February 28, 2014
NASA Heads To Australia To Tap High-Altitude Ice
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April Flowers for redOrbit.com - Your Universe Online
Another concern year round, however, is ice formation inside the engine while the plane is in flight. An international research group, including NASA scientists, will begin studying the problem during the summer months in Darwin, Australia. The team is using a specially equipped French jet to analyze high altitude ice crystals in an effort to improve aviation safety.
The European Airbus-led High Altitude Ice Crystals (HAIC)/High Ice Water Content (HIWC) flight campaign is being supported by engineers and scientists from three NASA facilities through March 2014. The primary scientific goal of the HAIC/HIWC campaign is to fly the French jet into weather that produces specific icing conditions in order to study the characteristics present.
An isokinetic probe is being supplied by NASA's Glenn Research Center for the Darwin flights. The probe was designed and built by Science Engineering Associates and National Research Council Canada, with funding from NASA and the Federal Aviation Administration. NASA Glenn is also supplying instrument and meteorological ground support. Mounted under the wing of a French Falcon 20 aircraft, the probe measures the total water content in clouds that have high concentrations of ice crystals in the vicinity of oceanic and continental thunderstorms.
NASA Glenn has been doing icing research for 7 decades. "The data captured during the HAIC/HIWC campaign will add to the ground-based icing research NASA has already conducted in Glenn’s Propulsion Systems Laboratory," said Tom Ratvasky, the NASA Glenn icing flight research engineer supporting the campaign. "We have tested a full scale engine under high altitude ice crystal icing conditions in that lab."
The research is also being supported by NASA's Langley Research Center and NASA's Goddard Institute for Space Studies. Scientists at Langley are contributing sensors expertise, with one team analyzing data from the Falcon's onboard weather radar and another capturing satellite imagery to help forecast where the jet might encounter the best icing conditions. The research team at Goddard is providing their cloud expertise by analyzing flight data to improve the modeling algorithms used to predict the high ice concentrations in these environments.
"The aviation industry around the world is very interested in this research. That's because ice crystals at high altitudes are not normally detected by onboard weather radar and visibly do not appear to be a danger to pilots,” said Steve Harrah, HAIC/HIWC weather radar principal investigator at NASA Langley.
"If those crystals are ingested into a turbofan engine and reach its core, they can cause a temporary loss of power – with no warning," added Ratvasky.
More than 200 incidents where turbofan jet engines have lost power during high-altitude flights have been recorded over the last 20 years. The aircraft in many of these events were flying in the vicinity of heavy storm clouds. Their weather radars, however, showed little activity at their flight altitude. A theory that the planes are flying through clouds with high concentrations of small ice crystals has been developed by the investigators.
The ice crystals in these clouds are drawn into the engines where they melt on the warm surfaces inside. During flight, these surfaces eventually become cold enough that ice begins to build up, affecting the engine's normal operation. Because more planes are flying and at higher altitudes with more efficient bypass engines, this type of ice crystal icing may be occurring more often.
"The research that will be compiled during the flight campaign will build on or redefine what we know about ice crystal icing at high altitudes," said Ratvasky. “It will also help us better understand the physical processes that cause high concentrations of crystals in certain areas."
The results of this study will provide better information to the aviation regulatory agencies around the world, as well as helping to advance the development of technologies that might someday be able to detect the presence of ice crystals, or lessen the effects of the crystals in flight.