Abstract

For a wind turbine to extract as much energy as possible from the wind, blade geometry optimization to maximize the aerodynamic performance is important. Blade design optimization includes linearizing the blade chord and twist distribution for practical manufacturing. As blade linearization changes the blade geometry, it also affects the aerodynamic performance and load characteristics of the wind turbine rotor. Therefore, it is necessary to understand the effects of the design parameters used in linearization. In this study, the effects of these parameters on the aerodynamic performance of a wind turbine blade were examined. In addition, an optimization algorithm for linearization and an objective function that applies multiple tip speed ratios to optimize the aerodynamic efficiency were developed. The analysis revealed that increasing the chord length and chord profile slope improves the aerodynamic efficiency at low wind speeds but lowers it at high wind speeds, and that the twist profile mainly affects the behaviour at low wind speeds, while its effect on the aerodynamic performance at high wind speeds is not significant. When the blade geometry was optimized by applying the linearization parameter ranges obtained from the analysis, blade geometry with improved aerodynamic efficiency at all wind speeds below the rated wind speed was derived.

Highlights

  • The purpose of a wind turbine is to produce a large amount of electrical energy by extracting as much energy as possible from the wind

  • The wind turbine blade geometry is optimized first to maximize the aerodynamic performance of the turbine [1]

  • Wind turbine blade geometry optimization is the process of determining the geometry that can generate the maximum aerodynamic efficiency or maximum energy of the wind turbine

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Summary

Introduction

The purpose of a wind turbine is to produce a large amount of electrical energy by extracting as much energy as possible from the wind. An optimal linearization method is required to minimize the aerodynamic efficiency reduction, and various blade chord and twist profile linearization methods have been proposed. Liu et al [12] proposed a linear equation that performs linearization based on the theoretical blade tip chord and twist profile for fixed-pitch, fixed-speed wind turbine blades. As the blade linearization process affects the aerodynamic performance and blade stiffness due to the geometry change, blade design optimization becomes very complicated if the structural stability of the blade is considered. To achieve the performance goals of wind turbines, optimization algorithms have been applied to blade geometry design in various studies. As the blade linearization process changes the blade geometry, it affects the aerodynamic performance and load characteristics of the wind turbine rotor. The aerodynamic performance of the blade optimized using the developed algorithm was compared with that of the NREL baseline blade to verify the performance of the proposed optimization algorithm and the suitability of the objective function

Blade Design Procedure
Initial Blade Geometry Design
Design
Blade Performance Analysis
Optimization Algorithm for Linearization
Effects of Linearization on Blade Performance
NREL 5 MW Baseline
Effects of Chord and Twist Linearization
Variation
Comparison of Aerodynamic Performance
10. Aerodynamic
Design Optimization
16. Aerodynamic
Findings
Conclusions
Full Text
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