Experimental study of full-scale iced-airfoil aerodynamic performance using sub-scale simulations

ice accretion;iced airfoil;sub-scale simulation

Busch, Greg T.

关键词: ice accretion;    iced airfoil;    sub-scale simulation;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/14714/1_Busch_Greg.pdf?sequence=2&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Determining the aerodynamic effects of ice accretion on aircraft surfaces is an important step in aircraft design and certification. The goal of this work was to develop a complete sub-scale wind tunnel simulation methodology based on knowledge of the detailed iced-airfoil flowfieldthat allows the accurate measurement of aerodynamic penalties associated with the accretion of ice on an airfoil and to validate this methodology using full-scale iced-airfoil performancedata obtained at near-flight Reynolds numbers. In earlier work, several classifications of iceshape were developed based on key aerodynamic features in the iced-airfoil flowfield: iceroughness, streamwise ice, horn ice, and tall and short spanwise-ridge ice. Castings of eachof these classifications were acquired on a full-scale NACA 23012 airfoil model and the aero-dynamic performance of each was measured at a Reynolds number of 12.0 x 10^6 and a Machnumber = 0.20. In the current study, sub-scale simple-geometry and 2-D smooth simulationsof each of these castings were constructed based on knowledge of iced-airfoil flowfields. Theeffects of each simulation on the aerodynamic performance of an 18-inch chord NACA 23012 airfoil model was measured in the University of Illinois 3 x 4 ft. wind tunnel at a Reynoldsnumber of 1.8 x 10^6 and a Mach number of 0.18 and compared with that measured for thecorresponding full-scale casting at high Reynolds number. Geometrically-scaled simulationsof the horn-ice and tall spanwise-ridge ice castings modeled Cl,max to within 2% and Cd,minto within 15%. Good qualitative agreement in the Cp distributions suggests that importantgeometric features such as horn and ridge height, surface location, and angle with respectto the airfoil chordline were appropriately modeled. Geometrically-scaled simulations of the ice roughness, streamwise ice, and short-ridge ice tended to have conservative Cl,max andCd. The aerodynamic performance of simulations of these types of accretion was found to besensitive to roughness height and concentration. Scaled roughness heights smaller than those found on the casting were necessary to improve simulation accuracy, resulting in Cl,max andCd,min within 3% and 5% of the casting, respectively.