Fuel temperature influence on the performance of a last generation common-rail diesel ballistic injector. Part II: 1D model development, validation and analysis

Abstract

A one-dimensional model of a solenoid-driven common-rail diesel injector has been developed in order to study the influence of fuel temperature on the injection process. The model has been implemented after a thorough characterization of the injector, both from the dimensional and the hydraulic point of view. In this sense, experimental tools for the determination of the geometry of the injector lines and orifices have been described in the paper, together with the hydraulic setup introduced to characterize the flow behaviour through the calibrated orifices.

An extensive validation of the model has been performed by comparing the modelled mass flow rate against the experimental results introduced in the first part of the paper, which were performed for different engine-like operating conditions involving a wide range of fuel temperatures, injection pressures and energizing times. In that first part of the study, an important influence of the fuel temperature was reported, especially in terms of the dynamic behaviour of the injector, due to its ballistic nature. The results from the model have allowed to explain and further extend the findings of the experimental study by analyzing key features of the injector dynamics, such as the pressure drop established in the control volume due to the control orifices performance or the forces due to viscous friction, also assessing their influence on the needle lift laws.