Working-cycle dissolved turbine efficiency with constant and pulse pressure boosting

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The working process of internal combustion engines induces a pulsating exhaust gas flow. This impacts the turbocharger sitting right behind the exhaust valves. The pulsation affects all relevant quantities at the turbine entry: ´pressure, mass flow and temperature. Usually turbines are applied based on steady state recorded maps. A real optimization occurs only at the engine and requires a lot of variants. Detailed, experiment based models of pulsating turbines, which support the application, are not available due to the lack of knowledge of the actual fluid state inside the turbine. Main reason therefore is the missing measurement equipment to characterize pulsating turbine flow. Simulations are not an option due to the high effort and the need for complete CAD data. In the frame of this project methods to characterize the engine typical flow through a turbocharger turbine will be investigated. A new measurement concept will be installed onto a hot gas test bench and will be validated in different manners (virtual temperature sensor probe, turbine dynamometer, CFD). Furthermore, the investigation will be bolstered by investigations on engine test benches and by engine process simulations. One main objective of the project is the determination of the transient values for: turbine pressure, turbine temperature, and mass flow rate and turbine torque. Based on these values and under consideration of transport terms the transient turbine efficiency can be calculated. This opens up new possibilities to evaluate the behavior of turbines und pulse admission. The knowledge and methods will then be applied on to two different turbine types of a turbocharger. Main objectives are new methods to describe the pulsating turbine flow of turbocharger and to gain new insight into the thermodynamic of the flow through a turbocharger and there by allow for an optimized application.