基于循环的缸内直喷乙醇HCCI燃烧的瞬态空燃比特性研究

Research on Cycle-by-Cycle Real-Time A/F Ratio Characteristics for Ethanol DI-HCCI Combustion

考虑到HCCI燃烧模式对于循环间变动很敏感,基于瞬态CO_2/CO和HC排放测试仪,利用缸内直喷HCCI发动机台架,对乙醇HCCI燃烧循环间的排放及瞬态空燃比进行检测,并采用数学统计的方法分析连续循环的瞬态空燃比变化特性。研究结果表明:喷油量的变化对瞬态空燃比的波动影响最大,发动机转速和进气温度的影响依次降低;瞬态空燃比与缸内燃烧压力峰值显著相关,当瞬态空燃比上升时,缸压峰值降低,反之亦然。

In consideration of HCCI is very sensitive to cycle-by-cycle variation, fast CO2/CO, HC and NO3 measurement systems were employed to detect transient emissions and real-time air/fuel ratios in the ethanol DI-HCCI combustion engine bench test. Based on the statistical method, cycle-by-cycle air/fuel ratio variation was analyzed. Results show that the influence of injection delivery on real-time air/fuel ratio is larger than those of engine speed and intake temperature. There is a close correlation between cycle-by-cycle air/fuel ratio and in-cylinder peak pressure, as the real-time air/fuel ratio increases the in-cylinder peak pressure decreases and vice verse.