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Butanol is deemed as the potential alternative fuel for future development, and the previous researches show poor injection spray atomization when high butanol concentration blended fuel applying on stock small scooter engines. In this research, a platform is built to observe the spray atomization phenomena with 2.5kg/cm2 (2.452bar) 、 3.5kg/cm2(3.433bar) injection pressures and various n-butanol volume percent concentration blended fuels, B60, B80 and B100. After that, engine experiments are undergone with above conditions under wide open throttle (WOT) with stoichiometric air fuel ratio (AFR) at 4000rpm. The experiment results are analyzed and discussed from different aspects eventually. Injection spray observation shows that worse spray atomization appears accompanied with higher concentration blended fuel. But when the injection pressure increases, higher shear force acting on the injection spray improves the breakup of fuel and enhances the effect of fuel spray atomization.

Fuel film dynamics in the intake manifold are considered to develop air fuel ratio (AFR) control strategy with on-line system identification for a V2 engine in this paper. A1000 cc four-stroke two-cylinder, water-cooled port injection SI engine is used as the target engine to develop the engine model in Matlab/Simulink. The model which consists of charging, fueling, combustion, friction, and engine rotational dynamics is used to verify the proposed AFR control. Since the fuel film dynamics changes with different engine operating conditions, the fuel film parameters are often listed as look-up tables for fuel film dynamics calculation in the conventional AFR control. However, those parameters might be inaccurate during transient engine operation. Different intake port temperature will affect the accuracy of those fuel film parameters as well. In order to solve this problem, recursive least square (RLS) is used to identify those parameters on-line.