Numerical study on the performance of a new integrated afterburner under a wide range of bypass ratio conditions

To improve the performance of the afterburner under a wide range of bypass ratio conditions, a new afterburner integrated with a mixer and a strut flameholder was proposed in this paper. The dry and thermal-state performance of the afterburner under different bypass ratio conditions were studied through numerical simulation with RANS CFD. The results showed that the mixing forms changed as bypass ratio increased. The integrated afterburner primarily achieved mixing by forming a recirculation region at the wake of the strut flameholder. As the bypass ratio increased, more vortices shed at the wake of the strut, increasing turbulent kinetic energy in the downstream area. This enhanced mixing between the inner and bypass gas flows, improved the thermal mixing performance, and increased total pressure loss. In the range of bypass ratio from 0.1 to 0.9, the mixing performance of the afterburner and total pressure loss both gradually increased with the increase of bypass ratio. When the bypass ratio was 0.55, the total pressure recovery coefficient was still more than 0.90, and the mixing performance reached 0.94. Following the rise in bypass ratio, the air from the mixer outlet in the integrated afterburner increased the oxygen content at the end of the strut, in the inclined cavity, near the center cone, and in the area of the wall flameholder, allowing more fuel to participate in combustion and thus improving combustion efficiency. When the bypass ratio was 0.50, the combustion efficiency was up to 0.954. However, as the bypass ratio continued to increase, the cold air from the mixer outlet impacted the pilot flame at the wake of the strut flameholder, reducing the degree of combustion reaction in the region and reducing the combustion efficiency.