Experimental and numerical investigations of a novel vortex-controlled flameholder for advanced aeroengine combustors

• Different cavity sizes affect flameholder combustion stabilization. • Larger flameholders increase the recirculation zone and local fuel-air ratio. • A horseshoe-shaped primary vortex characterizes the flow field. • The flame stability of the flameholder improves as the cavity length increases. Recent research has demonstrated that the vortex-controlled flameholder (VCF) is a promising strategy for advanced aircraft afterburners to achieve robust flame stability and high combustion efficiency with a wide range of operating conditions. This study serves as a follow-up study aimed at elucidating the influence of VCF cavity size on flow and combustion characteristics. The VCF configurations examined in this study include cavity lengths of 40 mm (case-1), 55 mm (case-2), and 70 mm (case-3). Both experimental and numerical simulation investigations are employed to assess the flow field, lean ignition/blowout limits, flame propagation characteristics, and temperature distributions across the three case configurations at temperatures ranging from 400 to 500 K. Research shows that cavity length significantly influences the size of the cavity-trapped vortex, local fuel-air ratio (FAR), and turbulence intensity. Longer cavities increase vortex size and local FAR while decreasing turbulence intensity. Moreover, ignition at 400 K was successfully achieved at a cavity length of greater than 55 mm. At 500 K, shorter cavities required two high-energy flame kernel inputs, while the longer cavity needed only one. As the length reached 70 mm, the VCF achieves the shortest ignition time and smallest ignition FAR. Meanwhile, increasing cavity length improved combustor fuel reaction and outlet temperature.