变结构RBCC发动机亚燃模态全流道数值模拟研究

The use of a structurally variable combustor is one of the most effective methods to improve the performance of a rocket-based combined-cycle (RBCC) engine over a wide operating range. Aims to study the matching between the combustor and the inlet/exhaust of a variable geometry RBCC engine at low inflow Mach numbers via full flow path of three-dimensional numerical simulations. Furthermore, focus on the feasibility of using a variable geometry combustor to carry out a steady secondary fuel combustion organization in ramjet mode. Under the inflow condition of Ma=3, the engine performances were studied based on the rocket-ramjet and pure ramjet combustion mode, and the transition of the engine from the rocket-ramjet mode to the pure ramjet mode was obtained in the variable geometry ram combustor. Concluding remarks are summarized as: (1) In the rocket ramjet mode, the primary rocket has obvious positive effects on improving the secondary fuel combustion efficiency and results in a higher ramjet specific impulse. Matching of the combustor and inlet/exhaust has been realized under the rocket-ramjet mode. (2) In the rocket ramjet mode, improvement of the engine performances prefers a concentrated fuel injection rather than a dispersed injection through isolator section and pylons. In the pure ramjet mode, the specific impulse of the full flow path increases by 14.5%, compared with in the rocket-ramjet mode, despite the decrease of ram specific impulse by 10.2% due to a worsen combustion efficiency.