针对涡轮基组合循环（TBCC）发动机由冲压动力向涡轮动力转换过程中进气道内非定常流动特征展开研究，通过试验与数值仿真（CFD）相结合的方法分析了进气道整体波系变化过程以及沿程不同位置的压力变化规律，获得了进气道模态切换过程中低速通道再起动过程动态特性以及分流板转速对这一过程的影响。结果表明：考虑涡轮动力起动影响，进气道低速通道逐渐开启过程中低速通道会经历6个典型阶段：阶段1，分流板开启，边界层气流进入通道，通道压力小幅下降；阶段2，超声速主流进入通道，通道压力大幅上升；阶段3，通道内流量积聚压力上升，激波串前传，随后越过放气腔，泄流压力下降，激波后移；阶段4，低速通道分离包不断膨胀与收缩，引起激波振荡；阶段5，分离包吐出通道，发生喘振；阶段6，下游节流度（TR）减小，喘振结束，低速通道恢复起动。在低速通道再起动过程中，分流板的转速会影响流道内压力振荡频率以及幅值，并且分流板转速越小，压力振荡频率越低、幅值越大。此外，低速通道再起动过程中，分流板转速也会影响喘振发生的时机，分流板转速越小，越易引发进气道低速通道喘振。所得结果可为组合动力发动机平稳模态转换提供理论支持。

This paper investigates the unsteady flow characteristics within the inlet during the ram-to-turbo transition of a Turbine-Based Combined Cycle （TBCC） engine. Through a combined approach of wind tunnel test and Computational Fluid Dynamics （CFD） simulations， it analyzes the evolution of the inlet shock system and the static pressure variation patterns along critical flow path locations， and acquires the dynamic restart characteristics of the low-speed duct during inlet mode transition and the influence of flow splitter rotational speed on this process. The results indicate that during the progressive opening of the low-speed duct under turbine-mode startup conditions， six distinct phases occur： in phase 1， flow splitter deployment initiates boundary layer ingestion into the duct， causing minor static pressure drop； in phase 2， supersonic core flow enters the duct， triggering significant static pressure rise； in phase 3， flow accumulation induces pressure buildup and shock train forward propagation， followed by shock traversal past the bleed cavity， with subsequent cavity depressurization causing shock recession； in phase 4， cyclic expansion/contraction of the low-speed duct separation bubble induces shock oscillation； in phase 5， shock expulsion along the separation bubble triggers inlet buzz； in phase 6， reduction in downstream Throttling Ratio （TR） terminates buzz， enabling low-speed duct restart. During the low-speed duct restart process， the rotational speed of the flow splitter vanes influences both the frequency and amplitude of pressure oscillations within the flow path， with lower rotational speeds resulting in reduced oscillation frequencies and increased amplitudes. Moreover， during low-speed duct restart， the rotational speed also affects the onset timing of buzz， where lower speeds more readily trigger inlet buzz in the low-speed duct. This study provides a theoretical foundation for achieving smooth mode transition in combined-cycle engines.