Abstract A widely applicable and variable geometry 2-D rocket based combined cycle (RBCC) inlet characterized by the dual-duct design is conceptually put forward. The inlet operates as dual-duct status in the low Mach range (0~4), and transits to single-flowpath status in the following high Mach range (4~7). It accomplishes operational status transition through an 8.0-degree ramp rotation and a 4.0-degree cowl rotation at Mach 4. Through numerical simulations on typical flight Mach numbers, the observed starting Mach number is 2.2, which provides a sufficient operational window for a smooth ejector-to-ramjet mode transition. The RBCC inlet achieves comprehensive high mass capture coefficients in the overall wide flight range, especially in the low speed regimes. Suitable Mach numbers satisfying various combustion requirements in different modes together with high total pressure recovery coefficients are also obtained since the physical throat areas, compression angles, and the corresponding contraction ratios can be adjusted by a large margin through very limited rotations. The variable geometry scheme is not only feasible for practical realizations, but is also simple to arrange the dynamic sealing issues in a low-temperature environment in the RBCC engine.

中文翻译：

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双风管可变几何形状 RBCC 入口的设计和数值研究

摘要 概念性地提出了一种应用广泛、几何形状可变的二维火箭联合循环（RBCC）进气道，其特点是双导管设计。入口在低马赫范围（0~4）时作为双通道状态运行，在随后的高马赫范围（4~7）过渡到单流路状态。它通过8.0度的斜坡旋转和4.0度的整流罩旋转以4马赫完成运行状态转换。 通过对典型飞行马赫数的数值模拟，观察到的起始马赫数为2.2，为平稳喷射提供了足够的运行窗口- 到冲压式喷气发动机模式转换。RBCC 入口在整个宽飞行范围内实现了全面的高质量捕获系数，尤其是在低速状态下。由于物理喉道面积、压缩角和相应的收缩比可以通过非常有限的旋转进行很大的调整，因此还可以获得满足不同模式下各种燃烧要求的合适马赫数以及较高的总压力恢复系数。可变几何方案不仅对于实际实现是可行的，而且在RBCC发动机的低温环境中布置动态密封问题也很简单。