Spray Pattern Optimization for the Duratec 3.5L EcoBoost Engine

A systematic methodology has been employed to develop the Duratec 3.5L EcoBoost combustion system, with focus on the optimization of the combustion system including injector spray pattern, intake port design, piston geometry, cylinder head geometry. The development methodology was led by CFD (Computational Fluid Dynamics) modeling together with a testing program that uses optical, single-cylinder, and multi-cylinder engines. The current study shows the effect of several spray patterns on air-fuel mixing, in-cylinder flow development, surface wetting, and turbulence intensity. A few sets of injector spray patterns are studied; some that have a wide total cone angle, some that have a narrow cone angle and a couple of optimized injector spray patterns. The effect of the spray pattern at part load, full load and cold start operation was investigated and the methodology for choosing an optimized injector is presented. The preliminary dynamometer data obtained from a direct injection engine equipped with the optimized 6-hole injector indicated good mixing at part load and Wide-Open Throttle (WOT) operating conditions. Higher combustion efficiency and lower CO emissions at most operating points indicate better mixing for the DI engine than the baseline PFI engine. The optimized injector was able to demonstrate lower smoke emissions than the baseline injector.