This study investigates the off-design characteristics of a scoop-type streamline-tracing inlet, focusing on identifying its operable envelope using numerical and experimental methods, with experiments primarily conducted for validation purposes. The fixed geometry of streamline-tracing inlets necessitates this research, and a scoop-type inlet is targeted because it has the minimum viscous drag owing to the minimum wetted area between the streamline-tracing inlet variants. A scoop inlet with a cruise Mach number () of 6 and contraction ratio of 4.14 was designed, with three different values of and various angles of attack (AoAs) used to simulate its flight in on- and off-design freestream conditions. Computational results were used to delineate the unstart boundaries with regard to AoA for each tested . Predictably, the inlet exhibited the widest operable range for the on-design . The flow fields for the on- and off-design conditions were compared, as were the contraction ratio, captured mass flow rate, pressure ratio, inlet exit, M, and total pressure recovery. The results indicated that the inlet performance deteriorated when the flow condition deviated from the on-design condition. However, the scoop-type inlet maintained its performance for a relatively wide range of off-design conditions, confirming its potential versatility for various flight missions.

中文翻译：

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勺型流线追踪​​超燃冲压发动机入口的非设计特性

本研究研究了勺型流线追踪​​入口的非设计特性，重点是使用数值和实验方法确定其可操作包络线，实验主要用于验证目的。流线追踪入口的固定几何形状使得这项研究成为必要，并且勺型入口是目标，因为由于流线追踪入口变体之间的润湿面积最小，它具有最小的粘性阻力。设计了巡航马赫数 () 为 6、收缩比为 4.14 的勺形入口，并使用三种不同的迎角 (AoA) 值和不同的迎角 (AoA) 来模拟其在设计内和设计外自由流条件下的飞行。计算结果用于描绘每个测试的 AoA 的未启动边界。可以预见的是，入口展示了设计时最宽的可操作范围。比较了开启和关闭设计条件下的流场，以及收缩比、捕获质量流量、压力比、入口出口、M 和总压恢复。结果表明，当流动条件偏离设计条件时，入口性能恶化。然而，勺式进气道在相对较宽的非设计条件下保持了其性能，证实了其在各种飞行任务中的潜在多功能性。