Numerical simulation of the interaction between shock trains and flame in hypersonic crossflow for various fuels

Ethylene (C₂H₄) and hydrogen (H₂), serving as crucial intermediate species in hydrocarbon oxidation and pyrolysis processes, constitute practical propulsion system fuels. This paper conducted an analysis of the typical flow field structures, combustion characteristics, and performance of scramjet engines operating under high Mach number inflows with H₂/C₂H₄ fuel combustion. The numerical methodology incorporates a 9-species, 27-step H₂/O₂ chemical kinetics mechanism and an 8-species, 10-step C₂H₄/O₂ reaction scheme, implemented with wall function formulation and k-ω shear-stress-transport turbulence model, utilizing Reynolds-averaged Navier-Stokes computations, demonstrating excellent correlation with experimental measurements. The results show that (1) compared with H₂ fuel, the shock wave in C₂H₄ fuel combustion flow field is more pronounced, and the Mach number decreases more slowly along the flow direction. (2) The spatial distribution patterns of engine heat release zones and premixed/non-premixed combustion modes under supersonic crossflow conditions were obtained, with H₂ fuel showing larger premixed combustion zones in the boundary layer upstream of the combustor than C₂H₄, while other combustion areas were non-premixed. (3) Comparative analyses of stagnation pressure losses along the flowpath revealed that C₂H₄ combustion exhibits greater total pressure loss and lower combustion efficiency than H₂, while generating approximately 70% higher thrust output. The research results provide important basis for further detailed flow field calculation and multi-scale combustion process research under high Mach number incoming flow conditions.