Reaction mechanism reduction for ethylene-fueled supersonic combustion CFD

Abstract

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.