Direct Measurements of Shock Impingement in a Busemann Inlet via a Miniature Embedded Imaging System

Eagan, Griffin D.; Lewis, Christopher J.; Alles, Ryan M.; Klingaman, Kyle C.; Davenport, Kirk; Gragston, Mark; Rice, Brian E.; Hamilton, Michael C.; Thurow, Brian S.

doi:10.2514/6.2023-2256

Cited by 5 publications

References 6 publications

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Dynamics of a 3-D inlet/isolator measured with fast pressure-sensitive paint

Bustard,

Noftz,

Hasegawa

et al. 2024

Exp Fluids

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Fast pressure-sensitive paint (PSP) was applied to an inlet/isolator designed using the Osculating Internal Waverider Inlet with Parallel Streamlines (OIWPS) method. The dorsal isolator surface pressure was measured using anodized-aluminum PSP through transparent cast acrylic that makes up the ventral portion of the isolator. Temperature-sensitive paint was utilized to correct for the PSP’s temperature sensitivity. The model was tested under Mach 5.7 flow at Re $$=$$ = 8.5 $$\times 10^6$$ × 10 6 /m and 10.2 $$\times 10^6$$ × 10 6 /m in the AFOSR–Notre Dame Large Mach-6 Quiet Tunnel (ANDLM6QT) under conventional noise conditions. Flow phenomena, such as shocks originating in the inlet and flow separation at the throat, were visualized with high spatial resolution. The dynamics measured by the PSP and pressure transducers matched well where the spectral signal-to-noise ratio was above unity. Power spectral densities showed significant frequency content at $$\approx$$ ≈ 1 kHz in the shock-wave/boundary-layer interaction (SWBLI) regions. Coherence analysis showed a linear relationship between the unsteady pressures at locations underneath different SWBLI in the isolator, with the exception of the Busemann throat shock. Temporal correlation of shock positions indicated that disturbances propagated downstream at 114% of the core-flow velocity; however, improved calculations of the core-flow velocity are needed to refine this assessment. The surface pressure fields at Re = 8.5 $$\times 10^6$$ × 10 6 /m and 10.2 $$\times 10^6$$ × 10 6 /m were quantitatively very similar, and the results in the ANDLM6QT were qualitatively similar to previous studies in the Boeing/AFOSR Mach-6 Quiet Tunnel under noisy flow.

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Dynamics of a 3-D inlet/isolator measured with fast pressure-sensitive paint

Bustard,

Noftz,

Hasegawa

et al. 2024

Exp Fluids

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Onboard background-oriented schlieren imaging using consumer-grade hardware

Quinn,

Crowther,

Wood

et al. 2024

Aeronaut. j.

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A demonstration of a fully onboard method for generating background oriented schlieren (BOS) data on a jet exhaust is presented. Readily available commercial camera equipment is used to capture in-flight imagery of a miniature jet engine exhaust mounted on a custom-built model aircraft. The setup for image acquisition and processing algorithms are described. A new process for registration of images to reduce the degrading effects of vibration and flexure of the airframe are developed and presented along with the underpinning BOS algorithm. Results show that jet flows can be visualised using this technique using a contained system on a single aircraft and demonstrate how a simple technique, such as BOS, can be democratised to such an extent that the cost of conducting in-flight jet measurements can be reduced to the budget of any model aircraft flyer.

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Event-Based Measurement of Aeroelastic Structure in High-Speed Flow

Hsu,

Tan,

Chen

et al. 2024

AIAA Journal

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In high-speed aerodynamics research, point sensors are ideal for embedding in test models but lack spatial resolution, whereas high-speed cameras offer spatiotemporally resolved measurement but involve significant footprint, cost, and data size. To address these tradeoffs, this study explores the application of nascent event-based cameras for high-speed tests. Event-based cameras support continuous, data-sparse kilohertz-equivalent imaging at [Formula: see text] resolution, on form factors as small as 36 mm and 40 grams in mass, combining the benefits of point sensors and high-speed cameras. However, these attributes come from asynchronous pixels that necessitate unique operating and postprocessing approaches. Here, the authors adapted event-based cameras for two-/three-dimensional photogrammetric tracking of aeroelastic structures, demonstrating an event-based workflow and two tracking algorithms (mean-shift filtering and circle fit). Bench-top validations achieved three-dimensional precision of 0.35 mm/s on 20 mm/s motion across a 259 mm field of view, while two-dimensional measurements of an aeroelastic titanium panel in Mach 0.76 transonic flow successfully identified millimeter-scale vibrations at 43.7, 120, and 270 Hz, validated against a laser displacement and high-speed camera. The transonic test’s raw data were 145.8 MB on the event-based camera, compared to 88.5 GB on the high-speed camera. The presented results demonstrated the viability of event-based techniques in high-speed aerodynamic testing, while highlighting challenges such as polarity switching and pixel latency.

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Direct Measurements of Shock Impingement in a Busemann Inlet via a Miniature Embedded Imaging System

Cited by 5 publications

References 6 publications

Dynamics of a 3-D inlet/isolator measured with fast pressure-sensitive paint

Dynamics of a 3-D inlet/isolator measured with fast pressure-sensitive paint

Onboard background-oriented schlieren imaging using consumer-grade hardware

Event-Based Measurement of Aeroelastic Structure in High-Speed Flow

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