汽油机涡轮增压系统数值模拟与优化匹配特性分析

胡辽平^{1, 2}，龚金科^{1, 2}，贾国海^{1, 2}，王曙辉²，蔡皓²

(1. 湖南大学 汽车车身先进设计制造国家重点实验室，湖南 长沙，410082；2. 湖南大学 机械与运载工程学院，湖南 长沙，410082)

摘 要：通过对汽油机可变截面增压(VGT)系统和废气再循环(EGR)系统进行匹配数值模拟，研究VGT增压系统对汽油机动力性和燃油经济性等性能的影响。为了最大程度地提高汽油机的动力性能并且有效降低污染物排放，研究VGT和EGR匹配对汽油机主要性能的影响。研究结果表明：低速低负荷采用一定量的EGR，可提高燃油经济性，但EGR过高，会破坏燃油经济性，最大EGR率可达51%；当中高速中高负荷采用EGR率为0时，燃油经济性提高；若增加EGR率，则会降低燃油经济性，EGR率过大还会导致动力不足。

关键词：汽油机；涡轮增压系统；可变截面增压；废气再循环；燃油经济性

Numerical simulation and optimum matching characteristic analysis for gasoline engine turbocharging system

       HU Liaoping^{1, 2}, GONG Jinke^{1, 2}, JIA Guohai^{1, 2}, WANG Shuhui², CAI Hao²

(1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University, Changsha 410082, China;2. College of Mechanical and Vehicle Engineering, Hunan University, Changsha 410082, China)

Abstract:Through the matching numerical simulation of the variable geometry turbocharger (VGT) system and the exhaust gas recirculation (EGR) system, the effects of VGT turbocharging system on the power and the fuel economy of gasoline engine were researched. In order to realize the goal for imporoving the maximum power and reducing the maximum emissions of gasoline engine, the effects of matching VGT and EGR to the main performance of gasoline engine were studied. The results show that the fuel economy is improved by using a certain amount of EGR rate in the low speed and load, but it is reduced in high EGR rate, and the largest EGR rate achieves 51%. When EGR rate is 0 in high speed and high load, the fuel economy can be improved and it will sacrifice the fuel economy if EGR rate is too large and the power can not reach the target value.

Key words:gasoline engine; turbocharging system; variable geometry turbocharger; exhaust gas recirculation (EGR); fuel economy