DRA/NASA/ONERA Collaboration on Icing Research Part II-Prediction of Airfoil Ice Accretion

TITLE AND SUBTITLE:
DRA/NASA/ONERA Collaboration on Icing Research Part II-Prediction of Airfoil Ice Accretion

AUTHOR(S):
William B. Wright, R.W. Gent, and Didier Guffond

REPORT DATE:
May 1997

FUNDING NUMBERS:
WU-548-20-23
C-NAS3-27186

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
NYMA, Inc.
2001 Aerospace Parkway
Brook Park, Ohio 44142

PERFORMING ORGANIZATION REPORT NUMBER:
E-10769

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-202349

SUPPLEMENTARY NOTES:
William B. Wright, NYMA, Inc.; R.W. Gent, Defence Research Agency, Farnborough Hampshire, England; and Didier Guffond, Office National D'etudes Et de Recherches Aerospatiales, Chatillion, France. Project Manager, Haeok S. Lee, Turbomachinery and Propulsion Systems Division, NASA Lewis Research Center, organization code 5840, (216) 433-3900.

ABSTRACT:
This report presents results from a joint study by DRA, NASA, and ONERA for the purpose of comparing, improving, and validating the aircraft icing computer codes developed by each agency. These codes are of three kinds: 1) water droplet trajectory prediction, 2) ice accretion modeling, and 3) transient electrothermal deicer analysis. In this joint study, the agencies compared their code predictions with each other and with experimental results. These comparison exercises were published in three technical reports, each with joint authorship. DRA published and had first authorship of Part I-Droplet Trajectory Calculations, NASA of Part II-Ice Accretion Prediction, and ONERA of Part III-Electrothermal Deicer Analysis. The results cover work done during the period from August 1986 to late 1991. As a result, all of the information in this report is dated. Where necessary, current information is provided to show the direction of current research. In this present report on ice accretion, each agency predicted ice shapes on two dimensional airfoils under icing conditions for which experimental ice shapes were available. In general, all three codes did a reasonable job of predicting the measured ice shapes. For any given experimental condition, one of the three codes predicted the general ice features (i.e., shape, impingement limits, mass of ice) somewhat better than did the other two. However, no single code consistently did better than the other two over the full range of conditions examined, which included rime, mixed, and glaze ice conditions. In several of the cases, DRA showed that the user's knowledge of icing can significantly improve the accuracy of the code prediction. Rime ice predictions were reasonably accurate and consistent among the codes, because droplets freeze on impact and the freezing model is simple. Glaze ice predictions were less accurate and less consistent among the codes, because the freezing model is more complex and is critically dependent upon unsubstantiated heat transfer and surface roughness models. Thus, heat transfer prediction methods used in the codes became the subject for a separate study in this report to compare predicted heat transfer coefficients with a limited experimental database of heat transfer coefficients for cylinders with simulated glaze and rime ice shapes. The codes did a good job of predicting heat transfer coefficients near the stagnation region of the ice shapes. But in the region of the ice horns, all three codes predicted heat transfer coefficients considerably higher than the measured values. An important conclusion of this study is that further research is needed to understand the finer details of the glaze ice accretion process and to develop improved glaze ice accretion models.

SUBJECT TERMS:
Aircraft icing; Aeronautics; Aerodynamics

NUMBER OF PAGES:
52

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