CFD simulation of spark ignition engine with natural gas at varying compression ratio.

Natural gas offers several advantages such as clean combustion, high octane number (approximately 120), high availability, and attractive price. Additionally, its relatively high auto-ignition temperature is suitable for higher compression engines.CFD modeling of internal combustion engines is playing an increasingly important role in improving engine design, leading to a reduction in fuel consumption and pollutant emissions, a comprehensive insight into the wide-ranging physics, such as the ignition, combustion chemistry, knock occurrence, power output and efficiency. This paper deals with the simulation of Spark Ignition engine fuelled with methane, a major composition of natural gas by varying the compression ratio. The work involves CFD analysis using trimmed unstructured polyhedral moving grid that would complete four strokes of the engine. The simulation was carried out for compression ratios of 9.5:1, 10.5:1, 11:1, 12:1, 14:1 and 15:1. STAR-CD software package was used for simulation and combustion was carried out using ECFM-3Z model. From the analysis, the knocking of the engine was found at a compression ratio of 15:1. The performance parameters such as Indicated power, Indicated mean effective pressure, Indicated specific fuel consumption are calculated. [ABSTRACT FROM AUTHOR]