电增压及EGR共同作用下对降低汽油机燃油消耗率的试验研究

基于光学定容燃烧弹试验平台，通过高速纹影摄像系统在相同甲烷燃料初始温度、压力及混合气浓度下，定量分析了不同结构预燃室湍流射流点火（turbulent jet ignition， TJI）的燃烧特性，包括火焰传播速度、火焰面积、火焰形态及燃烧压力等参数。研究结果表明，预燃室孔径越小，相同时间内火焰传播得越远，火焰传播速度和火焰面积增长速度越快，燃烧压力峰值越高。随着预燃室孔径减小，着火机理会由射流中带有火焰的火焰点火转变为火焰过孔时熄灭的喷射点火。喷射点火着火时刻延迟，初始火焰速度减慢，但燃烧压力峰值受影响不大。多级加速预燃室压力升高率与压力峰值与单孔预燃室相比变化不大。虽然火焰出口时速度较慢，但是火焰出口时刻提前且速度衰减较弱，因此多级加速预燃室火焰速度在短时间内超过单孔预燃室，并且压力和火焰面积也更早达到最大值。

Experimental study on reducing fuel consumption rate of gasoline engine under the combined action of electric supercharging and EGR

In order to reduce the BSFC of supercharged Miller cycle engine, a 1.5L turbocharged direct injection gasoline engine was modified to improve its compression ratio and intake tumble. A comparative experimental study on reducing BSFC by electric supercharging and exhaust gas recirculation (EGR) was carried out. The experimental results show that the high compression ratio EGR scheme can significantly reduce the BSFC of the engine, the BSFC decreases by 5% to 13.6%, and the maximum effective thermal efficiency reaches 41.2%, which is mainly due to the reduction of heat transfer loss, air exchange loss and the increase of expansion work. Increasing EGR rate can reduce the heat transfer loss and advance the combustion center, which is the main reason for the decrease of BSFC, and the key to improve EGR tolerance is to optimize combustion structure to reduce ignition delay and combustion duration.