Study of the hydraulic characteristics of two injectors fed with different fuels in a GDI system

In the latter years, the Gasoline Direct Injection systems (GDI) have been studied with the aim of providing a solution to the particulate matter emission issue. It has been proved that emission levels are reduced with the tuning of certain variables, such as the injection pressure, that affect the internal flow in the nozzle, which in turn plays an vital role in the spray development. On the other hand, the implementation of fuels such as alcohols and some surrogates shows potential for improving the engine performance and emissions because of the different physical properties of the fuels that can alter the mixture formation and the chemical properties that affect the combustion. In this work, an experimental study of the influence of different fuels on the internal flow is realized for a vast number of conditions, including those that promote flash boiling and strong collapse of the spray at different ambient temperatures and pressures. The fuels employed are three components of gasoline: iso-octane, n-hexane and n-pentane; ethanol; and two blends (E00 and E20) for two nozzle geometries. Two experimental techniques are used to measure the mass flow rate and momentum flux of the spray, and then characterize the flow inside the nozzle. The results show a similar injector behavior for all fuels, except for the ethanol, which shows an increase in the rate of injection and induces a hydraulic delay.