Two-Stage 0D/1D Knock Model to Predict the Knock Boundary of SI Engines

Abstract

SI engines are typically designed to operate at the knock boundary, as engine knock limits their efficiency and thus further reduction of CO2 emissions. To consider this phenomenon in an engine process simulation, a precise knock model is needed. First, since auto-ignitions precede knocking events, the introduced 0D/1D knock model predicts when the unburnt mixture auto-ignites. For this, the model considers the two-stage auto-ignition of gasoline fuels, which occurs at specific boundary conditions, by calculating two Livengood-Wu-integrals. The model’s auto-ignition prediction is validated against measurement data of a single cylinder engine covering almost 3 000 knocking single working cycles at broadly varied operating conditions.