Multielement Airfoils for Wind Turbines

Ragheb, Adam M.; Selig, Michael S.

doi:10.1016/b978-0-12-809451-8.00011-4

Cited by 4 publications

(7 citation statements)

References 24 publications

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“…The resulting lift, drag and moment coefficients as well as location of transition and separation will be presented in graphs and tables. For the profiles of the hydrokinetic turbine blades, small α are usually chosen where the lift coefficient is high and the drag coefficient is low [21]- [25]. These coefficients depend on the water velocity and, hence, on the Reynolds number, because when the viscosity forces are greater compared to the inertial forces, the effects of the friction are increased, affecting the velocities, the pressure gradient and the lift generated by the hydrodynamic profile [1]- [3], [27]- [28].…”

Section: D Javafoil Analysismentioning

confidence: 99%

“…Only, there is one work that studies the use of a double blade hydrofoil for generating the maximum lift [20]. Nevertheless, there are some numerical studies on multi-element airfoil configurations for wind turbines [21]- [25]. Additionally, in general terms, there are not studies optimizing the geometrical parameters of multi-element hydrofoils for obtaining a high lift-to-drag ratio for hydrokinetic turbine application.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of a lift augmented hydrofoil for hydrokinetic turbines

Chica¹,

Aguilar²,

Rubio-Clemente³

2024

RE&PQJ

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In the last years, increased attention has been given to hydrokinetic energy technologies due to these turbines represent an attractive technology for the harnessing of a huge untapped renewable energy potential in oceans, seas but also in rivers and canals. However, the low efficiency is an important barrier to its commercialization. The aim of this study is to present the selection of a multi-element hydrofoil that can enhance the hydrokinetic turbine performance. Therefore, in order to examine the influence of the type of airfoil used, as multi-element hydrofoil, on the blade performance, several studies using JavaFoil software were performed. The result indicates that hydrofoil multi-element Eppler 420 can provide high efficiency of the turbine because it has a higher relationship between the lift and drag coefficients C Lmax /C D (47.77) compared to the Selig S1223 profile (39.59) and other hydrofoils studied. Furthermore, computational fluid dynamics (CFD) was used to obtain the hydrodynamic characteristics of the hydrofoil Eppler 420 with and without flap. The CFD simulations were carried out using ANSYs-Fluent software. It was observed that there is an increase in the lift coefficient by 69.46% and 471.39 % for the hydrofoil with flap and a chord length of 30%, and a chord length of 70%, respectively, under the analyzed conditions with respect to the hydrofoil without flap.

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Section: D Javafoil Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of a lift augmented hydrofoil for hydrokinetic turbines

Chica¹,

Aguilar²,

Rubio-Clemente³

2024

RE&PQJ

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“…(2) Passive control techniques that do not require auxiliary power or a control loop, such as slot [13], multi-element airfoil [14][15][16], leading-edge slat [1,17], Gurney flap [18][19][20], self-activated flaps [21], vortex generator [22][23][24], stall strips [25,26], and other airfoil configurations that can delay or even eliminate dynamic stall.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling of Horizontal Axis Wind Turbine: Aerodynamic Performances Improvement Using an Efficient Passive Flow Control System

et al. 2022

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In this paper, we explore the improvement of the aerodynamic characteristics of wind turbine blades under stall conditions using passive flow control with slots. The National Renewable Energy Laboratory (NREL) Phase II rotor, for which detailed simulations and experimental data are available, served as a baseline for assessing the flow control system effects. The position and configuration of the slot used as a flow control system were determined using CFD analysis. The 3D-RANS equations are solved with ANSYS FLUENT using the k-ω SST turbulence closure model. The pressure coefficient for different wind speeds for the baseline configuration is compared to the available experimental data. The comparison shows that CFD results were better for the attached flow. The current work consists of a 3-D CFD modeling of a rotating blade equipped with different flow control systems: single-slot (S-S) and two-slots (T-S). The computation provides a better understanding of the influence of these flow control devices on the performance of wind turbine blades, the control of boundary layer separation, and the rotation effect. These control systems increase the power output by over 60% at high wind speeds with large separated boundary layer regions. For the configuration with the control system, the slot has shown its ability to delay the boundary layer separation. However, the improved aerodynamic performance has been proven for medium and high angles of attack where the flow is generally in the stall condition. The addition of the second slot changed the flow behavior, and an improvement was observed compared to the single slot configuration. The results are helpful for the design and development of a new generation of wind turbine blades.

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“…Horizontal-axis turbines are generally utilized for wind turbines, focusing on the use of multi-element airfoils to eliminate the losses of performance due to the requirement of thick airfoils in the inboard section of a wind turbine blade to resist structural, aerodynamic, and gravity loads resulting from the operation of the turbine [4]. Indeed, results reported by Ishaan Sood [5] demonstrated the capability of a turbine with multi-element blades to produce higher maximum power coefficient (C Pmax ) than a wind turbine with a traditional airfoil under equal operational conditions; for the same nominal power, the multi-element blade was proved to have higher efficiency and, thus, higher performance than that achieved with a traditional hydrofoil.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, the designed multi-element blade achieved the nominal power with a smaller blade radius, leading to material and manufacturing cost savings. The multi-element airfoil designed by Ragheb and Selig [4] offers an increase in the relationship between the lift and drag coefficients (C L /C D ) when compared to those included in the Delft University family of wind turbine airfoils [6,7] for C L values ≤ 1.7.…”

Section: Introductionmentioning

confidence: 99%

Design and Optimization of a Multi-Element Hydrofoil for a Horizontal-Axis Hydrokinetic Turbine

et al. 2019

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Hydrokinetic turbines are devices that harness the power from moving water of rivers, canals, and artificial currents without the construction of a dam. The design optimization of the rotor is the most important stage to maximize the power production. The rotor is designed to convert the kinetic energy of the water current into mechanical rotation energy, which is subsequently converted into electrical energy by an electric generator. The rotor blades are critical components that have a large impact on the performance of the turbine. These elements are designed from traditional hydrodynamic profiles (hydrofoils), to directly interact with the water current. Operational effectiveness of the hydrokinetic turbines depends on their performance, which is measured by using the ratio between the lift coefficient (CL) and the drag coefficient (CD) of the selected hydrofoil. High lift forces at low flow rates are required in the design of the blades; therefore, the use of multi-element hydrofoils is commonly regarded as an adequate solution to achieve this goal. In this study, 2D CFD simulations and multi-objective optimization methodology based on surrogate modelling were conducted to design an appropriate multi-element hydrofoil to be used in a horizontal-axis hydrokinetic turbine. The Eppler 420 hydrofoil was utilized for the design of the multi-element hydrofoil composed of a main element and a flap. The multi-element design selected as the optimal one had a gap of 2.825% of the chord length (C1), an overlap of 8.52 %C1, a flap deflection angle (δ) of 19.765°, a flap chord length (C2) of 42.471 %C1, and an angle of attack (α) of –4°.

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Multielement Airfoils for Wind Turbines

Cited by 4 publications

References 24 publications

Analysis of a lift augmented hydrofoil for hydrokinetic turbines

Analysis of a lift augmented hydrofoil for hydrokinetic turbines

Numerical Modeling of Horizontal Axis Wind Turbine: Aerodynamic Performances Improvement Using an Efficient Passive Flow Control System

Design and Optimization of a Multi-Element Hydrofoil for a Horizontal-Axis Hydrokinetic Turbine

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