Optical diagnostics of early flame development in a DISI engine fueled with n-butanol and gasoline

The research presented in this work is focused on using butanol as gasoline replacement in a Direct Injection Spark Ignition engine. The impact of this fuel on the combustion processes was investigated using optical diagnostics and conventional methods in an optically accessible single cylinder engine. All the measurements were performed at 2000 rpm engine speed. Two different values of intake air pressure were set. Lean burn and stoichiometric mixture in homogenous conditions were investigated. The engine was fuelled with commercial gasoline and pure n-butanol. High spatial and temporal resolution visualization was applied in the first phase of the combustion process in order to follow the early flame development for the two fuels. The optical data were completed with conventional measurements of thermodynamic data and pollutants emission at the exhaust.