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Arnold teams provide NASA with test data

  • Published
  • By Philip Lorenz III
  • Arnold Engineering Development Center
Two teams at the Engineering Development Center's Hypervelocity Wind Tunnel 9 here were recently involved in tests for NASA's next crew exploration vehicle.

One team made use of conventional and advanced measurement techniques during the NASA-sponsored aerothermal testing on a scale model of the space agency's new Orion, the projected spacecraft that will send a new generation of explorers to the moon.

Orion is part of the Constellation Program to send human explorers to other destinations in the solar system. Orion is scheduled to make a manned mission no later than 2014 as the follow-on to the space shuttle, due to be retired in 2010.

The test objective was to obtain heating data over the model's surface at Mach 8 and 10 freestream conditions.

Unlike the development of the Apollo capsule, where the database was populated entirely using experimental data, the Orion database is being developed using advanced computational fluid dynamic techniques. The experimental data will be used to validate the computational fluid dynamic models for NASA's Orion database development.

The facility's unique high Mach number and high pressure capabilities allowed NASA to obtain data on the vehicle, "which they were not able to obtain in any other facility," said Joe Coblish, the project group team leader at Tunnel 9.

A second Tunnel 9 team provided support by pushing the use of temperature sensitive paint, or TSP, to its limits during the project's final phase. The goal was to further develop and demonstrate TSP's effectiveness and viability to collect test data in Tunnel 9's unique high-temperature and high-pressure hypersonic environment.

TSP is a system that includes a special paint, an ultra-violet illumination source and a sensitive-charge coupled-device camera to obtain surface temperature data. The paint is applied to the model in two layers -- a white undercoat and the TSP layer. The white undercoat provides a uniform reflective surface for the TSP. The illumination source excites the TSP layer, which fluoresces a bright red color with its intensity inversely proportional to the surface temperature on the model.

"TSP allows us to use what is described as a global mapping technique to get the desired parameter -- heat transfer in this case -- from the entire surface of the test article," said Joe Norris, Aerospace Testing Alliance's TSP developmental lead at Tunnel 9. "It's effectively like acquiring data from tens of thousands of thermocouples."

The team at Tunnel 9 had to deal with some technical challenges not experienced at other facilities working with TSP and Pressure Sensitive Paint, Mr. Norris said.

"Tunnel 9's unique combination of relatively short run times and high heating rates presents challenges that are unique in the world of TSP/PSP," he said. "High-quality, high-output, stable illumination fields are needed to combine with high-end, scientific-grade cameras to take images at frame rates fast enough to calculate heat transfer."

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