The "Axial turbine turbocharger for lean-burn concepts" project is concerned with the development and experimental testing of a single-stage axial turbine turbocharger for turbocharging a petrol engine operated with λ = 2 in the area of the Worldwide Harmonized Light-Duty Vehicles Test Cycle (WLTC). The numerical development of the axial turbine of the turbocharger in the predecessor project "Exhaust gas turbocharger for lean concepts" serves as the starting point for the project. The issue is being addressed as a cooperation between the Institute of Turbomachinery and Fluid Dynamics at Leibniz Universität Hannover and the Institute of Internal Combustion Engines at Technische Universität Braunschweig over a period of two years.
Funding period:
Axial turbine ATL for lean concepts: 01.04.2022 - 31.03.2024
Infrastructure for future hydrogen drive technology (I-ZWAT): 01.03.2022 - 31.07.2022
In recent years, CO2 limits have been steadily tightened. Various technologies have been developed to meet these requirements. One of these technologies is the downsizing of petrol engines. Air dilution increases the indicated engine efficiency and reduces fuel consumption. However, lean combustion has an impact on the exhaust gas properties and thus on the exhaust gas turbocharger (ATL). This creates direct interfaces with the ICE2025+ and ICE2030 projects. Such a turbocharging unit is essential for the overall efficiency of an internal combustion engine and is what makes lean-burn operation possible in the first place.
In lean operation, the operating range limits of single-stage ATL limit the lean operating range in the engine map. To solve this problem, a single-stage system is being developed numerically in the "ATL for lean concepts" project in order to cover the WLTC-relevant operating range with λ=2. An innovative axial turbine concept for automotive applications with an axial-radial diffuser in combination with variable turbine geometry and variable compressor inlet cross-section shows promising results. Based on this, the potential of the system in engine operation will be demonstrated in the follow-up project "Axial turbine ATL for lean concepts".
First, a multi-objective optimization of the compressor is carried out in collaboration with the cooperating institute based on input data from engine process simulations. In parallel, the developed ATL is manufactured and validated on a hot gas and engine test bench. A λ=1 engine is being expanded to include a lean-burn process. For this purpose, the addition of hydrogen is used to extend the ignition limits of the gasoline-air mixture. Finally, the optimized compressor is manufactured and validated on the hot gas test bench. Finally, the compressor maps are used to provide a simulative outlook on the lean limit achieved in the engine simulation environment.
The necessary hydrogen infrastructure, which enables the lean operation of the engine, is being financed within the "Infrastructure for Future Hydrogen Propulsion Technology (I-ZWAT)" project from the European Regional Development Fund (ERDF) as part of the Union's response to the COVID-19 pandemic.