Preparation of air-fuel mixture is considerably dependent on the fluid flow dynamics in order to achieve improved performance, efficiency, and engine combustion in the appearance of flow. In this study, effects on a spark ignition engine of mixtures of hydrogen and compressed natural gas have been numerically considered. This article presents the results of a direct injection engine with mixtures of hydrogen in methane of 0, 7, and 15% by volume. The result shows that the percentage of hydrogen in the CNG increases the burning velocity of CNG and come down the optimal ignition timing to obtain the maximum peak pressure of the engine running with blending of hydrogen to CNG. With adding hydrogen to natural gas, the peak heat release rates increase. For 15% hydrogen, the maximum values at crank angles for in cylinder temperature and heat release rate achieved at 8 degree of CA and the maximum temperature is about 150 K. Port injection gasoline was converted into direct injection by compressed natural gas fuel in this engine.

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