Research on oscillation characteristics of pilot flame core region in a strut-equipped scramjet combustor

The experiments were conducted under the following conditions: flight Mach number 6, combustor inlet Mach number (Ma = 2.8), total temperature (T_t = 1680 K), and total pressure (P_t = 1.68 MPa). A ground direct-connection experiment was conducted using a supersonic rectangular combustor with 6 mm thin-strut stabilization. To investigate the influence of strut equivalence ratio on oscillation characteristics of the pilot-core at the strut trailing edge, and to reveal the interaction mechanisms between pilot-core oscillations and global flame dynamics, this study conducted ground direct-connect ignition experiments. Through systematic analysis of flame images captured by high-speed camera and combustor wall pressure data acquired from pressure transducer, distinct oscillation patterns of the pilot-core were identified under varying equivalence ratio conditions. At ER = 0.25, the pilot-core maintains a stable area but exhibits periodic splitting and merging dynamics in morphology, with minimal influence on the global flame area. When ER increases to 0.42, the pilot-core retains a bifurcated dual-pilot-cores configuration while demonstrating periodic blow-off-reattachment cycles at the strut trailing edge. The blow-off events lead to reductions in global flame area. In contrast, at ER = 0.67, the system transitions between alternating strong–weak pilot-core oscillation modes. The strong pilot-core enhances flame stability by suppressing upstream flame propagation.