Air-to-air background oriented schlieren technique

Patent · Tue Jan 01 04:00:00 EST 2019

OSTI ID:1531399

Heineck, James Thomas; Banks, Daniel William; Schairer, Edward Treanor; Bean, Paul Stewart; Haering, Jr., Edward Andrew; Pauer, Brett Arnold; Martin, Brittany Joan; Larson, David Nils

An air-to-air background-oriented Schlieren system and method for measuring and rendering visible density changes in air that cause a refractive index change by an airborne vehicle. A sensor aircraft equipped with a high-speed visible spectrum camera travels at low airspeed on a predetermined route and on a level altitude over a background having consistent contrast and sunlight reflectivity. The target aircraft, traveling on the same predetermined route but at an altitude between the sensor aircraft and the ground (background) passes beneath the sensor aircraft. The camera on the sensor aircraft captures a series of images including a reference image immediately before the target aircraft enters the image frame followed by several data images as the target aircraft passes through the image frame. The data images are processed to calculate density gradients around the target aircraft. These density gradients include shockwaves, vortices, engine exhaust, and wakes. Air density gradients cause a refractive index change in the fluid and a slight distortion in the background pattern of the data image. Image processing that compares the data image to the reference image yields the difference caused by the density gradient.

• Research Organization: National Aeronautic and Space Administration (NASA), Washington, DC (United States)
• Sponsoring Organization: USDOE
• Assignee: The United States of America as represented by the Administrator of NASA (Washington, DC)
• Patent Number(s): 10,169,847
• Application Number: 15/229,555
• OSTI ID: 1531399
• Country of Publication: United States
• Language: English