Modeling of a map based turbocharger in a three dimensional engine environment

The ongoing trend towards downsized engines with turbocharger intensifies the need for development tools capable of simulating complex engine layouts with a level of details that only multidimensional models offer. This is strongly driven by stringent emission limits and the effort to reduce CO2 emissions while ensuring the concurrently demanded vehicle performance. In turbocharged engines the coupling of the combustion chamber and turbocharger forms a complex system in which the components influence each other remarkably causing e.g. the well-known turbo-lag.3D-CFD simulations of cylinders with parts of the runner or airbox have become practicable several years ago and will remain a valuable tool in virtual engine development; however the next logical step is to extend this approach from the cylinder to the full engine domain. This paper presents an approach that combines a three dimensional representation of the entire engine, including the complete air path, with a 0D-turbocharger.The approach, is used to model a two-cylinder engine which is compared to measurements from the test bench. The interaction between turbocharger and engine within a working cycle is analyzed under constant load conditions. The benefits of the chosen approach are highlighted by comparing it to a conventional approach of using one dimensional pressure traces as boundary conditions.