Schlieren System Captures Brilliant Shockwave Images
Schlieren System Captures Brilliant Shockwave Images (DRC-TOPS-40)
High-speed imaging technology offers applications for aerospace, construction, and renewable energy
Innovators at NASA's Armstrong Flight Research Center have developed a novel system for capturing images of shockwaves created by supersonic aircraft. The Background Oriented Schlieren Using Celestial Objects (BOSCO) technology uses a celestial object, such as the sun, as a background to secure unique, measurable shockwave images of full-scale aircraft. The patented image-processing technology captures hundreds of observations with each shockwave, benefitting NASA engineers in their efforts to develop a supersonic aircraft that will produce a soft "thump" in place of a disruptive sonic boom. In addition to many aerospace uses, the technology has potential uses for visualizing air density gradients in the construction and renewable energy industries.
Supersonic flight over land is generally prohibited because sonic booms created by shockwaves disturb people on the ground and can damage property. Armstrong innovators are working to solve this problem through a variety of innovative techniques that measure, characterize, and mitigate sonic booms. The BOSCO technology is helping researchers understand how sonic booms travel through the air. How It Works Armstrong's patented system visualizes air density gradients generated by air compressing as it flows around an object. Researchers first obtain a celestial background image and then collect a series of images of an object in supersonic flow in front of the celestial object. The density change in the air refracts the light, shifting the background as compared to the undisturbed background image. The amount of movement corresponds directly to density gradients in the airflow. Using computer algorithms to analyze the images, resultant images essentially show the distortions caused by the aerodynamic flow of shockwaves passing between the camera and the celestial background. Why It Is Better Schlieren photography has been used for years in wind tunnels, where the environment is controlled. BOSCO enables its use in the real atmosphere with real propulsion systems. Studying life-sized aircraft flying through Earth's atmosphere provides better results than modeling and can help engineers design better and quieter supersonic airplanes. In addition to studying shock waves for aircraft, NASA's schlieren techniques have the potential to aid the understanding of a variety of flow phenomena and air density changes, such as investigating air flows around tall buildings and the tips of wind turbines and helicopter blades.
- Flexible: Enables schlieren-type imaging on large outdoor objects without the need for complicated equipment or setup
- Location independent: Uses a celestial object as a reference background, enabling ground- or aircraft-based use
- Full scale: Observes aerodynamics in actual operating environment
- Innovative: Enables airflow visualization, as it detects very small shifts (differences) between the celestial object background image and the object image
- Efficient: Uses optical filters to increase the effectiveness of reference backgrounds
- Economical: Works with commercial off-the-shelf (COTS) hardware
- AircraftVisualization of supersonic and subsonic plumes Study of shockwaves and vorticesStudy of flows caused by heating
- Wind Turbines
- Large structures Study of aerodynamic properties