DEVELOPMENT AND MATCHING OF DOUBLE ENTRY TURBINES FOR THE NEXT GENERATION OF HIGHLY BOOSTED GASOLINE ENGINES

Abstract

Downsizing in combination with turbocharging represents the main technology trend for meeting climate relevant CO2 emission standards in gasoline engine applications. Extend-ed levels of downsizing involve increasing degrees of pulse charging. Separation of cylin-der blow downs, either with double entry turbines or valve train variability, is key for achieving enhanced rated power and low-end-torque targets in highly boosted four-cylinder engines.However, double entry turbines feature specific development challenges: The aerodynam-ic design via 3D CFD calculations presents a difficult task as well as the engine perfor-mance modeling and matching process in 1D gas exchange simulations. From a manufac-turing standpoint, casting of the turbine housing is complex especially for small displace-ment applications below 1.6 l due to e. g. thermo-mechanical boundaries.This paper demonstrates how to design and model double entry turbine performance characteristics within 1D gas exchange simulations, requiring special measured and pro-cessed turbine data, which is experimentally assessed on a hot gas test bench using a double burner setup. It is shown how the collective of the described development strate-gies can be used in assessing the potential of different turbine design concepts. This al-lows the turbocharger to be designed exactly to specific engine requirements.