To investigate the ignition characteristics of three liquid fuels (aviation kerosene (RP-3)

high thermal oxidation stability fuel (RP-3+100)

high-density liquid hydrocarbon fuel (LUAN))

high-altitude ignition simulated experiment in a small-scale ramjet combustor was conducted. The results showed that the three fuels can be ignited successfully under all selected conditions. With the increase of temperature and pressure of inlet air

the range of ignition equivalence ratio of three fuels became wider. But the increased velocity narrowed the range of ignition equivalence ratio. The range of ignition equivalence ratio of RP-3+100 was the widest among the three fuels at any time. RP-3 and LUAN had a similar range of ignition equivalence ratio. As the extraneous factors

like temperature

pressure

and velocity

changed

RP-3+100 had the narrowest variation of the range of the ignition equivalence ratio

while RP-3 was the widest one.