Experimental Study on Flame Transition in a Two-Stage Struts Dual-Mode Scramjet

In this paper, flame stabilization and propagation inside a kerosene-fueled two-stage strut dual-mode scramjet combustor is experimentally investigated at Mach 2 and Mach 3 with the stagnation temperature of 958, 1,163, and 1,626°C (1,231, 1,436, and 1,899 K). A 2,000 frames/s high-speed imaging camera was used to record the flame structure during the combustion. The results show that when the scramjet is operating at lower stagnation temperatures of 958 and 1,163°C (1,231 and 1,436 K), the flame flashback equivalence ratio is much higher than the flame blowout limit, and the upstream strut can get a stabilized flame once it is reignited. A higher stagnation temperature and a lower inflow Mach number are advantageous to trigger flame flashback. When the scramjet is operating at a higher stagnation temperature of 1,626°C (1,899 K), continuous and oscillatory change of the flame and the axial wall pressure profiles were obtained.