Effect of primary jet position on the ignition characteristics of a single vortex combustor

The single vortex combustor (SVC) has gained increased attention in small-scale aero engines due to its enhanced combustion stability and structural simplicity. Despite its advantages, the fundamental mechanisms governing flame kernel propagation and stabilization during ignition process remain poorly understood. This study combines systematic experiments and numerical simulations to investigate the effect of the primary jet axial position on ignition performance. Five SVC configurations are analyzed to correlate ignition boundaries and visualized flame kernel propagation with the underlying vortex structures and recirculating flows. High-speed flame imaging identifies three distinct ignition stages: initial kernel propagation, kernel survival, and final flame growth. Results demonstrate that positioning the primary jet upstream significantly enhances ignition performance by shortening the initial and final stages. This upstream shift establishes a more favorable flow field, characterized by higher velocities near the igniter and a stronger recirculating flow that optimizes the propagation pathways of the flame kernel. Consequently, this strengthens the kernel propagation capability and substantially minimizes the extinction risk for the flame kernel. These findings offer quantitative guidelines for designing more efficient and reliable SVCs for improved ignition performance.