Analysis On The Air/Fuel Mixing For Turbocharged Gasoline Direct Injection Engine And Optimization Of Performance Parameters

Turbocharged direct injection engine is the development trend of future gasolineengines, but the quality of the air/fuel mixture determines the engine’s combustionefficiency and emission level. The organization and control of the air/fuel mixingprocess are the key technologies.This thesis studies on turbocharged gasoline direct injection engine， analyzedthe airflow in cylinder and fuel spray characteristics by test, and validated itsnumerical model on the basis of experimental results. To prevent fuel droplets kittingthe cylinder walls, get uniform mixture concentration in the combustion chamberspace and obtain stable and reliable mixture quality near the ignition timing sparkplug as the goals, the performance parameters have been optimized. The mainresearch work and innovation are as follows：(1) Through the reverse engineering and parametric design methods, thecombustion chamber and the intake port geometrical model was obtained. Thenanalyzed the intake port performance by air flow rig test and calibrated the intakeport CFD model against air flow rig test data.(2) Analyzed the fuel spray characteristics by a spray experiment which takes ina constant volume combustion bomb. The fuel spray model was then verified to thelaser photographing pictures and data.(3) Constructed the air/fuel mixture simulation model. The air/fuel mixingprocess at2000rpm full load conditions was simulated by AVL-FIRE CFD software.The influence on the air/fuel mixing process ware analyzed from different injectionangles, injection timings and injection durations. Optimized the performanceparameters and improved the quality of the air/fuel mixture. This method can beextended to all the conditions of the engine and improve the quality of the air/fuelmixture in the full range.