Flame stabilization and propagation in dual-mode scramjet with staged-strut injectors

To investigate the flame stabilization and propagation in a dual-mode scramjet with two-staged-strut injectors, a series of fuel dynamic adjustment experiments was conducted at the inlet Mach numbers of 2.0 and 3.0, and the corresponding inflow stagnation temperatures were 1231 and 1899 K, respectively. A linearly adjustable venturi was designed to realize the continuous control on the fuel mass flow rate. A 4000 frames/s high-speed imaging camera was used to record the flame structure during the combustion. The effects of the local equivalence ratio, the adjustment process of the fuel mass flow rate, and the inflow conditions on the combustor performance were experimentally analyzed. The results show that the flame can only be stabilizedin the recirculation region or two thin regions of the upstream strut under the lower inflow enthalpy condition, and the flame isblown out when the fuel flow rate is below the lean blowout limit. Comparatively, under the higher inflow enthalpy condition, an additional stabilized flame could be found in the boundary-layer separation region of the side walls, and the combustion waves were observed intermittently. The sudden changes in the wall pressure profiles and an obvious hysteresis phenomenon were found in the fuel dynamic adjustment procedure under the lower inflow enthalpy condition. However, the flame structure and corresponding wall pressure profile changed continuously, illustrating a much smaller hysteresis phenomenon under the higher inflow enthalpy condition.