文丘里管废气再循环系统对涡轮增压柴油机性能影响的研究

加装文丘里管的高压废气再循环(Exhaust gas re-circulation,EGR)进气系统,在兼顾柴油机经济性、动力性的前提下,研究该进气系统对NO_x排放的影响。根据一款柴油机的基本结构建立柴油机一维仿真计算模型和燃烧室的三维仿真计算模型。在对模型进行标定和对柴油机原机性能仿真计算的基础上,为进气系统引入文丘里管装置并对其结构参数进行优化设计。应用所建立的一维和三维柴油机模型,对文丘里管EGR系统柴油机的经济性、NO_x和Soot排放特性进行仿真计算研究,并对计算结果进行试验验证。研究结果表明,优化设计的文丘里管EGR系统可使柴油机在欧洲稳态循环(European steady state cycle,ESC)各工况下实现较为理想的EGR率,并在不明显影响柴油机燃油经济性的前提下,使NO_x排放量下降了约28.4%。文丘里管进气系统可以实现较为理想的高压EGR循环,在柴油机ESC工况下(怠速除外)能够达到较为理想的EGR率。

Study on the Effects of Venturi-EGR System on Turbo-charged Diesel Engine Performance

A high pressure circulating exhaust gas re-circulation (EGR) intake system with Venturi tube is installed to study the influence of the intake system on the NOx emission in the condition of the economy and power of the diesel engine. According to a diesel engine’s basic structural parameters and test data, the diesel engine’s GT-Power 1D simulation model and the AVL Fire 3D simulation model of combustion chamber is established. Based on the calibration of models and the calculation of the diesel engine performance, the Venturi tube is introduced into the intake system and its structure parameters are designed. The 1D and 3D models of engine are applied for the calculation of the fuel economy and emission characteristic of the vEGR diesel engine, and the results are verified by experiments. The results show that the Verturi EGR system allows the diesel engine to achieve ideal EGR rates under different European steady state cycle(ESC) operating conditions, and the NOx emission could be reduced by 28.4% with no significant impact on the fuel economy. The calculated results consistent with the experimental results and the conclusions are real and effective. Venturi pipe intake system can achieve a more ideal high pressure EGR cycle, in the diesel engine ESC operating conditions(except idling mode) can achieve a more ideal EGR rate.