甲醇缸内直喷发动机的燃烧特性

Combustion Characteristics of a Direct-Injection Spark-Ignition Methanol Engine

在一台四缸柴油机改造的复合导流分层燃烧缸内直喷火花点火甲醇发动机上，开展了燃烧特性的试验研究．研究表明：该甲醇发动机的最大压力位于上止点后14°～17°的位置，离上止点较近，燃烧定容性好，热效率高；最大压力升高率低，发动机工作柔和，燃烧噪声低；燃烧放热率曲线的形状与传统汽油机预混燃烧单峰形状相似，没有出现扩散燃烧导致的双峰放热现象；在宽广的转速和负荷范围下，平均指示压力的循环变动不超过10％，燃烧稳定性好．

A complex-guided stratified charge combustion system for a direct-injection spark-ignition （DISI） methanol engine was developed. The test engine was retrofitted from a 4-cylinder diesel engine. The experiment of the engine combustion characteristics was conducted and analyzed, The results show that the maximum cylinder pressure occurred from 14° CA ATDC to 17° CA ATDC, yielding a good constant volume and a higher thermal efficiency. The maximum rate of pressure rise was lower and then the combustion noise decreased. The curves of the heat release rate of the developed DISI methanol engine had single peaks without diffusion burning, similar to those of the PFI engine. The cyclic variations of imep were lower than 10% in a wide range of operating conditions, which shows a stable stratification combustion.