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Research Papers: Flows in Complex Systems

Flow Patterns and Aerodynamic Performance of Unswept and Swept-Back Wings

[+] Author and Article Information
Shun C. Yen1

Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung, Taiwan 202, R.O.C.scyen@mail.ntou.edu.tw

Lung –C. Huang

Department of Mechanical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan 106, R.O.C.

1

Corresponding author.

J. Fluids Eng 131(11), 111101 (Oct 19, 2009) (10 pages) doi:10.1115/1.4000260 History: Received March 07, 2009; Revised July 30, 2009; Published October 19, 2009

The effects of sweep-back angle (Λ), Reynolds number (Re), and angle of attack (α) on the boundary-layer flow structures and aerodynamic performance of a finite swept-back wing were experimentally investigated. The Reynolds number and sweep-back angle used in this test is 30,000<Re<130,000 and 0degΛ45deg. The wing model was made of stainless steel, and the wing airfoil is NACA 0012. The chord length is 6 cm, and the semiwing span is 30 cm; and therefore, the semiwing aspect ratio is 5. The boundary-layer flow structures were visualized using the surface oil-flow technique. Seven boundary-layer flow modes were categorized by changing Re and α. A six-component balance is used to determine aerodynamic loadings. The aerodynamic performance is closely related to the boundary-layer flow modes. The stall angle of attack (αstall) is deferred from 9 deg to 10 deg (for an unswept wing), to 30 deg to 35 deg (for a swept-back wings of Λ>30deg). The deferment of αstall is induced from the increased rotation energy and turbulent intensity generated from the secondary flow. Furthermore, the increased rotation energy and turbulent intensity resisted the reverse pressure generated at high α.

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Copyright © 2009 by American Society of Mechanical Engineers
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References

Figures

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Figure 9

Distributions of (a) change rate of lift coefficient relative to angle of attack (dCL/dα) against Reynolds number (Re), and (b) dCL/dα as a function of sweep-back angle (Λ)

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Figure 10

Distributions of (a) maximum lift-drag ratio (CL/CD)max and (b) lift-drag ratio at stall point (CL/CD)stall as the functions of sweep-back angle (Λ) at Re=4.6×104

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Figure 11

Distributions of (a) angle of attack (α)be, (b) lift coefficient (CL)be, and (c) drag coefficient (CD)be at stall point as the functions of sweep-back angle (Λ), where the suffix, be, means the bubble extension mode

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Figure 12

Distributions of (a) angle of attack (α)stall, (b) lift coefficient (CL)stall, and (c) drag coefficient (CD)stall at stall point as the functions of sweep-back angle (Λ)

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Figure 8

Distributions of (a) lift coefficient (CL), (b) drag coefficient (CD), and (c) lift-drag ratio (CL/CD) as the functions of angle of attack (α) at Re=4.6×104

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Figure 7

Distributions of (a) lift-drag ratio (CL/CD) versus angle of attack (α), and (b) drag coefficient (CD) versus lift coefficient (CL) at Λ=0 deg. Distributions of (c) CL/CD versus α, and (d) CD versus CL at Λ=30 deg; Re=4.6×104.

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Figure 6

Distributions of (a) lift coefficient (CL), (b) drag coefficient (CD), and (c) quarter-chord moment coefficient (CM) versus angle of attack (α) at Λ=0 deg. Distributions of (d) CL versus α, (e) CD versus α, and (f) CM versus α at Λ=30 deg; Re=4.6×104.

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Figure 5

(a) Distributions of normalized reattachment position (xr′/C) and normalized separation position (xs′/C) as the functions of angle of attack (α), and (b) distribution of normalized bubble length (Lb/C) versus α; Re=4.6×104

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Figure 4

Distributions of boundary-layer flow modes

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Figure 3

Schematic sketches of surface oil-flow patterns

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Figure 2

Surface oil-flow patterns at Re=4.6×104

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Figure 1

Experimental setup

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