关键词: 超燃冲压发动机；双模态；多凹腔；燃料喷注

Abstract: A series of direct connected tests of the multi-cavity dual-mode scramjet operated in a simulated flight number range of 4.5 ~ 5.0 and a total temperature range of 1048 ~ 1231K were carried out for a further understanding of how the fuel injection strategy affected the flow field structure and the performance of the engine. Steady wall static pressure and outlet total pressure were obtained during the experiments with different fuel injection equivalence ratio，injection position or injection stages. The experimental data was particularly processed and analyzed with the one-dimensional impulse analysis program. According to the results，the thrust of the engine effectively increased as the equivalence ratio is enhanced，but both the combustion efficiency and the specific impulse of the engine are synchronously decreased. The combustion efficiency and the thrust increared 5.6% and 4.4%，respectively，by moving the fuel injection position forward. The flow field structure is obviously influenced by the fuel injection distribution. The more fuel is injected from the downstream cavity，the farther downstream the thermal throat is located. And much more heat is required to form the thermal throat. When the fuel is injected from the upstream cavity and downstream cavity，a wide subsonic region which is to the benefit of the combustion and heat releasing of the fuel is formed. The combustion efficiency and the thrust of the engine increased by 10.4% and 10.8%，respectively，with this strategy.

Key words: Scramjet；Dual-mode；Multi-cavity；Fuel injection