AirBOS-SR: Visualizing Supersonic Shock Waves with Advanced Imaging Techniques

aerospace
AirBOS-SR: Visualizing Supersonic Shock Waves with Advanced Imaging Techniques (DRC-TOPS-28)
Subsonic uses include understanding flow phenomena of engine plumes and wing tip vortices
Overview
Researchers at NASA's Armstrong Flight Research Center and Ames Research Center have developed an innovative approach for capturing images of shock waves emanating from aircraft in supersonic flight. The Air-to-Air Background Oriented Schlieren with Simultaneous Referencing (AirBOS-SR) approach offers a significant upgrade over previous schlieren techniques because it enables multiple frames of close-up images from various angles, including a side-view perspective. NASA will use this schlieren technology to confirm the design of the agency's X-59 Quiet Supersonic Technology (X-59 QueSST) aircraft, anticipated to produce a soft thump in place of a disruptive sonic boom. In addition to many supersonic uses, the new technique also has potential uses for visualizing air density gradients of wing tip vortices, engine plumes, and rotorcraft.

The Technology
Supersonic flight over land is currently severely restricted because sonic booms created by shock waves disturb people on the ground and can damage property. Schlieren imaging techniques capture shock wave images by visualizing air-density gradients caused by aerodynamic flow. Researchers are using these images to study shock waves as part of the effort to make sonic booms quieter and to open the possibility of overland supersonic flight. How It Works It has been a decade in the making to adapt what was originally a wind tunnel-based method into a proven flight test technique. The AirBOS-SR method uses schlieren imaging with a novel way to collect reference and data images to secure measurable shock waves. With AirBOS-SR, two aircraft fly in formationa target aircraft and a camera-equipped aircraft that takes both reference and data images of the target aircraft. The camera-equipped aircraft continuously takes reference frames that are automatically paired with individual data frames. As a result, AirBOS-SR allows for different viewing angles and multiple flight conditions, such as acceleration and aircraft configuration changes. Why It Is Better Previous schlieren techniques* have used the ground or a celestial object, such as the sun, as a background reference point. These techniques work by comparing a set of reference frames taken before a target aircraft enters a field of view with a set of data frames collected after the aircraft enters the field. To evaluate the X-59 QueSST aircraft, NASA needs to see multiple frames of close-up images from a side-view perspective. AirBOS-SR will meet this need. Furthermore, AirBOS-SR benefits applications well beyond NASA's supersonic needs. In subsonic applicationsincluding airfoils, helicopters and other rotorcraft, and non-aircraft applications such as wind turbinesAirBOS-SR helps designers better understand vortex location development to improve performance, reduce noise, and understand relative positioning for increased efficiency. *Air-to-Air Background-Oriented Schlieren (AirBOS) and Background-Oriented Schlieren Celestial Object (BOSCO)
Benefits
  • Flexible: Allows for real-time adjustments and data collection at different perspective angles
  • Efficient: Enables visualizations of dynamic conditions, such as accelerations, decelerations, and store separations
  • Improved data: Collects large sample sets of data and reference images, resulting in a higher signal-to-noise ratio and improved images

Applications
  • Studying shock waves for: Supersonic aircraftSubsonic aircraft
  • Understanding flow phenomena and air density changes for:Wing tip vorticesEngine plumesWind turbinesRotorcraft
Technology Details

aerospace
DRC-TOPS-28
DRC-018-014

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