@article{schram_narayanaswamy_2026, title={Experimental Investigation of Hypersonic Performance Inlet at Sub-Design Mach Number with Varying Angle of Attack}, volume={1}, DOI={10.2514/6.2026-1974}, abstractNote={The response of an underspeed, stream-traced hypersonic performance inlet undergoing an angle-of-attack sweep from -7.93 to 8.6 degrees is investigated. Fast-response pressure-sensitive paint is used to obtain temporally resolved surface pressure fields and associated shock structures, complemented by high-speed schlieren imaging of the external flow features. As the angle of attack increases, the inlet transitions from a started to an unstarted operating mode at 7.4 degrees, and remains unstarted until alpha is reduced to 6.3 degrees, demonstrating clear hysteresis in the unstart/restart process. The combined measurements highlight the capability of surface pressure-field imaging to capture distinct shock motions and unstart signatures during off-design pitch maneuvers.}, author={Schram, Matthew J. and Narayanaswamy, Venkateswaran}, year={2026}, month={Jan} }
 @article{schram_stramecky_narayanaswamy_2025, title={Unstart Sensitivity of Hypersonic Streamtraced Inlets During Angle-of-Attack Operation}, volume={5}, DOI={10.2514/1.J064532}, abstractNote={The propensity of a streamtraced hypersonic Busemann or “sugar scoop” inlet to unstart is experimentally and computationally investigated at positive and negative angles of attack. The backpressure was applied at the isolator exit in the form of an aerodynamic blockage from a high-momentum jet to trigger inlet unstart. High-speed schlieren photography revealed two distinguishable responses during backpressured operation at different angles of attack. At low backpressures, a “weak response” was observed where pseudoshocks were disgorged from the inlet’s internal contraction passage but with a supersonic flow channel present at the cowl closure. When the backpressure was increased, a “strong response” was observed where the entirety of the flow entering the internal contraction segment of the inlet was subsonic, which evidenced the completion of the unstart process. The weak response was observed at a lower backpressure setting with increasing angles of attack. However, a smaller subsequent increase in backpressure was required to achieve the strong response at lower angles of attack compared to higher angles of attack. Computational simulations anchored on the schlieren imagery and two-dimensional pressure fields, measured in the inlet external contraction region, were performed to probe the disparity in the unstart response across different angles of attack. The differences in operational limits and sensitivity margins were attributed to the viscous effects and momentum fluxes through the inlet/isolator.}, journal={AIAA Journal}, author={Schram, Matt and Stramecky, William and Narayanaswamy, Venkat}, year={2025}, month={Jun} }