Pitch–Plunge Equivalence in Dynamic Stall of Ramp Motion Airfoils

Miotto, Renato F.; Wolf, William; Gaitonde, Datta V.; Visbal, Miguel R.

doi:10.2514/1.j061507

Cited by 7 publications

(1 citation statement)

References 46 publications

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“…The recent research effort to comprehend the aerodynamics of flapping wings is related to the development of micro-aerial vehicles and power extraction devices, in which thicker shapes generate higher thrust and propulsive efficiency for plunging airfoils [27]. Nevertheless, experimental data for plunging maneuvers are historically scarce, which leads to adapting well-known pitching results and methods for predicting flapping airfoil responses [28], where a fundamental concept is the airfoil's effective angle of attack [29].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear geometric decomposition of airfoils into the thickness and camber contributions

Torres,

Marques

2024

Meccanica

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In the thin airfoil theory, the camber line and the thickness distribution of general airfoils are mainly extracted by a linear combination of the upper and lower surfaces, giving rise to geometric distortions at the leading edge. Furthermore, despite the recent effort to obtain analytic expressions for the zero-lift angle of attack and quarter-chord moment coefficient, more analytic generalization is needed for the camber line component in the trigonometric series coefficients. This paper presents a straightforward algorithm to extract the camber line and thickness distribution of general airfoil shapes based on a finite differences method and the Bézier curve fitting. Integrals in the thin airfoil theory involving a Bernstein basis are performed, leading to series coefficients involving Gegenbauer polynomials. The algorithm is validated against analytical expressions of the NACA airfoils without introducing or adapting geometric parameters, and the results demonstrate good accuracy. In addition, the present work indicated a significantly different geometric behavior for the SD7003 airfoil camber slope at the leading edge obtained by the proposed algorithm and the classical linear approximation. Moreover, the method can be coupled conveniently in recent reduced-order models established on the thin airfoil theory to obtain expressions in closed forms for general airfoils.

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Section: Introductionmentioning

confidence: 99%

Nonlinear geometric decomposition of airfoils into the thickness and camber contributions

Torres,

Marques

2024

Meccanica

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Analysis of transient and intermittent flows using a multidimensional empirical mode decomposition

de Souza,

Miotto,

Wolf

2024

Theor. Comput. Fluid Dyn.

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Flow imaging as an alternative to non-intrusive measurements and surrogate models through vision transformers and convolutional neural networks

Miotto

Wolf

2023

Physics of Fluids

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A numerical framework is proposed whereby flow imaging data are leveraged to extract relevant information from flowfield visualizations. To this end, a vision transformer (ViT) model is developed to predict quantities of interest from images of unsteady flows. Here, the unsteady pressure distribution, the aerodynamic coefficients, and the skin friction coefficient are computed for an airfoil under dynamic stall as an example. The network is capable of identifying relevant flow features present in the images and associate them to the airfoil response. Results demonstrate that the model is effective in interpolating and extrapolating between flow regimes and for different airfoil motions, meaning that ViT-based models may offer a promising alternative for sensors in experimental campaigns and for building robust surrogate models of complex unsteady flows. In addition, we uniquely treat the image semantic segmentation as an image-to-image translation task that infers semantic labels of structures from the input images in a supervised way. Given an input image of the velocity field, a resulting convolutional neural network generates synthetic images of any corresponding fluid property of interest. In particular, we convert the velocity field data into pressure in order to subsequently estimate the pressure distribution over the airfoil in a robust manner. This approach proves to be effective in mapping between flowfield properties.

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Pitch–Plunge Equivalence in Dynamic Stall of Ramp Motion Airfoils

Cited by 7 publications

References 46 publications

Nonlinear geometric decomposition of airfoils into the thickness and camber contributions

Nonlinear geometric decomposition of airfoils into the thickness and camber contributions

Analysis of transient and intermittent flows using a multidimensional empirical mode decomposition

Flow imaging as an alternative to non-intrusive measurements and surrogate models through vision transformers and convolutional neural networks

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