Influence of combustion efficiency on the operation of spark ignition engines fueled with methane and hydrogen investigated in a quasi-dimensional simulation framework
Within the context of widening application of numerical simulations for shortening engine development times, the present work covers the issue of quasi-dimensional simulation of spark ignition engines. Multi-fuel operation was the main goal of the study, with the analysis of methane and its blends with hydrogen; gasoline was also considered as a reference case. Data recorded on two engines with practically the same geometry, was used for calibrating the model. The first power unit was of commercial derivation for small applications, while the second one featured optical accessibility through the piston crown. The relative difference between the two engines allowed the top-land region crevice to be identified as the major contributor to overall combustion efficiency. Using an in-cylinder pressure based method, compression ratio and blow-by losses were determined, and differences between fuel types were recognized in the sense of combustion efficiency.