Abstract:
Scramjets are regarded as one of the most efficiency air-breathing propulsion devices in supersonic flight conditions, and combustors are critical components in scramjet engines. In supersonic combustor, the velocity of the main airflow is of an order of kilometers per second, and in such a harsh flowing condition, the combustion organization and flame stabilization are extremely hard to be achieved. To solve the issues about flame holding and combustion efficiency improving, it is necessary to have a deep understanding in the flame characteristics, based on which, the further optimization could be carried out. In supersonic combustor, the flame characteristics including the flame mechanism characteristic and the flame propagation characteristic should be paid more attention. This paper aims to provide a review on flame stabilization and flame propagation characteristics in supersonic combustor to help the researchers easily working on supersonic combustion with their further work. At first, the difficulty on the flame stabilization is discussed, including the higher airflow velocity and lower fuel resident time in the combustor. Furthermore, the flame characteristic in supersonic combustor in two kinds of main flame stabilization modes, namely the cavity and the strut, are summarized, and the advantage of strut in fuel injection and fuel mixing performance is set forth. The flame stabilization criteria are also presented and analyzed. Then, the methods of flame stabilization, including enlarging the fuel resident time and shortening the fuel reaction time, are also reported, and the mechanism of flame stabilization in different flame holding schemes are analyzed. The O
2-pilot strut designed by Harbin Institute of Technology is focused on, and the dynamic characteristics, including flame propagation and flame oscillation characteristics, are analyzed. The flame propagation characteristic in strut/wall combined fuel injection mode is discussed. Based on this paper, the improved scheme of combustion performance is given to provide a reference for the further investigation.