Researchers and a technician from the NASA Glenn Research Center traveled to the Office National d’Etudes et de Recherches Aerospatiales (ONERA) F1 wind tunnel facility in Le Fauga-Mauzac, France, to conduct full-scale, flight Reynolds number aerodynamic wind tunnel tests of an ice-contaminated airfoil. The objectives of the tests were to provide a better understanding of the effects of ice accretions on airfoil aerodynamic performance and to provide a benchmark database for iced-airfoil computational fluid dynamics (CFD) development. This study was part of a larger joint NASA-ONERA international agreement (which included important technical contributions from the University of Illinois at Urbana Champaign) to investigate ice-contaminated airfoil aerodynamics using a flow-physics-based approach. This is the first-ever, fundamental-aerodynamics-based approach to investigating the effects of aircraft icing.
In the F1 tests, a full-scale NACA-23012 airfoil was fitted with ice shapes made from molds of ice accreted on a similar airfoil model in NASA’s Icing Research Tunnel (IRT). The IRT model was subjected to conditions that might be experienced by a commuter aircraft flying in natural icing. The conditions were selected to generate ice accretions resulting in fundamentally different airfoil aerodynamics. The F1 wind tunnel is unique in that it is large enough to allow aerodynamic performance testing of a full-scale model over a large range of angles of attack, including stall, and in that it can be pressurized, allowing independent studies of Mach and Reynolds number effects.
Full-scale NACA-23012 airfoil model in the ONERA F1 tunnel.
Primarily because of concerns about aerodynamic scaling of ice-contaminated surfaces, questions have remained regarding aerodynamic performance results in smaller wind tunnels with subscale models. Results from the recently completed F1 aerodynamic performance tests largely verify previous results from the smaller tunnels, showing decreases in maximum lift coefficient of as much as 70 percent, decreases in stall angle of as much as 12° angle of attack, and increases in drag coefficient of as much as 400 to 1000 percent. These data not only provide a better understanding of the aerodynamic effects of ice accretions and a benchmark database for CFD, but they will be used to verify and validate subscale iced-aerodynamic performance testing. Where subscale testing is lacking, these results can be used to develop new, valid methods of subscale iced-aerodynamic performance testing.
A second set of tests was conducted in the F1 tunnel in June 2007. During these tests, particle imaging velocimetry (PIV) measurements were made of the airflow around the model with one of the ice shapes installed. These measurements provided flowfield details leading to a better understanding of iced aerodynamics and supplied information needed for iced CFD validation and development, which could not be obtained during the aerodynamic performance tests. Remaining work in the program consists of CFD code development and validation exercises as well as subscale testing to validate and further refine the experimental methods developed.
Glenn Contacts: Harold E. (Gene) Addy, Jr., 216-977-7467, Gene.Addy@nasa.gov, Dr. Mark G. Potapczuk, 216-433-3919, Mark.G.Potapczuk@nasa.govLast updated: October 6, 2008
Responsible NASA Official:
Gynelle.C.Steele@nasa.gov, 216-433-8258
Point of contact for NASA Glenn's Research & Technology reports: Cynthia.L.Dreibelbis@nasa.gov, 216-433-2912
Web page curator: Nancy.L.Obryan@nasa.gov (Wyle Information Systems, Inc.)
