Characteristics of Flame Stabilization Enhancement in a Strut-Based Supersonic Combustor Equipped with Shock Wave Generators

Experimentaland numerical studies were conducted in a strut-based supersonic combustor. The inflow parameters Mach number, stagnation temperature, total pressure, and global equivalence ratio were 2.92, 1650 K, 2.6 MPa, and 0.25, respectively. Shock wave generators with different blockage ratios (BR) and dimensionless distances (ds/H) from the strut were used to enhance flame stabilization. On the premise of avoiding blockages, a larger blockage ratio can promote the expansion of the reaction zone and improve the flame stabilization ability. Increasing the dimensionless distance can provide more space for the expansion of the reaction zone. A long dimensionless distance (ds/H=0.5) requires a larger blockage ratio (BR=15%) to achieve flame stabilization. Three-dimensional simulations near the flame stability limit showed that the shock wave generators improve flame stabilization characteristics by generating adverse pressure gradients, low-speed regions, and accumulating fuel. The size of the recirculation zone downstream of the strut expands under the adverse pressure gradient. Besides, the expansion fan downstream of the shock wave generator suppresses the combustion process, which leads to the flame discontinuity phenomenon. As a result, the combustor with BR=15% and ds/H=0.500 has the largest recirculation zone and strongest combustion (combustion efficiency=82%).