提出了一个火花点火发动机准维燃烧模型。该模型是在双区热力学过程的基础上 ,采用基于皱折火焰面分形理论来描述火花点火发动机气缸内的湍流燃烧及火焰传播速度 ,并确定了其他子现象的计算方法。利用该模型 ,对在快速压缩膨胀机中模拟的沼气发动机燃烧过程进行了模拟计算。计算结果与实测值吻合较好 ,证实了该模型的合理性 A quasi-dimensional combustion model of spark ignition engine is proposed. Based on the double-zone thermodynamic process, this model describes the turbulent combustion and flame propagation velocity in the cylinder of a spark-ignition engine based on fractal flame surface fractal theory, and determines the calculation method of other sub-phenomena. The model was used to simulate the combustion process of biogas engine simulated in a rapid compression expander. The calculated results are in good agreement with the measured values, which proves the rationality of the model