GDI发动机与涡轮增压器匹配性能

涡轮增压系统决定了发动机的进气能力，严重影响整机燃烧性能。为优化汽油缸内直喷(gasoline directinjection, GDI)发动机的热效率，利用GT-Power软件搭建了一维仿真计算模型，并基于试验数据完成模型标定。通过热力学仿真计算，分析了不同增压系统对发动机动力性、经济性的影响。研究结果表明：采用定压增压结构，能减少泵气损失，提高发动机在高速工况时的热效率。但其低速性能较差，不满足车用发动机对低速转矩特性的要求。采用脉冲增压结构能有效改善发动机扫气，低速时压气机喘振裕度大。为解决脉冲增压结构高速工况涡端效率较低的问题，扩宽了涡前流道并使用大流量涡轮机方案，使泵气损失明显减少，最大功率点比油耗降低了11.7 g/(kW·h)。证明该措施有效提高了汽油机性能，满足开发需求。

Research on Matching Performance of GDI Engine and Turbocharger

The turbocharging system determines the intake capacity of the engine and seriously affects the combustion performance of the whole engine. In order to optimize the thermal efficiency of gasoline direct injection (GDI) engine, a one-dimensional simulation model was built by using GT power software, and the model calibration was completed based on the test data. Through thermodynamic simulation, the influence of different supercharging systems on engine power and economy is analyzed. The research results show that the use of a constant pressure turbocharging structure can reduce pumping losses and improve the thermal efficiency of the engine under high-speed operating conditions. However, its low-speed torque characteristics are poor, which does not meet the requirements of vehicle engines for low-speed performance. The impulse supercharging structure can effectively improve engine scavenging, and the compressor surge margin is large at low speed. For solve the problem of low efficiency of the vortex end in high-speed working conditions of the pulse turbocharging structure, the flow path before the vortex is widened and the large-flow turbine solution is used. The pumping loss is significantly reduced, and the specific fuel consumption at the maximum power point is reduced by 11.7 g/kWh. This measure effectively improves the performance of gasoline engine and meets the development needs.