Two skeletal kinetics mechanisms for reactive CH4/O-2 and H-2/O-2 ram accel
erator flowfields are presented. Both models were derived from a 190-reacti
on, 38-species kinetics mechanism (RAMEC or RAM accelerator MEChanism) that
successfully reproduces the high pressure (>50 atm), low dilution (110%),
fuel-rich chemistry of ram accelerator mixtures. The reduction procedure fo
r the CH4/O-2 mechanism utilized a detailed reduction technique with igniti
on delay time and heat release as the selection criteria. The methane-based
mechanism (REDRAM or REDuced RAM accelerator mechanism) contains 34 reacti
ons and 22 species and predicts ignition times to better than 5% and postco
mbustion temperatures to within 10 K of the full mechanism for a representa
tive range of ram accelerator mixtures and conditions. This CH4/O-2 mechani
sm is an improvement over existing reduced methane-oxidation mechanisms tha
t are based on lower-pressure, higher-temperature chemistry, An 18-step, 9-
species mechanism is presented for hydrogen based ram accelerator combustio
n that is based on the H-2/O-2 submechanism of the RAMEC/Gas Research Insti
tute GRI-Mech 1.2 methane oxidation mechanism, The H-2/O-2 kinetics model i
ncludes HO2 and H2O2 chemistry near the second and third explosion limits,
necessary for ignition at ram accelerator pressures but lacking in certain
finite rate chemistry models currently in use.