Unsteady flow regimes and bleed-controlled flow splitting in a dual-flow-channel supersonic inlet

This study investigates the flow-splitting characteristics of a dual-flow-channel supersonic inlet during mode transition under turbine channel throttling. Numerical simulations are performed at three representative opening degrees to analyze both steady and unsteady flow behaviors near the limiting back pressure. The results show that flow redistribution occurs under critical conditions, accompanied by strong unsteady oscillations. The unsteady flow exhibits distinct regimes depending on the opening degree, identified using cross-correlation analysis of pressure signal pairs and spectral analysis of the resulting correlation functions, distinguishing a convection-dominated regime with a single dominant frequency and high coherence (OD3) from a multi-mechanism coupled regime with multiple frequencies and reduced coherence (OD4). By widening the bleed slot under the OD2 condition, the flow recovers a globally coherent oscillatory mode with a higher dominant frequency, while local reverse propagation emerges. This demonstrates that the relative bleed mass flow rate, rather than the absolute bleed capacity, governs the stability and dynamic behavior of the flow field. These findings highlight the critical role of bleed in regulating shock–boundary layer interaction and provide physical insight for improving flow stability and mode transition performance in dual-flow-channel inlets.