A portable numerical model for the spray dynamics from GDI multi-hole injectors

A 3D model for the dynamics of sprays issuing from new generation multi-hole GDI injectors is presented, exhibiting novelty elements that increase portability to various injection conditions. An experimental investigation is carried out aimed at characterizing the behaviour of two different injectors, both manufactured by Bosch, a six-hole and a seven-hole one. Single pulse strategies are considered under non evaporating conditions: measured mass flow rates and cone angles are used as input variables for the numerical model, whereas measured penetration lengths and spray images are taken as terms of comparison for the obtained results. The model is assessed within the AVL FireTM code and preliminarily validated through a Simplex optimization algorithm with reference to the six-hole injector. Its validity in simulating the dynamics of the seven-hole injector is then demonstrated. The developed tool is suitable to be easily included within a multidimensional CFD code for the simulation of the in-cylinder thermo-fluidynamic processes, thus being of great relevance in the challenging task of achieving optimal charge conditions at all the engine loads and speeds.