Large eddy simulations of transcritical e-fuel sprays using real-fluid multiphase flamelet-based modeling

Abstract

This study introduces a new numerical framework for the accurate simulation of transcritical reacting sprays using a multiphase, real-fluid, flamelet-based model. The transcritical flamelet library is combined with large-eddy simulations (LES) and rapid vapor–liquid equilibrium calculations in the context of a modern multiphase thermodynamic approach to explore vaporization dynamics, ignition characteristics, and soot formation. Current applications focus on the combustion of polyoxymethylene dimethyl ethers (OMEs), which are carbon-neutral e-fuels, in transcritical high-pressure configurations. Validation against experimental data shows a strong match in ignition delay and penetration lengths. The analysis of three OME₃– n-dodecane fuel blends reveals differences in evaporation, ignition, and soot production. Adding OME₃ to n-dodecane reduces soot production and shortens the liquid penetration length and ignition delay time. The findings highlight the importance of further investigation into the effects of transcritical states and fuel composition on combustion performance and emissions. Novelty and significance This work introduces a modeling technique for the use of transcritical counterflow flames in flamelet modeling, expanding the capabilities of large-eddy simulations with multiphase thermodynamics (LES-MT) to accurately modeling transcritical combustion. By incorporating real-fluid effects and two-phase interactions, the transcritical flamelet library provides a high-fidelity representation of the complex behaviors in high-pressure multiphase autoignition scenarios. This calibration-free approach can significantly improve our understanding of the transcritical combustion of emerging fuels such as OME₃ or their combination with traditional fuels such as n-dodecane.