燃烧室前缘扩张角对旋转爆震冲压发动机的影响

针对圆柱形隔离段-燃烧室构型的旋转爆震冲压发动机,开展了总温为860 K、马赫数为2的来流条件下的直连式试验,探讨了燃烧室前缘扩张角(θ=30°,45°,60°,90°)对爆震波传播特性、工况范围及压力分布的影响。结果表明:当燃烧室前缘扩张角为90°时,燃烧模态均为爆燃燃烧；随着扩张角的减小,燃烧模态将会向锯齿波和混合模态(包含单波阶段)转换。当燃烧室前缘扩张角为30°时,旋转爆震的自持工况范围最宽且燃烧室压力最高；同时,随着燃烧室前缘扩张角减小,实现混合模态的当量比下限降低。此外,分析了燃烧模态对来流的影响,发现:锯齿波/混合模态燃烧室内存在的周期性高频压力扰动会使隔离段内的激波串位置前移；混合模态对超声速来流的影响最为显著。

Effect of combustor leading edge expansion angle on rotating detonation ramjet

A series of direct-connected tests were conducted on a rotating detonation ramjet with a cylindrical isolator-combustor configuration, under the conditions of a total temperature of 860 K and Ma=2 inflow. The influence of the combustor leading edge expansion angle(θ=30°,45°,60°, 90°) on the propagation characteristics, operating range, and pressure distribution of detonation waves was investigated. The results indicate that the combustion mode is consistently deflagration when the expansion angle of the leading edge of the combustor is 90°. As the expansion angle gradually decreases, the combustion mode transitions towards sawtooth and hybrid mode (including single wave stage). When the expansion angle of the leading edge of the combustor is 30°, the rotating detonation exhibits the widest self-sustaining operating range and highest combustor pressure. Additionally, as the expansion angle decreases, the lower limit of the equivalence ratio for achieving the hybrid mode decreases. At the same time, the impact of combustion modes on the inflow was analyzed and it was found that the periodic high-frequency pressure oscillation in the sawtooth wave/hybrid mode combustor could cause the positioning of leading edge of the shock train in the isolator to move upstream. The hybrid mode has the most significant impact on supersonic inflow.