Reaction mechanism reduction for ethylene-fueled supersonic combustion CFD.

CHEMKIN-Pro was used to build a custom-made reduced reaction mechanism for a 3D simulation of C₂H₄/Air reaction in a supersonic combustion ramjet (scramjet) combustor for the JAXA S-520-RD1 flight test performed on 24 July 2022. It was also attempted to reproduce the effect of unavoidable H₂O vitiation in the facility (ground) test on combustion characteristics. USC Mech II (a 111-species mechanism) was applied as the master mechanism. First, 1D simulation was conducted by applying a plug flow reactor model; 34-, 23-, 20-, 18-, and 19-species mechanisms were suggested as candidates for reduced mechanism. Then, 0D ignition delay simulation by applying a perfectly stirred reactor model by CHEMKIN-Pro, 2D reacting flow simulation by CRUNCH CFD, and 3D reacting flow simulation by RANS were performed to select the most suitable reduced mechanism. The 20-species (96-elementary-reactions) mechanism consisted of H₂, O₂, N₂, H₂O, CO₂, CO, H, O, OH, HO₂, CH₂, CH₂^*, CH₃, HCO, CH₂O, CH₃O, C₂H₂, C₂H₃, C₂H₄, and CH₂CHO and was selected as the best-reduced reaction mechanism for C₂H₄-fueled 3D simulation under the flight and facility conditions corresponding to the RD1 flight test. [ABSTRACT FROM AUTHOR]