Investigation of supersonic combustion dynamics via 50 kHz CH∗ chemiluminescence imaging

The mean heat release characteristics and the dynamic flame behavior occurring within a high-speed premixed ethylene/air combustion environment was studied using high-speed (50 kHz) CH∗ chemiluminescence imaging in a fully premixed cavity- stabilized combustor. The mean CH∗ chemiluminescence which is a representative marker of the heat release from the flame exhibited a spreading angle of 9.5° and the leading edge of the flame was stabilized near the mid- point of the cavity. Fluctuations in the flame brush width resulted in cyclical oscillations in the flame spreading angle which can vary more than 10° over a short (oscillating) time period. The strongest peaks of both the CH∗ signal and flame brush width occur at 340 and 280 Hz which characterize the global unsteadiness of the combustor