Abstract

Flow control devices have been introduced in the wind energy sector to improve the aerodynamic behavior of the wind turbine blades (WTBs). Among these flow control devices, Gurney flaps (GFs) have been the focus of innovative research, due to their good characteristics which enhance the lift force that causes the rotation of the wind turbine rotor. The lift force increment introduced by GFs depends on the physical characteristics of the device and the angle of attack (AoA) of the incoming wind. Hence, despite a careful and detailed design, the real performance of the GFs is conditioned by an external factor, the wind. In this paper, an active operation of GFs is proposed in order to optimize their performance. The objective of the active Gurney flap (AGF) flow control technique is to enhance the aerodynamic adaption capability of the wind turbine and, thus, achieve an optimal operation in response to fast variations in the incoming wind. In order to facilitate the management of the information used by the AGF strategy, the aerodynamic data calculated by computational fluid dynamics (CFD) are stored in an artificial neural network (ANN). Blade element momentum (BEM) based calculations have been performed to analyze the aerodynamic behavior of the WTBs with the proposed AGF strategy and calculate the corresponding operation of the wind turbine. Real wind speed values from a meteorological station in Salt Lake City, Utah, USA, have been used for the steady BEM calculations. The obtained results show a considerable improvement in the performance of the wind turbine, in the form of an enhanced generated energy output value and a reduced bending moment at the root of the WTB.

Highlights

  • Renewable energy generation systems have emerged as a necessity in the current energy production and distribution infrastructure, in which fossil fuel-based sources are still the major energy suppliers

  • It can be seen that remarkably big wind speed peak values have been measured. This means that the system will have to face very fast changes in its operating point, which is a suitable scenario to analyze the effect of the active Gurney flap (AGF) flow control strategy introduced in this paper to optimize the fast dynamics of the wind turbine

  • A novel flow control strategy referred as AGF was proposed to improve the performance of the wind turbines in cases of fast variations of the operating point caused by fast variations in the incoming wind

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Summary

Introduction

Renewable energy generation systems have emerged as a necessity in the current energy production and distribution infrastructure, in which fossil fuel-based sources are still the major energy suppliers. Aramendia et al [19] presented a parametrical analysis of the influence of the length of the GF in the aerodynamic behavior of a DU91W(2)250 airfoil, which is widely used in the design of WTBs. Passive flow control devices have been studied for the aerodynamic performance enhancement of helicopters. The parametric analysis carried out by Aramendia et al [19] showed that the aerodynamic performance of WTBs with GFs placed on their surface depends on the length of the flow control device and on the angle of attack (AoA) of the incoming wind. In order to analyze the effect of the proposed AGF flow control technique on the operation of the wind turbine and evaluate its performance, blade element momentum (BEM) based calculations have been carried out, as introduced in the work of Fernandez-Gamiz et al [13].

Wind Speed Characterization
Blade Element Momentum Improvement
Results and Discussion
Conclusions
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