Chemistry Mapping in Large-Eddy Simulations of Bluff-Body Flames Using Alternative Jet Fuels

In numerical combustion research, accurate chemical reaction mechanisms for heavy hydrocarbons are essential to investigate the flame dynamics of sustainable aviation fuels (SAF) relative to conventional jet fuels. However, accounting for hundreds or thousands of reactions makes finite-rate chemistry (FRC) large-eddy simulations (LES) impractical for realistic engineering scenarios. Here, a multidimensional chemistry coordinate mapping (CCM) approach is employed to reduce the computational expense of FRC-LES for jet fuel combustion. In the CCM methodology, the flow transport equations are directly integrated (DI) in the computational cells in physical space, whereas the chemical reactions are integrated in a phase space made up of a few principal variables, improving simulation efficiency. In a turbulent premixed bluff-body burner, the LES-CCM method is compared with experimental data and LES-DI results for conventional fuels Jet A (or A2) and JP5 (or A3) and alternative synthetic fuels, referred to as C1 and C5. The skeletal HyChem reaction mechanisms are utilized, ranging from 40 to 50 species and 200 to 300 reactions. A satisfying compromise is achieved between the accuracy of the results and the speedup factor, on average around three, depending on the CCM phase space dimension and the size of the reaction mechanism.