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Research Papers

Numerical Studies of the Effects of Active and Passive Circulation Enhancement Concepts on Wind Turbine Performance

[+] Author and Article Information
Chanin Tongchitpakdee

School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, Atlanta, GA 30332-0150chaniṉtongchitpakdee@ae.gatech.edu

Sarun Benjanirat

School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, Atlanta, GA 30332-0150saruṉbenjanirat@ae.gatech.edu

Lakshmi N. Sankar

School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, Atlanta, GA 30332-0150lsankar@ae.gatech.edu

J. Sol. Energy Eng 128(4), 432-444 (Jul 16, 2006) (13 pages) doi:10.1115/1.2346704 History: Received January 24, 2006; Revised July 16, 2006

Abstract

The aerodynamic performance of a wind turbine rotor equipped with circulation enhancement technology (trailing-edge blowing or Gurney flaps) is investigated using a three-dimensional unsteady viscous flow analysis. The National Renewable Energy Laboratory Phase VI horizontal axis wind turbine is chosen as the baseline configuration. Experimental data for the baseline case is used to validate the flow solver, prior to its use in exploring these concepts. Calculations have been performed for axial and yawed flow at several wind conditions. Results presented include radial distribution of the normal and tangential forces, shaft torque, root flap moment, and surface pressure distributions at selected radial locations. At low wind speed $(7m∕s)$ where the flow is fully attached, it is shown that a Coanda jet at the trailing edge of the rotor blade is effective at increasing circulation resulting in an increase of lift and the chordwise thrust force. This leads to an increased amount of net power generation compared to the baseline configuration for moderate blowing coefficients $(Cμ⩽0.075)$. A passive Gurney flap was found to increase the bound circulation and produce increased power in a manner similar to Coanda jet. At high wind speed $(15m∕s)$ where the flow is separated, both the Coanda jet and Gurney flap become ineffective. The effects of these two concepts on the root bending moments have also been studied.

Copyright © 2006 by American Society of Mechanical Engineers
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Figures

Figure 1

Body-fitted C grid of the rotor: (a) 3D computational domain, (b) mesh in vicinity of rotor surface, (c) mesh in vicinity of trailing-edge jet slot, and (d) mesh in vicinity of gurney flap

Figure 2

Computed streamlines over the rotor at 7m∕s, 0deg yaw

Figure 7

Variation of the shaft torque at 7m∕s as a function of yaw angle with varying Cμ

Figure 8

Variation of the root flap moment at 7m∕s as a function of yaw angle with varying Cμ

Figure 9

Comparison of pressure coefficient distribution at 7m∕s, 0deg yaw, with and without blowing

Figure 10

Comparison of pressure coefficient distribution at 7m∕s, 30deg yaw, with and without blowing

Figure 11

Excess power and input power versus Cμ at 7m∕s with 0, 10, and 30deg yaw

Figure 12

Computed streamlines over the rotor at 15m∕s, 10deg yaw

Figure 13

Radial distribution of the normal force coefficient CN at 15m∕s and 10deg yaw with varying Cμ

Figure 14

Radial distribution of the tangential force coefficient CT at 15m∕s and 10deg yaw with varying Cμ

Figure 15

Excess power and input power versus Cμ at 15m∕s and 10deg yaw

Figure 16

Computed streamlines over the rotor at 7m∕s, 0deg yaw; Gurney flap case: (a) without the Gurney flap and (b) with the Gurney flap

Figure 17

Radial distribution of the normal force coefficient CN at 7m∕s; with and without a Gurney flap

Figure 18

Radial distribution of the tangential force coefficient CT at 7m∕s; with and without a Gurney flap

Figure 19

Variation of the shaft torque at 7m∕s as a function of yaw angle; with and without a Gurney flap

Figure 24

Radial distribution of the tangential force coefficient CT at 15m∕s (0 and 10deg yaw), with and without a Gurney flap

Figure 25

Variation of the shaft torque at 15m∕s, with and without a Gurney flap (At zero yaw, the Betz limit is ∼13,100Nm.)

Figure 20

Variation of the root flap moment at 7m∕s as a function of yaw angle; with and without a Gurney flap

Figure 21

Comparison of pressure coefficient distribution at 7m∕s, 0deg yaw; with and without a Gurney flap

Figure 22

Computed streamlines over the rotor at 15m∕s, 0deg yaw; Gurney flap case: (a) without the Gurney flap and (b) with the Gurney flap

Figure 23

Radial distribution of the normal force coefficient CN at 15m∕s (0 and 10deg yaw), with and without a Gurney flap

Figure 3

Azimuth variation of the normal force coefficient CN at 7m∕s, 30deg yaw, with and without blowing

Figure 4

Azimuth variation of the tangential force coefficient CT at 7m∕s, 30deg yaw, with and without blowing

Figure 6

Radial distribution of the tangential force coefficient CT at 7m∕s with varying Cμ

Figure 5

Radial distribution of the normal force coefficient CN at 7m∕s with varying Cμ

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