Towards 20MW Wind Turbine: High Reynolds Number Effects on Rotor Design

Ceyhan, O.

doi:10.2514/6.2012-1157

Cited by 25 publications

(10 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, there are much many parameters to optimize accounting for the wind turbine configuration (rotating blades, variable wind intensity, pitch and variable blade cross section, and etc). As a rotating machine, the maximum Reynolds number of a wind turbine is proportional to the blade radius (it reaches up to Re = 25 × 10 6 in giant windmills) . In these cases, airfoils exhibit better performance, such as higher lift coefficient and lower drag ones, resulting in larger lift‐to‐drag ratio at a given angle of attack .…”

Section: Discussionmentioning

confidence: 99%

“…As a rotating machine, the maximum Reynolds number of a wind turbine is proportional to the blade radius (it reaches up to Re = 25 × 10 6 in giant windmills) . In these cases, airfoils exhibit better performance, such as higher lift coefficient and lower drag ones, resulting in larger lift‐to‐drag ratio at a given angle of attack . However, to succeed in this performance improvement, one has to design VG's height according to the local boundary layer thickness.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical/experimental investigations on reducing drag penalty of passive vortex generators on a NACA 4415 airfoil

2019

View full text Add to dashboard Cite

A study emphasizing the effects of passive vortex generators (VGs) on aerodynamic characteristics of a NACA 4415 airfoil is presented. Both experimental and numerical works have been carried out on an array of VGs attached to a NACA 4415 airfoil. Lift and drag measurements are made at various angles of attack by using three-axis component balance system. On the numerical side, Reynolds-averaged Navier-Stokes (RANS) equations have been solved with ANSYS FLUENT 14.5 commercial code with fully structured mesh and three turbulence models (realizable k-ε, k-ω shear stress transport [SST] and the Spalart-Allmaras model) at Reynolds number Re = 2 × 10 5 .Parametric studies have been conducted to find out optimal configurations with respect to span-wise separation distance between VGs, along with their location along the chord. A very good agreement has been obtained between experimental and computational results indicating that this optimized configuration is robust for the considered parameters. It turns out that increasing the span-wise separation length increases the aerodynamic performances (lift-to-drag ratio) at low attack angles for which low parasitic drag is achieved but conversely degrades it at higher ones. For the stream-wise location along the chord, upstream position of VGs degrades the lift-to-drag ratio at low attack angles and conversely improves it at higher ones. KEYWORDS computational fluid dynamics, flow control, NACA 4415 airfoil, passive vortex generators, Spalart-Allmaras turbulence model, wind tunnel 1 | INTRODUCTIONOwing to the continuous increase in energy consumption and persisting demand from governments and citizens for a more sustainable energy production the wind energy has experienced considerable growth in the past decade.The prospects and main challenges of wind applications are to reach the target of 1000 GW of wind energy by 2030. 1 For the offshore market, this has led to race in building the largest wind turbines, but one now faces critical limits from a technical point of view along with prohibitive prices toward the goal to reduce the energy cost for the end-user (CoE). 2,3 For the onshore market, size upgrade is not a promising strategy owing to environmental issues related to higher noise levels and visual inconveniences. Therefore, for this latter market, engineers investigate the way to increase the aerodynamic efficiency from classical wind turbines. However, studying aerodynamic performance of full size wind turbine remains a difficult task since relevant metrology in rotating frame of such sizes is incredibly expensive and difficult. On the computational fluid dynamics side, their related large size 3-D highly turbulent flows around moving bodies are also very challenging, so very few works have been published up to now. 4

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Numerical/experimental investigations on reducing drag penalty of passive vortex generators on a NACA 4415 airfoil

2019

View full text Add to dashboard Cite

show abstract

“…Therefore, it is beneficial to design airfoils with performance that is as stable as possible. Because the flow around the blade is generally incompressible, the effects of the Mach number can be neglected . In this study, the stability of airfoil performance to Re and surface roughness is taken into considerations, and the following definition is proposed:

S = \frac{∣ p^{'} - p ∣}{p} \times 100 % .

…”

Section: Design Considerations and Prediction Methodsmentioning

confidence: 99%

Overall design optimization of dedicated outboard airfoils for horizontal axis wind turbine blades

Yang

Liao

et al. 2018

Wind Energy

View full text Add to dashboard Cite

Designing the primary airfoils for the outboard part of wind turbine blades is a complicated problem of balancing structural, aerodynamic, and acoustic requirements. This paper presents an optimization method for the overall performance of outboard wind turbine airfoils. Based on the complex flow characteristics of the rotor blades and the varying requirements along the span of a blade, the design principles of outboard airfoils were investigated. The requirements for improving the structural performance and reducing the aerodynamic noise were combined with the following aerodynamic design considerations: high efficiency, low extreme loads, stability, and a wide operating region. Thus, this paper proposes a new mathematical model for overall airfoil optimization using the airfoil performance evaluation indicators. Then, an integrated optimization design platform is established for outboard airfoils. Through 2 design cases, new airfoils with desirable aerodynamic characteristics and improved overall performance were obtained.Comparisons between the new airfoils and reference airfoils based on numerical predictions indicate that the proposed method with the newly established mathematical model can effectively balance the complex requirements of the airfoil and improve its overall performance. More notably, the design cases also indicate that the established optimization design method can be used to address special designs of outboard airfoils for different blade requirements. KEYWORDS evaluation parameters, horizontal axis wind turbine, integrated design platform, numerical optimization method, outboard airfoils, overall performance 1 | INTRODUCTION Dedicated airfoils for horizontal axis wind turbines (HAWTs) have evolved over the past several decades and have received increasing attention in recent years because of the increasingly complex aerodynamic and structural requirements of the rotor blades. The airfoil is the profile of the blade cross section, and its performance determines the energy capture performance of the blade. Special airfoils for wind turbines were initially designed in the 1980s. 1 Later, they were intensively developed by the National Renewable Energy Laboratory (NREL), 2 TU Delft, 3 and RISØ, 4 and they have recently nearly replaced traditional aviation airfoils in blade designs. However, with the development of upscaling rotor blades and regional wind farms, the efficient design of special blades operating in different conditions requires advanced airfoils with improved overall performance.Specifically, design methods for improving the overall airfoil performance need to be developed.The early airfoils specially created for wind turbines were designed using the inverse method. 5,6 With the help of subsonic, low Re flow solvers, 7-9 researchers developed some commonly used wind turbine airfoils. However, the inverse design method cannot effectively address the multiobjective design problem. The objectives mainly focused on several aerodynamic force coefficients, such as c l,design or l/d max ...

show abstract

“…Nevertheless, in order to insure that turbine size, hence its power, will continue to increase in the same fashion as it has in the last two decades, a simple modified upscale of current turbines will not be enough. But, significant technological advancement and change in the design are required to build turbines that are cost 1 efficient [4] [5]. Apart from the previous research axis that builds upon the current wind turbine structure, another axis looks for structures that are able to extract wind energy at high altitudes: "HAWE: High-Altitude Wind Energy".…”

Section: Introductionmentioning

confidence: 99%

Kite Generator System Modeling and Grid Integration

Ahmed

Hably

Bacha

2013

IEEE Trans. Sustain. Energy

View full text Add to dashboard Cite

International audienceThis paper deals principally with the grid connection problem of a kite-based system, named the "Kite Generator System (KGS)." It presents a control scheme of a closed-orbit KGS, which is a wind power system with a relaxation cycle. Such a system consists of a kite with its orientation mechanism and a power transformation system that connects the previous part to the electric grid. Starting from a given closed orbit, the optimal tether's length rate variation (the kite's tether radial velocity) and the optimal orbit's period are found. The trajectory-tracking problem is not considered in this paper; only the kite's tether radial velocity is controlled via the electric machine rotation velocity. The power transformation system transforms the mechanical energy generated by the kite into electrical energy that can be transferred to the grid. A Matlab/simulink model of the KGS is employed to observe its behavior, and to insure the control of its mechanical and electrical variables. In order to improve the KGS's efficiency in case of slow changes of wind speed, a maximum power point tracking (MPPT) algorithm is proposed

show abstract

Towards 20MW Wind Turbine: High Reynolds Number Effects on Rotor Design

Cited by 25 publications

References 8 publications

Numerical/experimental investigations on reducing drag penalty of passive vortex generators on a NACA 4415 airfoil

Numerical/experimental investigations on reducing drag penalty of passive vortex generators on a NACA 4415 airfoil

Overall design optimization of dedicated outboard airfoils for horizontal axis wind turbine blades

Kite Generator System Modeling and Grid Integration

Contact Info

Product

Resources

About