LWC and Temperature Effects on Ice Accretion Formation on Swept Wings at Glaze Ice Conditions

TITLE AND SUBTITLE:
LWC and Temperature Effects on Ice Accretion Formation on Swept Wings at Glaze Ice Conditions

AUTHOR(S):
Mario Vargas and Eli Reshotko

REPORT DATE:
January 2000

FUNDING NUMBERS:
WU-548-20-23-00

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
John H. Glenn Research Center at Lewis Field
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-12059

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, DC 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-2000-209777
AIAA-2000-0483

SUPPLEMENTARY NOTES:
Prepared for the 38th Aerospace Sciences Meeting and Exhibit sponsored by the American Institute of Aeronautics and Astronautics, Reno, Nevada, January 10-13, 2000. Mario Vargas, NASA Glenn Research Center; and Eli Reshotko,
Case Western Reserve University, Department of Mechanical and Aerospace Engineering, Cleveland, Ohio 44106. Responsible person, Mario Vargas, organization code 5840, (216) 433-3943.

ABSTRACT:
An experiment was conducted to study the effect of liquid water content and temperature on the critical distance in ice accretion formation on swept wings at glaze ice conditions. The critical distance is defined as the distance from the attachment line to the beginning of the zone where roughness elements develop into glaze ice feathers. A baseline case of 150 mph, 25 °F, 0.75 g/m3 LWC and 20 mm MVD was chosen. Icing runs were performed on a NACA 0012 swept wing tip at 150 mph and MVD of 20 mm for liquid water contents of 0.5 g/m3, 0.75 g/m3, and 1.0 g/m3, and for total temperatures of 20 °F, 25 °F and 30 °F. At each tunnel condition, the sweep angle was changed from 0° to 45° in 5° increments. Casting data, ice shape tracings, and closeup photographic data were obtained. The results showed that decreasing the LWC to 0.5 g/m3 decreases the value of the critical distance at a given sweep angle compared to the baseline case, and starts the formation of complete scallops at 30° sweep angle. Increasing the LWC to 1.0 g/m3 increases the value of the critical distance compared to the baseline case, the critical distance remains always above 0 millimeters and complete scallops are not formed. Decreasing the total temperature to 20 °F decreases the critical distance with respect to the baseline case and formation of complete scallops begins at 25° sweep angle. When the total temperature is increased to 30 °F, bumps covered with roughness elements appear on the ice accretion at 25° and 30° sweep angles, large ice structures appear at 35° and 40° sweep angles, and complete scallops are formed at 45° sweep angle.

SUBJECT TERMS:
Ice formation; Swept wings; Cross flow instability

NUMBER OF PAGES:
35

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