3D CFD Upfront Optimization of the In-Cylinder Flow of the 3.5L V6 EcoBoost Engine

This paper presents part of the analytical work performed for the development and optimization of the 3.5L EcoBoost combustion system from Ford Motor Company. The 3.5L EcoBoost combustion system is a direct injected twin turbocharged combustion system employing side-mounted multi-hole injectors. Upfront 3D CFD, employing a Ford proprietary KIVA-based code, was extensively used in the combustion system development and optimization phases. This paper presents the effect of intake port design with various levels of tumble motion on the combustion system characteristics. A high tumble intake port design enforces a well-organized stable motion that results in higher turbulence intensity in the cylinder that in turn leads to faster burn rates, a more stable combustion and less fuel enrichment requirement at full load. Several intake ports were designed and analyzed to investigate the effects of tumble level, intake valve masking, injection timing, and injector flow rate on flow characteristics, air-fuel mixing, turbulence intensity, and surface wetting at part load and full load operating conditions. A medium tumble port and a high tumble port were tested on the dynamometer and engine data is presented that shows that the higher tumble port mitigates knock and improves combustion stability due to the coherent flow structures that it generates.