A CFD Analysis of a Multi-Fuel Injection System Rail

Flexibility in running with different fuel is becoming an important issue in the Internal Combustion Engine design due to the increasingly wider use of alternative fuels. The injection systems must deal with fuels having different properties and effects on engine behavior and take proper adjustments in the control strategy. Particularly the transient during which one fuel is being replaced by the second one is a critical point of the injection system operation, and its capability of recognizing the fuel mixture currently available is a fundamental matter in the engine control development.This paper focuses on the multidimensional CFD analysis of a Common-Rail-type, multi-fuel injection system accumulator during the gasoline-ethanol shift. An open source computational fluid dynamics code was used in the modelling. A preliminary analysis of an experimental test case available in literature was carried out; different grid resolutions were employed in the simulations in order to asses their influence on the interface and distribution of the fluids. Finally the multi-fuel rail dynamic behavior was investigated under limiting operating conditions, and its effects on the engine functioning are discussed.