A mere 25 degrees can make a big difference in the operating efficiency of a turbine engine, and researchers at ORNL are helping Rolls Royce to demonstrate a technique called phosphor thermography. The technique could be used in the future to optimize turbine designs. Using special optics, a laser and phosphor powder, Steve Allison and colleagues in the Engineering Science and Technology Division can make extremely accurate measurements at temperatures up to 1,706 degrees Celsius. The ORNL method, which is patented and has received an R&D 100 Award, uses fiber optics and pulses from a small ultraviolet laser to excite the phosphor. Light detectors measure the time it takes the fluorescence to decay, giving researchers an extremely accurate measure of temperature. The technique promises to be more reliable and accurate than conventional methods using wires and thermocouples or pyrometers (cameras). In the project with Rolls Royce, ORNL is assisting with the Advanced Military Demonstration Engine for the U.S. Air Force.
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