Research on the flame oscillation characteristics of scramjet combustor equipped with strut fuel injector.

The combustor is the core component of the scramjet engine, and stable combustion is the prerequisite for the efficient operation of the scramjet engine. This paper investigates combustion stability in a combustor with a thin strut for oxygen supplementation at the trailing edge. LES (Large eddy simulation) was carried out under the combustor inlet conditions of Ma = 2.8, T t = 1680 K, and P t = 1.87 MPa. The results show that as the amount of oxygen supplementation inside the combustor increases, the oscillation forward propagation characteristics of the flame front inside the combustor are formed. First, the combustion instability phenomenon of the flame inside the combustor is analyzed, and then the oscillation frequency of the flame is analyzed by FFT (Fast Fourier Transform) of the flame front and pressure and DMD (Dynamic Mode Decomposition) of the velocity field within one cycle. Finally, the flame forward propagation mechanism inside the combustor is analyzed by pressure-velocity-heat release distribution. The results show that the injection of excess oxygen inside the combustor forms a strong coupling phenomenon of flow and combustion, and the premixed gas downstream of the trailing edge of the strut forms a state of slow combustion to explosion, forming a flame propagation forward and periodic oscillation phenomenon. • LES method is used to capture the flame oscillation behavior with different oxygen supplementation. • The multi-frequency characteristics of combustion oscillations are obtained by using spectrum analysis. • Different combustion modes in flame oscillation and stable regions are discussed. • The mechanism of flame oscillation and propagation upstream is discussed. [ABSTRACT FROM AUTHOR]