Reconstructing Hypersonic Flow Over a Bluff Body from Experimental Background-Oriented Schlieren Data

Joseph P. Molnar, Elijah J. Lalonde, Christopher S. Combs, Samuel J. Grauer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations

Abstract

Background oriented schlieren (BOS) is a non-intrusive flow visualization technique that is used to characterize density in complex, high-speed flows. Hypersonic flows over bluff bodies are increasingly relevant to the design of next-generation air- and spacecraft, and BOS may help to study these devices. BOS measurements indicate 2D density gradients in the working fluid, which can be leveraged to render shock structures, quantify density ratios, and even reconstruct latent fields like velocity and pressure. High-speed tests require a fast camera exposure to freeze the flow, but increasing the shutter speed limits the signal strength, resulting in a low signal-to-noise ratio (SNR). Opening the aperture allows more light onto the sensor, increasing the SNR, but it also limits the camera’s depth of field and leads to blurry deflections. To address this, we develop an accurate forward model of BOS imaging that accounts for depth-of-field effects. We employ this model to reconstruct the density field of a hypersonic flow over a spherical bluff body. The flow is well characterized in the literature and thus provides a suitable benchmark for our algorithm. Reconstructions are performed using the neural-implicit reconstruction technique, and we also report “physics-informed” estimates based on the compressible Euler equations. Our aperture sampling approach dramatically improves the accuracy of reconstructions: the sharp shock interface is well-resolved in all our tests, irrespective of the camera’s aperture setting.

Original languageEnglish (US)
Title of host publicationAIAA SciTech Forum and Exposition, 2024
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624107115
DOIs
StatePublished - 2024
EventAIAA SciTech Forum and Exposition, 2024 - Orlando, United States
Duration: Jan 8 2024Jan 12 2024

Publication series

NameAIAA SciTech Forum and Exposition, 2024

Conference

ConferenceAIAA SciTech Forum and Exposition, 2024
Country/TerritoryUnited States
CityOrlando
Period1/8/241/12/24

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering

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