Simulative Assessment of Injectors Placement and the Thermodynamic Effects of Gasoline Injection and Combustion in a Direct Dual Injection System

The paper concerns the analysis of the combustion and exhaust emission phenomena in a direct gasoline dual injection system of a SI engine for various symmetrical injector placement parameters in the combustion chamber. Achieving a good combustion process is shaped by the direct fuel injection process, whose parameters vary. The novel direct injection system, which deploys two direct injectors mounted symmetrically, was subjected to this simulative research. This article focuses on the aspect of spatial and angular position of injectors in order to perform injection and achieve fuel combustion. The injector's pseudo-optimal location has been presented along with several changed positions (3 values of injector inset: 0, 1 and 2 mm, 3 values of injector distance from the cylinder axis: 16, 17, 18 mm and 3 values of angle between injector and the cylinder axis: 42.5, 45 and 47.5 degrees - 27 combinations altogether). The research was conducted as a simulation experiment using AVL FIRE software. The best injector position was selected based on the fuel atomization, injection and combustion process indicators. The pseudo-optimal location, was characterized by: 1) the middle inset in the combustion chamber: y = -1 mm, 2) the highest value of the distance from the spark plug: z = 18 mm, 3) the highest angle in relation to the axis of the cylinder: alpha = 47.5 deg. The analysis of this impact results in the following conclusions: 1) the longitudinal change of the injector position is the most important value affecting changes in the fuel atomization and combustion indicators, 2) this change is about 1.5 times more significant than the change in the position of the injector's distance from the axis of the spark plug and about 4 times more significant than the angle of the injector's position.