Using ground-based cameras, researchers at NASA’s Armstrong Flight Research Center, Edwards, California, are now looking to the heavens for backgrounds upon which to capture images of supersonic shock waves.
Above: This schlieren image of shock waves created by a T-38C in supersonic flight was captured using the sun’s edge as a light source and then processed using NASA-developed code. Image Credit: NASA
Top image: This schlieren image of a T-38C was captured using the patent-pending BOSCO technique and then processed with NASA-developed code to reveal shock wave structures. Image Credit: NASA
A bright light source and/or speckled background – such as the sun or moon – is necessary for visualizing aerodynamic flow phenomena generated by aircraft or other objects passing between the observer’s camera and the backdrop.
This patent-pending method, made possible by improved image processing technology, is called Background-Oriented Schlieren using Celestial Objects, or BOSCO. This schlieren image of a T-38C was captured using the patent-pending BOSCO technique and then processed with NASA-developed code to reveal shock wave structures.
Researchers at Armstrong and NASA’s Ames Research Center at Moffett Field, California, have developed new schlieren techniques based on modern image processing methods. Shock waves, represented by distortions of the background pattern in a series of images, are accentuated using special mathematical equations. This method requires only simple optics and a featured background, that is one with a speckled appearance such as the cratered lunar surface or the mottled appearance of the sun when viewed through certain filters.
This schlieren image dramatically displays the shock wave of a supersonic jet flying over the Mojave Desert. Researchers used NASA-developed image processing software to remove the desert background, then combined and averaged multiple frames to produce a clear picture of the shock waves. Credits: NASA Photo