NASA advances pressure-sensitive paint research capabilities

Many of us have used paint by number sets to create beautiful color photos.

For years, NASA engineers studying aircraft and rocket design in wind tunnels have used computers to generate images from “paint by paint” – pressure sensitive paint (PSP), turning that childhood entertainment overturned.

Advances in the use of high-speed cameras, supercomputers, and even more sensitive PSPs now make this per-paint process 10,000 times faster, creating engineering visuals at 1,000 times higher resolution.

So, what is the big difference between the “old” ability used by NASA and the “new” ability and “new” for over a decade?

“We’re looking forward to seeing you get the chance to get the most out of your business,” said E. Lara Lash, aerospace engineer at NASA’s Ames Research Center in Silicon Valley, California.

Using PSP, NASA researchers are studying the massive effects of relatively smooth air flowing through aircraft wings and bodies. With UPSP you can see in detail what happens when more turbulent air is present.

In some cases, if there is a new feature, researchers can get the wind tunnel data they are looking for within 20 minutes. It’s fast enough to allow engineers to adjust their tests in real time.

Typically, researchers record wind tunnel data and then return it to the lab for deciphering it days or weeks later. If they find themselves need more data, it can take another few weeks or months to wait side by side for another turn in the wind tunnel.

“The results of these improvements provide a data product that is immediately useful to aerodynamic engineers, structural engineers, or engineers in other fields,” Rush said.

Robert Pearce, NASA assistant administrator at Aeronautics, recently saw a demonstration of data generated by the UPSP published in Ames, and welcomed the new tool as a national asset available to researchers across the country.

“It’s a unique NASA innovation that’s not available anywhere else,” Pierce said. “This will help maintain NASA’s global leadership in wind tunnel capabilities.”

How it works

Unique paint is applied to scale models of aircraft or rockets mounted in wind tunnels with specific types of lights and cameras using both PSP and UPSP.

When illuminated during testing, the paint color brightness changes depending on the level of pressure experienced by the model as the air lash flow. Darker shades mean higher pressure. Bright colours mean low pressure.

The camera captures the intensity of the brightness, and the supercomputer turns that information into a set of numbers representing the pressure value. This makes it available to engineers to research and gather truths that can be made about the structural integrity of vehicle design.

“Aerodynamic power can cause different parts of the vehicle to vibrate to varying degrees,” Rush said. “Vibrations can damage what the vehicle is carrying, or even tear itself apart. Data going through this process helps prevent that.”

Traditionally, pressure measurements are taken using sensors connected to small plastic tubes stretched inside the model, plunging through small holes at important locations along the surface of the wings and fuselage.

Each point provides a single pressure reading. Engineers must use mathematical models to estimate the pressure values ​​between individual sensors.

In PSP, there is no need to estimate numbers. The paint covers the entire model, so its brightness reveals pressure values ​​across the surface, as seen in the camera.

Make it better

The implementation, testing and availability of UPSPs was the result of the success of five years of efforts launched in 2019, with researchers taking on the challenge of significantly improving the capabilities of PSPs with related cameras and computers.

The NASA team’s desire is to develop and demonstrate a better process of obtaining, processing and visualizing data using well-equipped wind tunnels and supercomputers, making the tool available to NASA wind tunnels nationwide.

The focus on the capacity challenges was in an 11-foot transnic wind tunnel at NASA’s Unitary Plan facility. The team connected to a nearby NASA Advanced Supercomputing facility, both located in Ames.

Inside the wind tunnel, a scale model of NASA’s space launch system rocket served as the primary subject during the challenge.

As the agency has completed Artemis, I have completed the irregular moon flight test mission, so researchers can match the flight-recorded data with wind tunnel data to see a comparison of reality and predictions.

With the official completion of the Capability Challenge at the end of 2024, the UPSP team plans to deploy it to other Wind tunnels and engage potential users with interest in aviation or spaceflight.

“This is the NASA capabilities we can provide to industry, academia and other government agencies to use and investigate these new tools,” Rush said.