Flame dynamics under various backpressure conditions were experimentally investigated using direct flame visualization, high-speed CH∗chemiluminescence imaging, and wall pressure measurements. The stagnation pressure and temperature used in the present study were 100 kPa and 2500 K, respectively, with a freestream Mach number of 4.5. Rectangular scramjet models with and without a cavity were used to explore the effects of the cavity on flame dynamics when operating in scramjet mode, ramjet mode, and unstart. The flow rate of the ethylene jet was varied to impose backpressures corresponding to each operation mode. For both models, reverse flame propagation was observed for ramjet mode and unstart. For ramjet mode, flame fluctuation occurred within the isolator due to the coupling of fluid dynamics and combustion. The presence of a cavity enhanced combustion and reduced flame fluctuation in both scram and ramjet mode. The cavity promoted unstart because of the greater heat release from combustion. Further research using spatially resolved diagnostic techniques is needed to identify the flame locations for ramjet mode and unstart.
|Number of pages
|Proceedings of the Combustion Institute
|Published - 2021
|38th International Symposium on Combustion, 2021 - Adelaide, Australia
Duration: 2021 Jan 24 → 2021 Jan 29
Bibliographical notePublisher Copyright:
© 2020 The Combustion Institute.
- Cavity flameholder
- Scramjet engine
- Supersonic combustion
ASJC Scopus subject areas
- General Chemical Engineering
- Mechanical Engineering
- Physical and Theoretical Chemistry