Influence of Boundary Layer Behavior on Aerodynamic Coefficients of a Swept-Back Wing

[+] Author and Article Information
S. C. Yen1

Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung, Taiwan 202, Republic of Chinascyen@mail.ntou.edu.tw

C. M. Hsu

Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 106, Republic of China


Corresponding author.

J. Fluids Eng 129(6), 674-681 (Dec 18, 2006) (8 pages) doi:10.1115/1.2734212 History: Received February 10, 2006; Revised December 18, 2006

The effects of the Reynolds number and angle of attack on the boundary layer and the aerodynamic performance of a finite swept-back wing are studied experimentally. The cross-sectional profile of the wing is NACA 0012 (aspect ratio=10), and the sweep-back angle is 15 deg. The Reynolds number is set in the range of 30,000–130,000. The boundary layer field is visualized with surface oil-flow techniques. Six characteristic flow regimes—laminar separation, separation bubble, leading-edge bubble, bubble burst, turbulent separation, and bluff-body wake—are categorized and studied by considering the Reynolds numbers and angles of attack. The characteristic behaviors of boundary layer significantly affect the lift, drag, and moment coefficients. The bubble length shortens significantly in the separation bubble and leading-edge bubble regimes as the angle of attack rises. The aerodynamic performances demonstrate that the swept-back wing model has no hysteresis.

Copyright © 2007 by American Society of Mechanical Engineers
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Figure 1

Experimental setup

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Figure 2

Typical surface oil-flow patterns on the suction surface of a swept-back wing at Rec=4.55×104

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Figure 3

Hand sketches of typical boundary layer patterns corresponding to Fig. 2

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Figure 4

Characteristic flow mode regimes

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Figure 5

Variation of chordwire location of separation and reattachment with (a) angle of attack and (b) chord Reynolds number

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Figure 6

Variation of chordwire location of bubble length with (a) angle of attack and (b) chord Reynolds number

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Figure 7

Aerodynamic performances of swept-back wing: (a) lift coefficient, (b) drag coefficient, and (c) moment coefficient, respectively; Rec=4.55×104 for all cases

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Figure 8

Slope of the lift coefficient and the angle of attack versus the chord Reynolds numbers

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Figure 9

(a) Lift-to-drag ratio versus the angle of attack and (b) drag coefficient versus squared lift coefficient; Rec=4.55×104

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Figure 10

Distributions of the maximum lift-to-drag ratio (circle) and lift-to-drag ratio at stalling point (square) as functions of chord Reynolds number, respectively

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Figure 11

Effect of Reynolds number on (a) stall angle of attack, (b) maximum lift coefficient, (c) stall drag coefficient, and (d) stall moment coefficient



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