Experiment on ignition of kerosene injected from cavity floor in scramjet combustor with two-staged cavities were conducted at the inflow conditions of Mach number of 2.52

total temperature of 1486K

total pressure of 1.6MPa. The influences of injector diameter and injection position on ignition ability were analyzed. Results showed that when kerosene was injected from the upstream cavity floor using large diameter injector and ignited by the spark in the downstream cavity

it led to a reliable ignition with large margin of flame stability (kerosene overall equivalent ratio range of 0.102-0.206). The upstream propagation of pressure disturbance had an obvious hysteresis phenomenon and interacted with the formation of separating zone. The kerosene spray distribution was governed by the fuel injection scheme

and influenced the ignition characteristics on the other hand.