Multi-parameter mechanistic study on the influence of vaporizer fuel atomization characteristics on combustor ignition and flame propagation processes

To address light-round failure during ignition in the vaporizer combustor of micro and small gas turbine engine (MS-GTE), this study investigates the effects of multiple parameters on atomization characteristics using PDPA and shadowgraphy. The results indicate that the inward contraction of spray distribution promotes flame propagation within a single vaporizer but hinders it between adjacent vaporizers. Increasing the exit diameter improves turbulent shear and fuel mist distribution while reducing SMD at the spray boundary. Circumferential holes at the exit induce localized wall-attached vortices that expand spray coverage outward while reducing SMD and mitigating inward spray contraction. Higher air pressure differential promotes continuous-phase breakup and spray expansion. Elevated wall temperatures enhance atomization, though this improvement tends to saturate at higher levels. Furthermore, ignition and light-round experiments were conducted using a three-sector combustor with high-speed imaging to validate the atomization findings. Vaporizers with larger exit diameters improve atomization uniformity and fuel mist dispersion, enabling shorter ignition and light-round timing at lower fuel-air ratios. The circumferential holes expand fuel mist dispersion, filling fuel vacuum regions between adjacent vaporizers and significantly enhancing ignition and light-round performance. The dominant mechanisms in each phase determine how various vaporizer configurations influence ignition and light-round behavior.