发动机早喷过程中燃油喷射混合的大涡模拟
来源期刊：中南大学学报(自然科学版)2012年第9期
论文作者：周磊 解茂昭 贾明 史俊瑞
文章页码：3678 - 3686
关键词：大涡模拟；喷射混合；早喷
Key words：LES (large eddy simulation) model; spray mixture; early injection
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。
Abstract: 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.
周磊1, 2，解茂昭1，贾明1，史俊瑞3
(1. 大连理工大学 能源与动力学院，辽宁 大连，116024；
2. 清华大学 燃烧能源中心，北京，100084；
3. 沈阳工程学院 动力系，辽宁 沈阳，110136)
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。
关键词：大涡模拟；喷射混合；早喷
ZHOU Lei1, 2, XIE Mao-zhao1, JIA Ming1, SHI Jun-rui3
(1. School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, China;
2. Center for Combustion Energy, Tsinghua University, Beijing 100084, China;
3. Department of Power Engineering, Shenyang Institute of Engineering, Shenyang 110136, China)
Abstract: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.
Key words:LES (large eddy simulation) model; spray mixture; early injection
