3D-CFD-Based optimization of piston Geometry, injector nozzle Design, and injection strategy for the alternative diesel fuel Oxymethylene ether (OME)

Oxymethylene ethers (OMEs) represent a promising alternative to conventional diesel fuels, offering carbon–neutral mobility and soot-free combustion due to the absence of carbon–carbon bonds. This prevents the soot-NO_x trade-off. Moreover, an OME-adapted and optimized combustion process offers the opportunity to improve engine efficiency while simultaneously reducing NO_x emissions, thus addressing the existing efficiency-NO_x trade-off. Realizing this potential necessitates tailoring the mixture preparation and combustion process to the unique characteristics of OME. This study explores the optimization of piston geometry, injector nozzle design, and injection strategies to leverage OME's unique properties for improved engine performance. Using 3D-CFD simulations with the CONVERGE software, key parameters such as nozzle diameter, spray angle, and piston bowl shape are analyzed for their impact on efficiency and emissions. The results highlight that wider piston bowl geometries enhance indicated efficiency, while larger nozzle diameters improve combustion efficiency due to reduced combustion durations. Smaller spray angles effectively lower NO_x emissions but introduce challenges such as piston wetting and localized temperature peaks. The study also confirms that pilot injection does not benefit OME operation, simplifying injection system requirements. These findings underline the need for tailored engine designs to fully exploit OME's potential as a sustainable fuel. The proposed configurations pave the way for further experimental validation and practical implementation in internal combustion engines, contributing to the global transition toward low-carbon transport systems.