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LUMISTAR INFRARED IMAGING NEWS

By Lumistar's Chief Scientist

June 15, 2014

Infrared Camera Helps Analyze Parts At Over Mach 5

Lumistar Corp Mach 5

Manchester University (Manchester, UK) researchers are using a thermal imaging camera to examine the performance of aerospace components in a wind tunnel. The knowledge gained by the wind tunnel tests will help designers of high-speed aircraft and re-entry space vessels that need to bring payloads to orbit and return to Earth.  The wind tunnel at the university is one of the few experimental facilities in Europe that can reach Mach numbers higher than 5. According to Professor Konstantinos Kontis, head of the Aerospace Research Group at Manchester University , the prolonged exposure to friction induced heat caused by the air flowing across the surface of an aircraft traveling at Mach 5 can be detrimental to the structural integrity of the material used in aircraft components. It is therefore important to test such components extensively before they are deployed in the field.

To capture thermal maps of the entire surface of the parts under test in the wind tunnel, the thermal imaging camera which contains an uncooled microbolometer detector that produces thermal images at a thermal sensitivity of 50mK (0.05°C), is located on top of the test chamber, looking in through a protective housing. This allows the camera to accurately map the thermal hot spots caused by the air friction, without being subjected to the force of high velocity air-flows. The full resolution can be captured at a frame rate of 50 fps, but it also provides high-speed windowing modes that allow the operator to increase the frame rate to 200 fps. The captured thermal footage along with it’s radiometric temperature data is analyzed with specialized software. “We use it to capture the data, define special regions of interest and export the temperature measurement strings to third party software for an in-depth analysis of the data,” says Dr. Erdem. On one end of the wind tunnel there is a chamber capable of containing pressurized air up to 15 bar, 15 times Earth’s regular atmospheric air pressure. At the other end is a vacuum tank which is brought to 1 milibar, one thousandth of regular atmospheric air pressure. In between the two is the test chamber where the test object is placed. As the pressurized air travels from the pressure chamber into the vacuum chamber, it passes the test object with a speed of about 6,000 kilometer per hour, similar to traveling at Mach 6 or approximately four thousand miles per hour at 50,000 feet (flight level 50), the highest altitude at which planes don’t lose air density. Velocity at sea level to obtain Mach 6 is 3,147 miles per hour. The difference in the velocity at different altitudes is due to the fact that the earth is spherical, so the amount of speed needed to cover a certain distance of the earth’s surface at a low altitude, is a lot lower than the amount needed to cover the same distance of the earth’s surface at a very high altitude.