Performance and Emissions of an Advanced Multi-Cylinder SI Engine Operating in Ultra-Lean Conditions
Along the design process of a new engine, the calibration phase at the test bench usually involves a relevant percentage of the overall time-to-market. Each control variable, in fact, needs to be properly selected to optimize the performance and emissions, complying with thermal and mechanical stresses limits of the engine. This issue is still more critical for advanced engine architectures, which include additional control variables, such as valve phasing, turbocharger control, EGR level, etc. The aim of this work is the development of a numerically performed calibration procedure, applied to a prototype multi-cylinder Spark Ignition (SI) engine, designed to operate at very lean mixtures. To this aim, an active Pre-Chamber ignition system is considered. The required air flow rate is indeed provided by a Low-Pressure (LP) variable geometry turbocharger group, coupled to a high-pressure e-compressor.