Flow Separation and Wake Behavior on Blunt Trailing-Edged Rotor Blades in Reverse Flow

Wild, Oliver; Jones, Anya R.

doi:10.2514/6.2023-2466

Cited by 2 publications

(3 citation statements)

References 4 publications

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“…The reduced frequency, k, is defined by k = ωc/(2U ∞ ). The relations between plunge displacement, h, plunge velocity, ḣ, and plunge acceleration, ḧ, are expressed in the following equation (12). For the current work, the two motion kinematics used in the current study are: a small-amplitude plunge with h m /c = 0.03 and a large-amplitude plunge with h m /c = 0.1.…”

Section: Methodsmentioning

confidence: 99%

“…These studies show that non-sharp trailing edges inevitably increase the profile drag, but can provide better lift performance through a more gradual adverse pressure gradient. In reverse flows seen in rotorcraft, blunt trailing edges can alleviate undesirable unsteady effects such as flow separation and vortex formation [11][12][13][14][15]. Additionally, airfoils with blunt or round trailing edges have better structural stiffness, which is desirable for applications such as wind turbines and compressor blades.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Rounded Trailing Edges on Unsteady Airfoil Loading at Low Reynolds Numbers

Lee,

Ramesh,

Gopalarathnam

2024

Preprint

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The steady potential flow past a traditional airfoil with a round leading edge and a sharp trailing edge can usually be simulated using the assumption of Kutta condition at the trailing edge. However, for the airfoil undergoing unsteady motion, especially at high reduced frequencies, numerical and experimental studies have shown that the flow can curve around the trailing edge, resulting in the stagnation point moving away from the trailing edge. This phenomenon becomes increasingly apparent when the airfoil has a round trailing edge instead of the usual sharp one. In this work, the effect of trailing edge roundness on the unsteady airfoil flow is studied by generating airfoil shapes with various amounts of roundness. Computational fluid dynamics (CFD) studies of unsteady flow past airfoils with different rounded trailing edges are performed to study the effects of the trailing-edge suction force on the flowfield. A composite pressure difference model universally valid on the entire airfoil is derived in this work to take into account the edge radii and the corresponding edge suction effect. We show that, in scenarios where the stagnation point moves away from the trailing edge, a trailing edge suction force associated with the flow curving around the trailing edge is necessary to better estimate the airfoil unsteady load distribution.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Rounded Trailing Edges on Unsteady Airfoil Loading at Low Reynolds Numbers

Lee,

Ramesh,

Gopalarathnam

2024

Preprint

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“…For instance, several studies have been carried out on how this opening (increase in thickness) of the TE affects the aerodynamic behavior of the isolated airfoil. The blunt TE airfoils (also called flatback airfoils) has been widely studied from different points of view [1,[4][5][6][7][8][9], both experimentally and computationally. In [10] the authors studied experimentally the effect of open TE on the aerodynamic characteristics of laminar airfoils at low Reynolds numbers, concluding that the increase of aerodynamic drag is larger than the one of lift, hence the airfoil efficiency decreases.…”

Section: Introductionmentioning

confidence: 99%

Computational investigation of the effect of the trailing edge thickness on the wind turbine performance

Echenique,

Puertolas,

Amo

2024

J. Phys.: Conf. Ser.

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Trailing edge (TE) thickness is a manufacturing constraint in blade design, especially for airfoils with a sharp TE. To achieve a specific TE thickness, blade geometry is often modified during the design process, typically in the outer zone of the blade where the airfoil’s TE is thinner. This area has a significant impact on energy production and loads. Quantifying the effect of TE thickness modifications is crucial for making informed design decisions. Therefore, this study quantifies and compares the impact of linear and polynomial geometry modifications on airfoil aerodynamics and turbine performance. Xfoil and OpenFAST were used to calculate these performance variations in the well-known NREL 5 MW wind turbine. The TE thickness of the model was modified to meet various manufacturing constraints, ranging from no restriction to a limit of 12mm TE thickness. In terms of the aerodynamic behavior of the airfoils, the maximum efficiency of airfoils with low relative thickness decreases as the TE thickness increases. Annual Energy Production shows a reduction of up to 0.42% for the worst case, while blade root loads increase by up to 20%. For low relative thickness airfoils, the linear method has proven to be a better option with less impact on performance.

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Flow Separation and Wake Behavior on Blunt Trailing-Edged Rotor Blades in Reverse Flow

Cited by 2 publications

References 4 publications

Effect of Rounded Trailing Edges on Unsteady Airfoil Loading at Low Reynolds Numbers

Effect of Rounded Trailing Edges on Unsteady Airfoil Loading at Low Reynolds Numbers

Computational investigation of the effect of the trailing edge thickness on the wind turbine performance

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