A scramjet inlet provides shock compression to provide high-pressure air to the combustor for burning fuel and generating thrust. Shock boundary-layer interaction (SBLI) at the surface of the inlet can result in flow separation at the inlet wall yielding undesirable effects including inlet buzz and unstart. This work presents an adaptive feedback control technique, predictive cost adaptive control (PCAC), coupled with computational fluid dynamics (CFD) to limit the adverse effects of SBLI with flow control methods. A coupling code between PCAC and CFD was developed to provide a closed-loop code between the control and CFD code (CFD-C). A Mach 2.5 inlet has been utilized for demonstration and boundary-layer bleed has been utilized as the actuation mechanism for reducing the flow separation due to SBLI. PCAC learned the relevant system dynamics using the computed wall pressure data provided to PCAC at regular time intervals during the real-time closed-loop operation eliminating the need for any prior modeling of the system. Bleed mass flow rate was calculated by PCAC and provided to CFD via the CFD-C code. Since the control algorithm presented in this work does not require calibration and prior modeling of the system, it can be impactful under varying operating conditions. This capability has been demonstrated while the inlet is operated under different angles of attack: 0°, 10°, and 15°. The results have demonstrated that the recirculation zone generated due to separation of the boundary-layer in each case was reduced once closed-loop adaptive feedback control with PCAC was applied.
Schaaf et al. (Fri,) studied this question.