Numerical Study of Transient Multi Component Fuel Injection 2013-01-2550
Direct injection of gasoline fuel has been gaining on applicability in recent years. Direct injection spark ignited engine has been one of the most investigated designs for achieving lower fuel consumption and for increasing the performance. Maintaining low emissions, decreasing fuel consumption and keeping driving performance are key challenges. Fuel injection quality is one of the most important factors, which directly affect general engine requirements like fuel mass flow, spray penetration and atomization for the combustion process. The multi-hole injector design is a very promising design type for application in direct fuel injection in automotive petrol engines. As a consequence of decreasing supplies of fossil fuels, mixing of different fuel components has become very common in recent years. The type of components which are to be mixed depends on local geographical fuel availability and motorization type. Gasoline fuel can be mixed with ethanol, whereas diesel fuel can be mixed with different bio-diesel fractions. Importantly, fuel injection equipment stays of course unchanged regardless of the ratio of different fuel types. It is crucial to assure consistent mixture formation and finally combustion inside internal combustion engines, regardless of Multi Component Mixture (MCM) nature. The paper focuses on gasoline/ethanol mixture. Based on a numerical experiment it illustrates the capability of the commercial Computational Fluid Dynamics (CFD) code AVL FIRE®  to predict the cavitating injector flow accounting for cavitation mass transfer for changeable volume size domains. Moving needle (or plunger) is thereby considered to account for transient effects due to moving parts. Injected fuel is a mixture of two components (e.g. gasoline and ethanol), therefore each component will undergo mass transfer at different saturation condition.