Fundamental optical and numerical investigation of pre-chamber ignition in IC engines

• Applicant: Professor Dr. Andreas Dreizler
• Subject Area: Energy Process Engineering ; Hydraulic and Turbo Engines and Piston Engines
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 579050539

Pre-chamber spark plugs are a key technology for enabling highly efficient and low-emission spark ignition engines with lean-burn technology for the future. Igniting a fuel-air mixture in a small pre-chamber creates hot, turbulent jets. These enter the combustion chamber and initiate rapid and stable combustion, even with extremely lean mixtures. This so-called turbulent jet ignition enables higher efficiencies and the use of climate-neutral fuels with low flame speeds. At the same time, the stability of combustion is improved. Current research shows that turbulent jet ignition has considerable potential to increase efficiency. Numerous studies have investigated how geometry, boundary conditions and fuel type influence efficiency and emissions. Nevertheless, the interaction between local turbulence, mixture formation and wall heat losses, particularly in the orifices between the pre-chamber and the combustion chamber, remains poorly understood. These processes are, however, crucial to how the mixture is ignited in the combustion chamber. This raises the question of whether the flame propagates from the pre-chamber into the combustion chamber, or whether it is extinguished in the bores and then auto-ignites due to the hot jet. Understanding these processes is essential for developing reliable ignition systems for future fuels and for expanding the engine's operating range. The project's main objective is to develop a thorough understanding of the underlying thermochemical and fluid dynamic processes, as well as how they interact, in turbulent jet ignition. To this end, detailed experimental investigations using high-resolution optical diagnostics are planned on three complementary optical test benches. These range from an optically accessible pressure chamber with an optically accessible pre-chamber to an optically accessible engine with a pre-chamber spark plug similar to those used in series production. While the simplified setups enable detailed analysis, the realistic systems allow conclusions to be drawn about practical applicability. Numerical simulations accompany the experiments to make non-measurable parameters accessible, support detailed analysis, and make the results available in the form of validated models beyond this project. The aim is to derive general principles and dimensionless parameters that are independent of specific geometries or boundary conditions, and which describe the ignition mechanisms.

• DFG Programme: Research Grants
• International Connection: Switzerland
• Cooperation Partners: Professor Dr. Kai Herrmann; Dr. Yuri Wright