NASA captures first images of supersonic shockwaves colliding in flighthttps://indianexpress.com/article/technology/science/nasa-captures-first-images-of-supersonic-shockwaves-colliding-in-flight-5617959/

NASA captures first images of supersonic shockwaves colliding in flight

NASA has captured groundbreaking images of shockwaves from two supersonic aircraft, as part of its efforts to develop planes that can fly faster than the speed of sound without producing thunderous sonic boom.

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Using the schlieren photography technique, NASA was able to capture the first air-to-air images of the interaction of shockwaves from two supersonic aircraft flying in formation. These two U.S. Air Force Test Pilot School T-38 aircraft are flying in formation, approximately 30 feet apart, at supersonic speeds, or faster than the speed of sound, producing shockwaves that are typically heard on the ground as a sonic boom. The images, originally monochromatic and shown here as colorized composite images, were captured during a supersonic flight series flown, in part, to better understand how shocks interact with aircraft plumes, as well as with each other. (Image: NASA)

NASA has captured groundbreaking images of shockwaves from two supersonic aircraft, as part of its efforts to develop planes that can fly faster than the speed of sound without producing thunderous sonic boom, the US space agency said.

The images were captured during the fourth phase of Air-to-Air Background Oriented Schlieren flights, or AirBOS, which took place at NASA’s Armstrong Flight Research Center in the US.

The flight series saw successful testing of an upgraded imaging system capable of capturing high-quality images of shockwaves, rapid pressure changes which are produced when an aircraft flies faster than the speed of sound, or supersonic, NASA said in a statement.

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One of the greatest challenges of the flight series was timing. In order to acquire this image, originally monochromatic and shown here as a colorized composite image, NASA flew a B-200, outfitted with an updated imaging system, at around 30,000 feet while the pair of T-38s were required to not only remain in formation, but to fly at supersonic speeds at the precise moment they were directly beneath the B-200. The images were captured as a result of all three aircraft being in the exact right place at the exact right time designated by NASA’s operations team. (Image: NASA)

“I am ecstatic about how these images turned out,” said Physical Scientist J T Heineck of NASA’s Ames Research Center. “With this upgraded system, we have, by an order of magnitude, improved both the speed and quality of our imagery from previous research,” Heineck said.

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Shockwaves produced by aircraft merge together as they travel through the atmosphere and are responsible for what is heard on the ground as a sonic boom.

The system will be used to capture data crucial to confirming the design of the agency’s X-59 Quiet SuperSonic Technology X-plane which will fly supersonic, but will produce shockwaves in such a way that, instead of a loud sonic boom, only a quiet rumble may be heard.

The ability to fly supersonic without a sonic boom may one day result in lifting current restrictions on supersonic flight over land, the US space agency said.

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When aircraft fly faster than the speed of sound, shockwaves travel away from the vehicle, and are heard on the ground as a sonic boom. NASA researchers use this imagery to study these shockwaves as part of the effort to make sonic booms quieter, which may open the future to possible supersonic flight over land. The updated camera system used in the AirBOS flight series enabled the supersonic T-38 to be photographed from much closer, approximately 2,000 feet away, resulting in a much clearer image compared to previous flight series. (Image: NASA)

The images feature a pair of T-38s from the US Air Force Test Pilot School at Edwards Air Force Base, flying in formation at supersonic speeds. The T-38s were flying approximately 30 feet away from each other, with the trailing aircraft flying about 10 feet lower than the leading T-38.

With exceptional clarity, the flow of the shock waves from both aircraft is seen in the images, and for the first time, the interaction of the shocks can be seen in flight.

“We are looking at a supersonic flow, which is why we are getting these shockwaves,” said Neal Smith, a research engineer with AerospaceComputing Inc at NASA Ames’ fluid mechanics laboratory.

“What is interesting is, if you look at the rear T-38, you see these shocks kind of interact in a curve,” he said. “This is because the trailing T-38 is flying in the wake of the leading aircraft, so the shocks are going to be shaped differently. This data is really going to help us advance our understanding of how these shocks interact,” Smith said.

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The X-59 Quiet SuperSonic Technology X-plane, or QueSST, will test its quiet supersonic technologies by flying over communities in the United States. X-59 is designed so that when flying supersonic, people on the ground will hear nothing more than a quiet sonic thump – if anything at all. The scientifically valid data gathered from these community overflights will be presented to US and international regulators, who will use the information to help them come up with rules based on noise levels that enable new commercial markets for supersonic flight over land. (Image: NASA)

The study of how shockwaves interact with each other, as well as with the exhaust plume of an aircraft, has been a topic of interest among researchers.

Previous, subscale schlieren research in Ames’ wind tunnel, revealed distortion of the shocks, leading to further efforts to expand this research to full-scale flight testing.