Optimization of IC Engine Design for Reduced Emissions using CFD Modeling

Abstract

Recent advances in computer CPU speed and engine model development make the use of multidimensional modeling increasingly attractive for engine designers and researchers seeking methods to reduce pollutant emissions, without sacrificing engine performance. Much progress has been made in engine submodel development in recent years, and modeling has been used to help explain aspects of engine performance and pollutant emissions trends. Factors including injection timing, injection pressure, injection rate-shape, combustion chamber design, boost pressure and EGR can now be explored computationally. A new development is the use of detailed models to help optimize engine design. With such a large number of engine parameters to investigate, it has been necessary to introduce efficient computational methodologies for the analysis of engine design configurations. Genetic-Algorithm-based (GA) search techniques have been demonstrated to be able to successfully follow a family of designs through a large search space to an optimum design. The GA method is applied together with multidimensional modeling in the present study to specify optimum injection rate-shape profiles for multiple injections in a heavy-duty diesel engine over a wide range of speeds and loads. In addition, related optimization studies are reviewed, including optimization of multiple injections with variations in EGR and boost pressure, optimization of intake flow swirl and tumble parameters for variable valve actuation applications, and optimization of the piston bowl geometry for a HSDI diesel engine.