Tunnel 9 combines cutting-edge capabilities for Orion Published Jan. 30, 2007 AEDC Public Affairs ARNOLD AIR FORCE BASE, Tenn. -- A team at AEDC's Hypervelocity Wind Tunnel 9 made use of conventional and advanced measurement techniques during the aerothermal testing of NASA's scale model of the new Orion crew exploration vehicle command module. Orion is a key component being developed by NASA to support the Vision for Space Exploration. The primary objective of the Orion testing at Tunnel 9 was to obtain heating data over the model's surface covering the full operational range of the facility 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 (CFD) modeling techniques. The experimental data will be used to validate the CFD models for NASA's Orion database development. "Tunnel 9'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, project group team leader at Tunnel 9. Another team at Tunnel 9 supported the CEV test by pushing the use of Temperature Sensitive Paint (TSP) to its limits during the project's final phase. Their 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, which is similar to Pressure Sensitive Paint, is a system that includes a special paint, an ultra-violet illumination source and a sensitive charge coupled device (CCD) 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. "The traditional way of collecting heat transfer data is by use of discrete sensors," said Joe Norris, Aerospace Testing Alliance's TSP developmental lead at Tunnel 9. "You place them at various locations on the test article and collect data at a single point in certain areas. The problem with this method is that it's difficult to instrument areas like the leading edges of models, fins, and controls surfaces or we frequently do not have prior knowledge of where gages should be placed. "Furthermore, the discrete sensors are expensive and require a lot of work to install and wire electrically, sometimes taking over a month to prepare a heavily instrumented 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. It's effectively like acquiring data from tens of thousands of thermocouples." Mr. Norris said the team at Tunnel 9 had to deal with some technical challenges not experienced at other facilities working with TSP and PSP. "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 CCD cameras to take images at frame rates fast enough to calculate heat transfer." Orion is scheduled to make a first manned mission no later than 2014 as the follow-on to the space shuttle, due to be retired in 2010. College interns help in mastering global heat transfer imaging technology Tunnel 9's success with the final phase of the CEV test also benefited from a collaborative effort provided by some local college interns and a specialized industry expert. The team working on the TSP portion of the test included Dr. Marvine Hamner, the founder of LeaTech, LLC, a leading research and development engineering group specializing in fluid dynamics and polymer chemistry. "Dr. Hamner and LeaTech Technologies are the ones who developed the paints and have supported the development work from the ground up," Mr. Norris said. "We've also recruited some college students to help with the effort." He said this group included, among others, two undergraduates from the University of Maryland which is located only three miles from Tunnel 9. "Dan Getsinger, a senior in aerospace engineering, and Dave Gers, a junior in aerospace engineering, worked on the hardware for mounting lights and cameras to the test cell as part of a summer internship program," he said. "They also helped provide some of the inputs for the data reduction techniques employed in this test." Tunnel 9 co-op engineering student from the University of Cincinnati, Josh Bourquin, also assisted in setting up the equipment for the test. "We were also pleased to have Inna Kurits, a University of Maryland graduate student working on her master's degree in aerospace engineering, on our team," Mr. Norris said. "She will use the temperature data collected during CEV and develop the mathematical models to reduce the temperature data to heat transfer (data). She also worked to help set up and acquire the data." She felt fortunate to have been a part of the test, Ms Kurits said. "It is a very interesting project - I like that it had a little bit of everything," she said. "It wasn't just writing a big (computer) code, there was some hands-on stuff - theoretical modeling and some programming. So, it has been a good experience all around." Mr. Norris also acknowledged technical support and valuable information exchanges from several AEDC employees at Arnold AFB, including Marvin Sellers who has been leading the use of PSP technology at Arnold. "Marvin has been very helpful regarding our development efforts here, while our systems are inherently different due to the different facilities we operate in; Tunnel 9 has been able to leverage some of the equipment and expertise developed by the folks at the center to assist our efforts. The NASA test customer hopes that a successful demonstration of the TSP system in Tunnel 9 will help.