Numerical Simulation of Multi Injector Cylinder Head Engine Concept Enhancing Fuel Atomization

The insufficient level of atomization of the fuel drops in direct-injection engines is a major cause of pollutant emissions because of the incomplete combustion process. The fuel injection is a critical part of the homogeneous air-fuel mixture. It is well known that higher injection pressure enhances the atomization of the fuel; however, there are physical and technological limits to go further in this regard. Previous work was focused mainly on the swirl created by the spray flow, and on the avoidance of fuel drops coalescences and their impingement on the cylinder walls. This current paper proposes a new approach to reduce the diameter of the atomized fuel drops by colliding the fuel sprays in a cylinder arranged with 4 opposed injectors, in order to increase the breakup of the atomized fuel drops and therefore, to improve the homogeneity of the air-fuel mixture. This effect is estimated by means of CFD (Computational Fluid Dynamics) simulations with OpenFOAM®, under non-reacting and reacting conditions of the fuel. The results show a reduction of the atomized fuel drops by more than 25% compared to an engine equipped with a single injector. The goal is to standardize the numerical and computational models of this concept, to be applied in the next stage on big and low-speed diesel engines having more space to locate injectors radially to the cylinder, providing the growth of the potential of this kind of engines and eco-friendly energy generation.