Research Papers: Alternative Energy Sources

Shape Morphing Mechanism for Improving Wind Turbines Performance

[+] Author and Article Information
Jesus Alejandro Franco

Universidad Autonoma de Queretaro,
Cerro de las Campanas S/N,
Santiago de Querétaro 76010, Querétaro,
e-mail: jfranco15@alumnos.uaq.mx

Juan Carlos Jauregui

Universidad Autonoma de Querétaro,
Cerro de las Campanas S/N,
Santiago de Querétaro 76010, Querétaro,
e-mail: jc.jauregui@uaq.mx

Andres Carbajal

Universidad Autonoma de Querétaro,
Cerro de las Campanas S/N,
Santiago de Querétaro 76010, Querétaro,
e-mail: acarbajaldi@gmail.com

Manuel Toledano-Ayala

Universidad Autonoma de Querétaro,
Cerro de las Campanas S/N,
Santiago de Querétaro 76010, Querétaro,
e-mail: toledano@uaq.mx

1Corresponding author.

Contributed by the Advanced Energy Systems Division of ASME for publication in the JOURNAL OF ENERGY RESOURCES TECHNOLOGY. Manuscript received November 7, 2016; final manuscript received April 29, 2017; published online June 8, 2017. Assoc. Editor: Bengt Sunden.

J. Energy Resour. Technol 139(5), 051214 (Jun 08, 2017) (13 pages) Paper No: JERT-16-1450; doi: 10.1115/1.4036724 History: Received November 07, 2016; Revised April 29, 2017

Wind energy technology is facing new challenges due to the increment in rotor diameter. Nowadays, several studies focus on the development of new flow control methods for load alleviation, in order to increase the lifetime of the blades. This paper describes a shape morphing-based method for smart blades. The study includes an aerodynamic model with a computational search algorithm to find the optimal Cp. A section with shape morphing technology was developed to prove the performance of the method. The smart blade prototype section incorporates a novel structure with a flexible skin and a compliant mechanism. This deformable structure achieves the required displacements for different NACA profiles through camber morphing. In this way, the efficiency and the load variations are improved. The compliant mechanism has to be as light as possible and it has to be competitive in cost. In order to achieve these limitations, different actuating mechanisms were evaluated. Among different possibilities, servo actuators presented higher load/weight capabilities and the required displacement ratios to cover the entire deformable range. The airfoil is modified according to the wind condition and the wind speed is the input variable for controlling the actuators displacement. The control algorithm has a very high frequency response; in this way, the blade profile can be modified in a shorter time and it can respond to high wind velocity variations. Therefore, a deformable section improves the overall performance of wind turbines since it increases power and extends the lifetime of the blades.

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Fig. 1

Wind turbine coordinates system scheme

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Fig. 2

Airfoil segments according to the blade element theory: attack angle changes with the blade rotation [23]

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Fig. 3

The local velocity vector effect in the blade element theory representation

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Fig. 4

Camber morphing method, the mean camber line changes for each wind condition to reach an optimal wind turbine performance

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Fig. 5

Flux diagram of the computational iterative process

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Fig. 6

Functional structure diagram: system divided into three subsystems

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Fig. 7

The compliant mechanisms designed and analyzed to achieve the required displacements

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Fig. 8

Center point comparison between three different NACA profiles (0012, 3312, and 6612)

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Fig. 9

Model simulation strategy

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Fig. 10

Composite layup diagram: a detailed representation of the materials location and the areas reinforced in the prototype surface

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Fig. 11

Deformable sections location: QBlade® software representation of the annular disk where the sections are deformable (left) and the location of the three deformable sections in a singular blade (right)

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Fig. 12

Loads and Cp comparison between the NACA 4412 fixed blade versus the morphing blade

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Fig. 13

Load-section surfaces NACA 4412 fixed blade versus the morphing blade for different wind velocities (5–15 m/s)

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Fig. 14

Cp comparison between the algorithm developed and QBlade®

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Fig. 15

Finite element method results: trailing edge and leading edge required displacements from NACA 0012–6612

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Fig. 16

Inner section of the final prototype: 3D model representation

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Fig. 17

CFD analysis: (a) pressure distribution and (b) turbulence eddy dissipation

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Fig. 18

Coordinate measurement system for the geometrical shape morphing validation

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Fig. 19

Smart section prototype assembly for aerodynamic wind tunnel tests




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