Aerodynamics of a swept wing with leading-edge ice at low Reynolds number

aircraft icing;swept wing icing;swept wing aerodynamics

Diebold, Jeffrey ; Bragg ; Michael B.

关键词: aircraft icing;    swept wing icing;    swept wing aerodynamics;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/34279/Diebold_Jeffrey.pdf?sequence=1&isAllowed=y

美国|英语

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

【 摘 要 】

An experimental study of the aerodynamics of a swept wing with ice at low Reynolds number has been performed. The goal of this work was to demonstrate the use of various experimental techniques applied to understanding the aerodynamic effects of a leading-edge ice simulation on a highly swept, high-aspect ratio wing. The swept wing model was a modified version of the NASA Common Research Model, designed to represent a typical wide body commercial airliner. The modified geometry of the model used in this study included a ΛLE = 35º, AR = 8.3 and λ=0.296. The experimental techniques used were force balance measurements, surface pressure measurements, surface oil flow visualization and 5-hole probe wake surveys. Tests were performed at Reynolds numbers of 3x105, 6x105 and 7.8x105 and corresponding Mach numbers of 0.08, 0.15 and 0.2.Force balance results show that the ice shape had a significant effect on performance. The stalling angle of attack and maximum lift coefficient were reduced while the drag was increased throughout the entire range of angles of attack tested. A large leading-edge vortex behind the ice shape was observed in the oil flow, and the pressure measurements showed this vortex had a significant effect on the pressure field over the wing. From the 5-hole wake survey results it was seen that the ice shape increased the profile drag while the induced drag was relatively unaffected. Using the oil flow, the evolution of the leading-edge vortex was observed and features seen in the oil flow were related to features observed in the wake. The flowfield of the iced wing contained several similarities to the flowfield of an airfoil with horn ice; however, there were several important differences due to the three-dimensional nature of the swept wing flowfield. The spanwise distribution of lift and drag were also investigated. By comparing the distributions on the clean and iced wing it was possible to determine that the ice had the largest impact on the aerodynamics of the outboard sections. It was also shown that features observed in the surface oil flow and the wake can be correlated to certain features in the lift and drag distributions. Finally, the effect of the Reynolds number was investigated. Over the range of Reynolds numbers tested, which was not representative of flight, it was observed that the Reynolds number had a reduced influence on the iced wing. This trend was observed in the performance and flowfield results.