Authorship：Lead author,　Corresponding author   Language：English   Publisher：Elsevier BV  

Opposed two-stage ramps lower the total-pressure loss of a hydrogen oblique detonation combustor, but ethylene ignites more slowly, and whether the gain survives the weaker shocks of two stages, and how far the operating limit depends on the mechanism, is not known. A single 19° ramp and opposed 10° + 10° ramps in a 200 × 40 mm duct with stoichiometric ethylene–air are compared at flight Mach 9.5 to 11 in two-dimensional inviscid simulations with a 34-species San Diego subset and USC Mech II. With the subset both ramps are stationary at Mach 10 to 11 and the two-stage ramp recovers 1.56 to 1.60 times the total pressure of the single ramp, more than for hydrogen, consistent with burning downstream of the contraction. At Mach 9.5 the two-stage ramp recovers 0.153, whereas the single-ramp reaction zone travels upstream at 190 m/s as the subsonic region grows. With USC Mech II the two-stage ramp does not ignite at Mach 9.5 and consumes 27% of the fuel at Mach 10. A zero-dimensional sequential-shock model reproduces the reaction position on the single-ramp wall path and two-stage centre-plane path to within about 2 mm with the subset at Mach 10 to 11, but near the limit places it 30 to 45 mm upstream with either mechanism; the computed pressure history removes most of this deviation on the centre plane only. The gain carries over to ethylene, but its lower Mach limit is constrained by second-stage ignition and fuel consumption, which depend on the mechanism.

DOI： 10.2139/ssrn.7648545

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：(MISC) Summary of the papers read (national conference and other science council)  

Authorship：Lead author   Language：Japanese   Publishing type：(MISC) Summary of the papers read (national conference and other science council)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society for Aeronautical and Space Sciences  

DOI： 10.2322/tastj.22.aj19

Authorship：Lead author   Language：English   Publishing type：(MISC) Summary of the papers read (national conference and other science council)  

Event date： 2026.10

Language：English   Presentation type：Oral presentation(general)  

Event date： 2026.4

Language：Japanese   Presentation type：Poster presentation  

Language：Japanese   Presentation type：Oral presentation(general)  

Language：English   Presentation type：Oral presentation(general)  

Language：English   Presentation type：Oral presentation(general)