进气运动对汽油机瞬态冷起动混合气形成影响的研究  

Numerical Study on Effect of Air Flow on Combustible Mixture Formation in Gasoline Engine During Transient Cold Start

作　　者：孔彤[1,2] 韩志玉[1,2] 刘云[1,2] 

机构地区：[1]湖南大学汽车车身先进设计制造国家重点实验室,长沙410082 [2]湖南大学先进动力总成技术研究中心,长沙410082

出　　处：《西安交通大学学报》2013年第11期35-42,共8页Journal of Xi'an Jiaotong University

基　　金：国家高技术研究发展计划资助项目(2008AA11A116);国家科技支撑计划资助项目(2009BAG13B00)

摘　　要：采用计算流体力学软件CONVERGE对进气道喷射汽油机冷起动阶段可燃混合气的形成进行了三维数值计算,计算中采用多组分燃油模型研究了转速、气门升程、非对称气门升程、进气道导流板及进气正时对混合气形成的影响规律。结果表明:冷起动阶段,随着起动转速的提高,缸内当量比有所下降,缸内湍动能大幅度提高;低气门升程时缸内会出现逆时针滚流,滚流比降低;非对称气门升程时缸内切向滚流比和涡流比大幅度提高;进气道中加入导流板时缸内滚流比和湍动能提高,闭阀喷射时缸内混合气更浓、混合更充分,开阀喷射时缸内混合气更均匀,由此避免了局部浓区出现;推迟进气门的开启能明显增加混合气充量,提高缸内当量比。The three-dimensional numerical simulation on the air-fuel mixing process under the cold start condition for a port fuel injection engine was performed by using the CONVERGE CFD software.A multi-component fuel model was adopted to study the effects of different design parameters on the air-fuel mixing process,including the engine speed,variable valve lift,asymmetric valve lift,inlet deflector,and intake valve timing.The results show that the air-fuel equivalence ratio decreases slightly and the turbulent kinetic energy （TKE） in the cylinder increases significantly with an increase in the engine speed in the cold start stage.A counterclockwise tumble appears in the cylinder and the tumble ratio decreases at low valve lift.Using asymmetric valve lift can increase the cross tumble ratio and swirl ratio greatly,and the inlet deflector will raise the tumble ratio and TKE.Slightly rich mixture can be formed by using closed-valve-injection,and the uniformity of the mixture is better by using open-valve-injection.The equivalence ratio can be increased by retarding the intake valve timing.

关 键 词：汽油机 冷起动 混合气 数值模拟 

分 类 号：TK422[动力工程及工程热物理—动力机械及工程]