@article{sharma_narayanaswamy_2026, title={Shock Train Control in High Speed Inlets and Isolators}, volume={1}, DOI={10.2514/6.2026-2561}, abstractNote={Shock trains in supersonic inlet–isolator systems generate the pressure rise required for scramjet combustion but are highly sensitive to back-pressure disturbances that can drive upstream shock migration and unstart. Preventing such instability demands control strategies that operate on millisecond timescales comparable to the underlying flow dynamics. This work integrates detailed flow diagnostics with embedded-hardware development to establish the feasibility of real-time, microcontroller-based shock-train stabilization. A Teensy 4.1 microcon- troller is combined with high-speed analog pressure sensors and proportional solenoid valves to form a compact feedback architecture. Bench-top latency measurements using single- and dual-solenoid configurations demonstrate that the end-to-end electronic and electropneumatic latency is compatible with the low-frequency breathing modes of the shock train. Experiments employ high-speed schlieren imaging and surface oil-flow streakline visualization to resolve both the instantaneous shock dynamics and the mean separation topology within the isolator. The shock train was tracked in both started and unstarted regimes, revealing its coherent behavior under stable operation and its progressive breakdown when subjected to controlled disturbances. Unstart was induced using a transverse jet mounted 2 mm downstream that calibrated back-pressure rise at the isolator exit. Complementary oil-flow streaklines document the progressive growth of the separation bubble, from weak downstream vortices to a large upstream-migrating recirculation region. The measurements demonstrate that compact embed- ded controllers can directly engage the low- and mid-frequency instability modes that drive shock-train collapse and unstart. High-resolution schlieren tracking and oil-flow visualizations define the underlying flow-physics pathways governing these instabilities and provide the basis for proportional, spatially adaptive actuation strategies. The combined diagnostic evidence and latency characterization confirm that such controllers possess sufficient bandwidth and authority to interact with the dominant unsteady mechanisms, establishing a validated foundation for real-time unstart-mitigation in hypersonic inlet architectures.}, author={Sharma, Lavya and Narayanaswamy, Venkateswaran}, year={2026}, month={Jan} }