Optimizing the calibration of a turbocharged GDI engine through numerical simulation and direct optimization

Different optimization strategies for the optimization of the calibration of a turbocharged GDI engine through numerical simulation were analyzed, aiming to evaluate the opportunities offered by direct optimization techniques. A one-dimensional fluid dynamic engine model was used to predict engine performance, taking into account knock and exhaust temperature constraints. Air fuel ratio, spark advance, boost pressure and cam phasing were optimized by means of different optimization strategies, including direct search as well as numerical methods. Both full load (with maximum bmep targets) and part load (with minimum bsfc targets) were considered. The potential for remarkable improvements (up to 10% bmep increase at full load and 8 g/kWh bsfc decrease at part load) in comparison with the baseline engine calibration was highlighted, and a ranking between different optimization methods was obtained, based on the requested computational efforts and on their capabilities to handle constrained optimization problems.