Performance of supersonic combustors with fuel injection in diverging section

Performances of combustor with fuel injection in the diverging section were experimentally investigated in a direct-connect wind tunnel facility at Mach 2.5 and freestream total temperature of 1500 K. The baseline combustor had a diverging section (A = 1.08 ~ 2.35 × combustor inlet area (A i )) with a fixed diverging half angle of 3.1 degrees, and three sets of injectors at A = 1.33, 1.59, and 1.84 × A i . A portion of the diverging section (1.18 ~ 1.72 × A i ) was replaced with ones with 1.55 or 6.2 degrees diverging half angle, with injector orifices at 1.59 × A i . Room temperature hydrogen was injected at sonic speed through perpendicular orifices, and characteristic flow parameters such as peak pressure rise, expansion pattern, and interaction length were examined. Using one-dimensional analysis, combustor performances such as combustion efficiency and thrust production due to fuel injection and combustion was evaluated. As results, it was found that fuel injection within the diverging section can result in as high performance as that within the constant area section, and has possibility to reduce or eliminate the required length of the isolator section.