为评估当量比燃烧工况下掺烧甲醇裂解气对甲醇发动机性能的影响，以一台点燃式甲醇发动机为原型，建立三维仿真模型，并通过不同工况下的缸内压力试验数据进行模型标定。基于标定模型研究了当量比燃烧情况下不同裂解气替代比对发动机性能的影响。结果表明：增大甲醇裂解气替代比会导致缸压峰值、放热率峰值上升，且相应的曲轴转角提前，燃烧重心前移，燃烧持续期缩短。甲醇裂解气替代比增大，相应的发动机循环指示功逐渐减小，主要原因在于当量比燃烧情况下进入缸内的燃料质量及其总热值降低。在考虑尾气余热回收后，增大裂解气的替代比，指示热效率会有所上升，呈现先增大后减小的趋势，在替代比为50%时达到最大值41.26%。

In order to evaluate the effect of dissociated methanol gas on the performance of methanol engine under the equivalent ratio combustion condition, a 3D simulation model was established based on a methanol ignition engine and calibrated by the experimental data of cylinder pressure. The influences of different substitution proportions of dissociated methanol gas on the engine performance were then studied based on the calibrated model. The results show that increase of substitution ratio will increase the maximum cylinder pressure and heat release rate, advance the corresponding crank angle and combustion center, and shorten the combustion duration. The indicated power of engine decreases gradually with the increase of substitution ratio mainly due to the decline of injection fuel mass and total heat value under the condition of equivalent ratio combustion. After considering the exhaust heat recycle, increasing substitution ratio will lead to the increase of indicated thermal efficiency, which shows a trend of increase first and then decrease and reaches the peak of 41.26% when the substitution ratio is 50%.