The Performance Test of Three Different Horizontal Axis Wind Turbine (HAWT) Blade Shapes Using Experimental and Numerical Methods

Fei-Bin Hsiao,Chi-Jeng Bai,Wen-Tong Chong

doi:10.3390/en6062784

Fei-Bin Hsiao, Chi-Jeng Bai + Show 1 more

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https://doi.org/10.3390/en6062784

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Journal: Energies	Publication Date: Jun 5, 2013
Citations: 81	License type: CC BY 3.0

Affiliation: National Cheng Kung University, University of Malaya

Abstract

Three different horizontal axis wind turbine (HAWT) blade geometries with the same diameter of 0.72 m using the same NACA4418 airfoil profile have been investigated both experimentally and numerically. The first is an optimum (OPT) blade shape, obtained using improved blade element momentum (BEM) theory. A detailed description of the blade geometry is also given. The second is an untapered and optimum twist (UOT) blade with the same twist distributions as the OPT blade. The third blade is untapered and untwisted (UUT). Wind tunnel experiments were used to measure the power coefficients of these blades, and the results indicate that both the OPT and UOT blades perform with the same maximum power coefficient, Cp = 0.428, but it is located at different tip speed ratio, λ = 4.92 for the OPT blade and λ = 4.32 for the UOT blade. The UUT blade has a maximum power coefficient of Cp = 0.210 at λ = 3.86. After the tests, numerical simulations were performed using a full three-dimensional computational fluid dynamics (CFD) method using the k-ω SST turbulence model. It has been found that CFD predictions reproduce the most accurate model power coefficients. The good agreement between the measured and computed power coefficients of the three models strongly suggest that accurate predictions of HAWT blade performance at full-scale conditions are also possible using the CFD method.

Highlights

For a horizontal-axis wind turbine (HAWT) system, the efficiency of the system transformation is related to the blade shape
The untapered and optimum twist (UOT) blade obtained a maximum Cp value of 0.428, while the tip speed ratio is 4.32. Both the OPT and the OUT blades obtain an excellent power coefficient, we conclude that the OPT blade is better than the UOT blade because it has a higher range of high power coefficients
The wind tunnel test results presented in this paper show that the OPT and the UOT blades obtain the same maximum power coefficient (Cp = 0.428) but at different tip speed ratio points

Summary

Introduction

For a horizontal-axis wind turbine (HAWT) system, the efficiency of the system transformation is related to the blade shape. Blade element momentum (BEM) theory is widely used when designing a HAWT blade shape and predicts its performance using a fairly simple procedure [1]. This theory requires combining the two-dimensional (2D) airfoil data to obtain the optimum blade shape, including the distributions of chord length and the twist angle along the span-wise direction. If the optimal blade is operated at a different tip speed ratio than the one for which it has been designed, it will no longer be optimal [1,2]. The purpose of this study is to construct a HAWT system with variable-speed operation in which the optimum blade is determined using BEM theory. Two other blades are considered, as will be discussed later

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Conclusion