柴油机EGR混合器管路结冰分析与结构优化

Analysis of freezing in EGR pipeline of diesel engine and its structure optimization

为解决某发动机在寒区试验中因废气再循环(exhaust gas re-circulation,EGR)混合器管路结冰导致发动机无法起动、动力性能下降等故障,以该发动机进气系统为研究对象,建立进气系统内部流场三维模型,利用STAR-CCM+流体分析软件进行流体仿真(computational fluid dynamics,CFD)计算,结合理论分析,提出EGR混合器布置位置远离进气节流阀、进气加热格栅调整到EGR混合器前和在结冰风险处增加水套结构的优化方案。仿真及寒区试验验证结果表明,改进结构后的发动机可以显著提升各缸的新鲜进气和EGR废气均匀性,避免EGR混合气体在管路内回流,有效解决发动机EGR混合器管路结冰问题。

In order to solve the engine start failure and power loss caused by freezing of exhaust gas re-circulation(EGR)mixer pipeline of an engine in cold operation test,three-dimensional flow field model of the intake system is established by taking the intake system of the engine as the research object.By using STAR-CCM+simulation software,the computational fluid dynamics(CFD)calculation is carried out.Combined with theoretical analysis,the EGR system is optimized.The EGR mixer is positioned far away from the intake throttle,the intake heating grate is adjusted in front of the EGR mixer,water jacket is added at the risk of icing.The results of simulation and cold operation test show that with the above improvements,the uniformity of fresh intake air and EGR exhaust gas of each cylinder are significantly improved,the EGR mixed gas backflow in the pipeline is avoided,and the problem of icing in the EGR mixer pipeline is effectively solved.