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Research Papers

Rotor Blade Sectional Performance Under Yawed Inflow Conditions

[+] Author and Article Information
Takao Maeda

Division of Mechanical Engineering, Graduated School of Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japanmaeda@mach.mie-u.ac.jp

Division of Mechanical Engineering, Graduated School of Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japankamada@mach.mie-u.ac.jp

Jun Suzuki

Division of Mechanical Engineering, Graduated School of Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japanjun@fel.mach.mie-u.ac.jp

Hideyasu Fujioka

Division of Mechanical Engineering, Graduated School of Mie University, 1577 Kurimamachiya, Tsu, Mie 514-8507, Japanfujioka@fel.mach.mie-u.ac.jp

J. Sol. Energy Eng 130(3), 031018 (Jul 16, 2008) (7 pages) doi:10.1115/1.2931514 History: Received June 02, 2007; Revised November 26, 2007; Published July 16, 2008

Abstract

This study shows the results of pressure distribution measurements on a rotor blade of a horizontal axis wind turbine under various yawed operations. The experiments are carried out in a wind tunnel with a $2.4m$ diameter test rotor. In the measurements, the power curve and pressure distributions are measured for different azimuth angles. By increasing yaw angle, the maximum value of power coefficient of the rotor decreases. The sign of the yaw angle does not have any effect on power performance. The aerodynamic forces are discussed using the axial and rotational force coefficients for each azimuth angle. In the case of higher tip speed ratios, the blade section passing on the upstream side in yawed operations has a greater contribution to the rotor torque than that on the downstream side. In this tip speed range, the aerodynamic forces at the 70% radius section appear proportional to the angle of attack. In the case of the lower tip speed ratios, the blade on the downstream side does not contribute to rotor torque, which appears to result from separation.

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Figures

Figure 1

Experimental setup

Figure 2

Instrumentation of the rotor blade: (a) radial placement of the instrumented sections; (b) position of pressure taps (r∕R=0.7)

Figure 3

Definition of azimuth and yaw angles

Figure 4

Aerodynamic forces coefficients

Figure 5

Dynamic response of pressure tubing

Figure 6

Rotor performance distributions for various yaw angles: (a) λ‐Cpower curve; (b) λ‐Ctorque curve

Figure 7

Comparison of maximum power coefficients for various yaw angles

Figure 8

Comparison of the pressure distribution at ψ=0 for various yaw angles (r∕R=0.7)

Figure 9

Geometrical angle of attack of r∕R=0.7 for various yaw angles (λ=3.8)

Figure 10

Rotational and axial force coefficients at ψ=0 for various yaw angles (r∕R=0.7): (a) λ‐Cr curve (ψ=0); (b) λ‐Ca curve (ψ=0)

Figure 11

Pressure distribution for various λ at Φ=0(r∕R=0.7)

Figure 12

Rotational and axial force coefficients at ψ=180 for various yaw angles (r∕R=0.7): (a) λ‐Cr curve (ψ=180); (b) λ‐Ca curve (ψ=180)

Figure 13

Rotational and axial force coefficients at ψ=90 for various yaw angles (r∕R=0.7): (a) λ‐Cr curve (ψ=90); (b) λ‐Ca curve (ψ=90)

Figure 14

Rotational and axial force coefficients at ψ=270 for various yaw angles (r∕R=0.7): (a) λ‐Cr curve (ψ=270); (b) λ‐Ca curve (ψ=270)

Figure 15

Pressure distribution for various ψ at Φ=30(r∕R=0.7)

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