Icing on aircraft can be treacherous. When a plane flies through clouds of freezing water droplets, the moisture adheres to the aircraft and freezes, forming growths of ice that build up on the front edge of the wing. These ice accretions can significantly change the aerodynamic shape of the wing, affecting the pilot's ability to maneuver the aircraft.
Understanding the icing phenomenon will help engineers design countermeasures to prevent or lessen its effects. That's where Dr. Alric Rothmayer of Iowa State University's Aerospace Engineering and Engineering Mechanics department comes in.
Rothmayer has been studying the physics of icing for a number of years. He received cooperative grants from the Iowa Space Grant Consortium in 1997 and 1998 to study ice formation on planar surfaces and then began working with NASA's Aircraft Icing Team as part of a comprehensive NASA research effort.
Iowa State University's contribution to the Aircraft Icing Team has focused on certain elements of the physics modeling for use in aircraft icing codes--specifically, the problem associated with water transport, ice growth and shape formation at the ice surface. Rothmayer's work on new models and codes eventually will be used for the design and certification of both civilian and military aircraft.
Research on aircraft icing began during World War II, when the government built a wind tunnel to study icing on military aircraft at NASA's
Glenn Research Center
(formerly Lewis Research Center).
Interest has grown during the last 15 years because
of accidents that have occurred in civilian aviation. Rothmayer cites,
as one example, the 1994 crash of a commuter plane in Indiana in which
68 passengers and crew members died.
"Our goal," Rothmayer says, "is to develop computer
models that will predict how ice will form at the surface--where and how
much." As Rothmayer notes, "Where the ice freezes and how much moves
along the surface can play a big role in determining the final shape of
the ice, and that final shape can have a big effect on the handling characteristics
of aircraft."
If researchers can predict the distribution of ice
on the aircraft surface, then appropriate countermeasures can be taken,
such as installing thermal protection systems. Despite the fact that
these mathematical models are far from complete, the research group at
ISU has made considerable progress in understanding many important aspects
of the icing problem.
NASA recently recognized ISU's contributions to
the Aircraft Icing Team's efforts with a Revolutionize Aviation Goal Award
for 2001. NASA officials credited the Aircraft Icing Project Team,
in collaboration with internal and external partners, with making "substantial
progress toward eliminating icing as a safety hazard to aircraft."
The Aircraft Icing Team consists of researchers at
NASA Glenn Research Center,
NASA Ames Research Center,
Ohio Aerospace Institute,
InDyne Inc.,
U.S. Army,
Federal Aviation Administration,
Airline Pilots Association,
Meteorological Service of Canada,
National Research Council of Canada,
National Center for Atmospheric
Research,
University of Illinois at Urbana Champaign,
Iowa State University,
Massachusetts Institute of Technology,
Ohio State University,
Wichita State University,
University of Oregon, and
Mississippi State University.