Large Eddy Simulation of Ammonia/Methane Jet Flames Using Tabulated Chemistry

Ammonia (NH₃) is gaining prominence as a carbon-free fuel, but its low flame speed, long ignition delay, and higher nitric oxide (NOₓ) formation present significant combustion challenges. Blending methane (CH₄) with NH₃ improves flame reactivity and stability, offering a transitional pathway toward carbon-neutral combustion systems. The present study focuses on investigating the flame characteristics of NH₃/CH₄ blends in a single burner furnace using large eddy simulation (LES) coupled with flamelet generated manifold (FGM). Thermochemical properties are tabulated with mixture fraction, progress variable, variance of progress variable, and total enthalpy derived from the one-dimensional flamelet solutions using the modified Okafor mechanism (Kovaleva et al., Fuel Communications, 10, 100054). The numerical simulations are carried out at various equivalence ratios and primary/secondary air ratios. The results demonstrate the present LES-FGM captures the trend of major (O₂ and CO₂) and minor species variation with a reasonable agreement against the experimental data. The flame stabilization, temperature distribution, and pollutant (NOx and CO) formation are further analyzed. The insights of this work extend our understanding in designing low-carbon ammonia-based combustion systems using high-fidelity simulations.