Effect of inlet rotation angle on lean ignition and blowout limits of an integrated afterburner

Abstract

This study investigates the effects of inlet rotation angle on the lean ignition and blowout characteristics of an integrated afterburner under high-temperature rotating inflow conditions. Ignition and blowout experiments are conducted in an integrated afterburner with a single strut-cavity structure. The lean ignition and blowout fuel–air ratios are measured at strut trailing-edge Mach numbers ranging from 0.20 to 0.35 and rotation angles from 0° to 15°. Numerical simulations are also performed to analyze the effects of inlet rotation angle on the flow field structure, fuel atomization and mixing, and combustion characteristics. The results show that: 1) as the inlet rotation angle increases, the lean ignition and blowout fuel–air ratios follow a nonmonotonic trend, initially decreasing and then increasing, with optimal performance occurring at a rotation angle of 5°; 2) a small rotation angle enhances flame retention within the recirculation zone, promotes secondary fuel atomization and mixing, and improves local combustion conditions; 3) a larger rotation angle weakens the recirculation zone downstream of the strut, shifts the shear layer outward, and increases local heat dissipation, raising the risk of flame blowout. This study provides a valuable reference for optimizing combustion organization and designing stable lean-blowout combustion in integrated afterburners.