase of time,the sub-grid turbulent kinetic energy and viscosity also increase and concentrate on the spray area.Meantime,advancing the injection timing can help to achieve more homogenous mixture between the fuel and ambient gas.The distribution of the mixture is more uniform and the tree-dimension and disorder structures are more obvious using LES model.Compared to RANS model,LES model can better reflect the real spray flow field of early injection process in diesel engine.
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2012年第9期3678-3686,共9页
Journal of Central South University:Science and Technology
基金
国家重点基础研究发展计划("973"计划)项目(2007CB210002)
中国博士后基金资助项目(2012M510437)
关键词
大涡模拟
喷射混合
早喷
LES（large eddy simulation） model
spray mixture
early injection
