3D CFD analyses are used to analyse the effects of port-injection of water in a high performance turbocharged GDI engine.
Particularly, water injection is adopted to replace mixture enrichment while preserving, if not improving, indicated mean
effective pressure and knock resistance. A full-load / maximum power engine operation of a currently made turbocharged GDI
engine is investigated comparing the actual adopted fuel-only rich mixture to stoichiometric-to-lean mixtures, for which water is
added in the intake port under constant charge cooling in the combustion chamber. In order to find the optimum fuel/water
balance, preliminary analyses are carried out using a chemical reactor to evaluate the effects of charge dilution and mixture
modification on both autoignition delays and laminar flame speeds. Thanks to the lower chemical reactivity of the diluted end
gases, the water-injected engine allows the spark advance (SA) to be increased; as a consequence, engine power target is met, or
even crossed, with a simultaneous relevant reduction of fuel consumption.