• Title/Summary/Keyword: wind turbine blades

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Power Coefficient and Pressure Distributions on Blade Surfaces of a Wind Turbine with Tiltable Blades by 3D Simulations (날개 틸팅형 풍력발전기의 출력과 날개 표면의 압력분포에 대한 3차원 유동 해석)

  • Jeong, Chang-Do;Bae, Hyunwoo;Sung, Jaeyong
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.16 no.1
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    • pp.1-8
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    • 2020
  • In this study, a new shape of wind turbine with horizontal axis has been proposed. The proposed wind turbine has two pairs of 3 tiltable blades which minimizes air resistance during the reverse rotational direction. Under a given wind speed, 3D numerical simulations on tiltable blades were performed for various TSRs(tip-speed-ratios). Four cases of rotational position was considered to analyze the torque and wind power generated on the blade surfaces. The results show that the maximum wind power occurs at the TSR of 0.2. Due to the blade tilting, the wind passes through the blade without air resistance at the reverse rotational direction. The torque is mainly caused by pressure differences between the front and rear surface of the blade, and it becomes maximum when the blade is located at the azimuth angle of 330°.

Aerodynamic characteristics of a vertical axis wind turbine blade (수직축 풍력터빈 블레이드의 공기역학적 특성)

  • Shin, Jee-Young;Son, Young-Seok;Cha, Duk-Guen;Lee, Cheol-Gyun;Hwang, I-Cheol
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.8
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    • pp.877-884
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    • 2006
  • The objective of this study is to investigate the aerodynamic characteristics of a vertical axis wind turbine blade as the basic study of a design of a vertical axis wind turbine. The lift and drag coefficients of the various shape of the vortical axis wind turbine blades are analyzed and compared using the CFD code Fluent. To validate the numerical analysis, the predicted results of the Fluent are compared with those of the Xfoil code and the experimental results. We conclude that the program Fluent can be used to predict the aerodynamics of the wind turbine blade. By comparing the predicted results of the aerodynamic characteristics of the different shape of the blades, an appropriate shape of the blade is suggested to design the vortical axis wind turbine blade.

Long-term simulation of wind turbine structure for distributed loading describing long-term wind loads for preliminary design

  • Ibrahimbegovic, Adnan;Boujelben, Abir
    • Coupled systems mechanics
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    • v.7 no.2
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    • pp.233-254
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    • 2018
  • In order to reduce the dependency on fossil fuels, a policy to increase the production capacity of wind turbine is set up. This can be achieved with increasing the dimensions of offshore wind turbine blades. However, this increase in size implies serious problems of stability and durability. Considering the cost of large turbines and financial consequences of their premature failure, it is imperative to carry out numerical simulations over long periods. Here, an energy-conserving time-stepping scheme is proposed in order to ensure the satisfying computation of long-term response. The proposed scheme is implemented for three-dimensional solid based on Biot strain measures, which is used for modeling flexible blades. The simulations are performed at full spatial scale. For reliable design process, the wind loads should be represented as realistically as possible, including the fluid-structure interaction (FSI) dynamic effects on wind turbine blades. However, full-scale 3D FSI simulations for long-term wind loading remain of prohibitive computation cost. Thus, the model to quantify the wind loads proposed here is a simple, but not too simple to be representative for preliminary design studies.

Study on Design, Manufacturing and Test Evaluation using Composite Materials of Vertical Axis Wind Turbine Blade (수직축 풍력 블레이드의 복합재 적용 설계, 제작 및 시험 평가 연구)

  • Park, Hyunbum
    • Journal of Aerospace System Engineering
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    • v.12 no.3
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    • pp.58-63
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    • 2018
  • This work dealt with the design and manufacturing of composite blades of a vertical axis wind turbine system. In this work, aerodynamic and structural designs of sandwich composite blades for a vertical axis wind turbine system were performed. First, the aerodynamic and structural design requirements of the composite blades were investigated. After the structural design was complete, a structural analysis of the wind turbine blades was performed using the finite element analysis method. It was performed with the stress and displacement analysis at the applied load condition. A design modification for the structurally weak part was proposed as a result of the structural analysis. Through another structural analysis, it was confirmed that the final designed blade structure is safe.

Aerodynamic analysis and control mechanism design of cycloidal wind turbine adopting active control of blade motion

  • Hwang, In-Seong;Lee, Yun-Han;Kim, Seung-Jo
    • International Journal of Aeronautical and Space Sciences
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    • v.8 no.2
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    • pp.11-16
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    • 2007
  • This paper describes the cycloidal wind turbine, which is a straight blade vertical axis wind turbine using the cycloidal blade system. Cycloidal blade system consists of several blades rotating about an axis in parallel direction. Each blade changes its pitch angle periodically. Cycloidal wind turbine is different from the previous turbines. The wind turbine operates with optimum rotating forces through active control of the blade to change pitch angle and phase angle according to the changes of wind direction and wind speed. Various numerical experiments were conducted to develop a small vertical axis wind turbine of 1 kW class. For this numerical analysis, the rotor system equips four blades consisting of a symmetric airfoil NACA0018 of 1.0m in span, 0.22m in chord and 1.0m in radius. A general purpose commercial CFD program, STAR-CD, was used for numerical analysis. PCL of MSC/PATRAN was used for efficient parametric auto mesh generation. Variables of wind speed, pitch angle, phase angle and rotating speed were set in the numerical experiments. The generated power was obtained according to the various combinations of these variables. Optimal pitch angle and phase angle of cycloidal blade system were obtained according to the change of the wind direction and the wind speed. Based on data obtained from the above analysis, control device was designed. The wind direction and the wind speed were sensed by a wind indicator and an anemometer. Each blades were actuated to optimal performance values by servo motors.

A Study on Development and Analysis for Wind Turbine Blades Using Composites Materials (경량화 복합재를 이용한 풍력 블레이드 개발과 해석에 관한 연구)

  • Kang, Byong-Yun;Han, Jeong-Young;Hong, Cheol-Hyun;Moon, Byung-Young
    • The KSFM Journal of Fluid Machinery
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    • v.14 no.2
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    • pp.59-64
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    • 2011
  • Wind turbine blades will be required to be longer, lighter, more reliable and more consistent. Therefore it is necessary to lose weight of the wind turbine blades. This points squarely toward prepreg blade production growing. It is important to note however that prepreg blade production as it is today is flawed and that there are ways to improve greatly on the performance of these blades in manufacturing process and in their in-service performance. Through this, we have some detail on the current process and its advantage of cost and weight of blades.

Active load control for wind turbine blades using trailing edge flap

  • Lee, Jong-Won;Kim, Joong-Kwan;Han, Jae-Hung;Shin, Hyung-Kee
    • Wind and Structures
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    • v.16 no.3
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    • pp.263-278
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    • 2013
  • The fatigue load of a turbine blade has become more important because the size of commercial wind turbines has increased dramatically in the past 30 years. The reduction of the fatigue load can result in an increase in operational efficiency. This paper numerically investigates the load reduction of large wind turbine blades using active aerodynamic load control devices, namely trailing edge flaps. The PD and LQG controllers are used to determine the trailing edge flap angle; the difference between the root bending moment and its mean value during turbulent wind conditions is used as the error signal of the controllers. By numerically analyzing the effect of the trailing edge flaps on the wind turbines, a reduction of 30-50% in the standard deviation of the root bending moment was achieved. This result implies a reduction in the fatigue damage on the wind turbines, which allows the turbine blade lengths to be increased without exceeding the designed fatigue damage limit.

Computational study of a small scale vertical axis wind turbine (VAWT): comparative performance of various turbulence models

  • Aresti, Lazaros;Tutar, Mustafa;Chen, Yong;Calay, Rajnish K.
    • Wind and Structures
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    • v.17 no.6
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    • pp.647-670
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    • 2013
  • The paper presents a numerical approach to study of fluid flow characteristics and to predict performance of wind turbines. The numerical model is based on Finite-volume method (FVM) discretization of unsteady Reynolds-averaged Navier-Stokes (URANS) equations. The movement of turbine blades is modeled using moving mesh technique. The turbulence is modeled using commonly used turbulence models: Renormalization Group (RNG) k-${\varepsilon}$ turbulence model and the standard k-${\varepsilon}$ and k-${\omega}$ turbulence models. The model is validated with the experimental data over a large range of tip-speed to wind ratio (TSR) and blade pitch angles. In order to demonstrate the use of numerical method as a tool for designing wind turbines, two dimensional (2-D) and three-dimensional (3-D) simulations are carried out to study the flow through a small scale Darrieus type H-rotor Vertical Axis Wind Turbine (VAWT). The flows predictions are used to determine the performance of the turbine. The turbine consists of 3-symmetrical NACA0022 blades. A number of simulations are performed for a range of approaching angles and wind speeds. This numerical study highlights the concerns with the self-starting capabilities of the present VAWT turbine. However results also indicate that self-starting capabilities of the turbine can be increased when the mounted angle of attack of the blades is increased. The 2-D simulations using the presented model can successfully be used at preliminary stage of turbine design to compare performance of the turbine for different design and operating parameters, whereas 3-D studies are preferred for the final design.

Numerical Study of the blade dynamics for a cross-flow turbine

  • Sato Yuko;Kawamura Tetuya
    • 한국전산유체공학회:학술대회논문집
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    • 2003.10a
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    • pp.230-231
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    • 2003
  • Two and three-dimensional flows around a cross-flow wind turbine are investigated by the numerical simulation. The turbine studied in this paper has cylindrical shape with many small blades along its periphery. Incompressible Navier-Stokes equation is used for this simulation. A rotating coordinate system, which rotates at the same speed of the turbine, is used in order to simplify the boundary conditions on the blades of the turbine. Additionally, a boundary fitted coordinate system is employed in order to express the shape of the blades precisely. A third order upwind scheme is chosen for the approximation of the non-linear terms. When the number of blades is about 10, the highest torque is obtained.

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Wind-induced responses and equivalent static wind loads of tower-blade coupled large wind turbine system

  • Ke, S.T.;Wang, T.G.;Ge, Y.J.;Tamura, Y.
    • Structural Engineering and Mechanics
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    • v.52 no.3
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    • pp.485-505
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    • 2014
  • This study aimed to develop an approach to accurately predict the wind models and wind effects of large wind turbines. The wind-induced vibration characteristics of a 5 MW tower-blade coupled wind turbine system have been investigated in this paper. First, the blade-tower integration model was established, which included blades, nacelle, tower and the base of the wind turbine system. The harmonic superposition method and modified blade element momentum theory were then applied to simulate the fluctuating wind field for the rotor blades and tower. Finally, wind-induced responses and equivalent static wind loads (ESWL) of the system were studied based on the modified consistent coupling method, which took into account coupling effects of resonant modes, cross terms of resonant and background responses. Furthermore, useful suggestions were proposed to instruct the wind resistance design of large wind turbines. Based on obtained results, it is shown from the obtained results that wind-induced responses and ESWL were characterized with complicated modal responses, multi-mode coupling effects, and multiple equivalent objectives. Compared with the background component, the resonant component made more contribution to wind-induced responses and equivalent static wind loads at the middle-upper part of the tower and blades, and cross terms between background and resonant components affected the total fluctuation responses, while the background responses were similar with the resonant responses at the bottom of tower.