Aerodynamics of permeable membrane wings. Part 2: Seepage drag

Iosilevskii, Gil

doi:10.1016/j.euromechflu.2012.11.004

Cited by 18 publications

(28 citation statements)

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“…Note that the obtained lift coefficient for a uniformly porous aerofoil with a parabolic camber line in (B 4) recovers eqn (42) in [18] as a → −1. [18]) is unaffected by the imposition of porosity at the leading edge.…”

Section: Appendix Asupporting

confidence: 73%

The steady aerodynamics of aerofoils with porosity gradients

Hajian¹,

Jaworski²

2017

Proc. R. Soc. A.

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This theoretical study determines the aerodynamic loads on an aerofoil with a prescribed porosity distribution in a steady incompressible flow. A Darcy porosity condition on the aerofoil surface furnishes a Fredholm integral equation for the pressure distribution, which is solved exactly and generally as a Riemann-Hilbert problem provided that the porosity distribution is Hölder-continuous. The Hölder condition includes as a subset any continuously differentiable porosity distributions that may be of practical interest. This formal restriction on the analysis is examined by a class of differentiable porosity distributions that approach a piecewise, discontinuous function in a certain parametric limit. The Hölder-continuous solution is verified in this limit against analytical results for partially porous aerofoils in the literature. Finally, a comparison made between the new theoretical predictions and experimental measurements of SD7003 aerofoils presented in the literature. Results from this analysis may be integrated into a theoretical framework to optimize turbulence noise suppression with minimal impact to aerodynamic performance.

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Section: Appendix Asupporting

confidence: 73%

The steady aerodynamics of aerofoils with porosity gradients

Hajian¹,

Jaworski²

2017

Proc. R. Soc. A.

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“…along

—see appendix A). There are two leading edges, and the force (per unit length) acting on each one of them is

where

is the coefficient with the square-root singularity of μ at the respective edge [ 14 ]. Its explicit form is

by (2.15) and (2.16).…”

Section: Fundamentalsmentioning

confidence: 99%

Hydrodynamics of a twisting slender swimmer

Iosilevskii

Rashkovsky

2020

R. Soc. open sci.

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Sea snakes propel themselves by lateral deformation waves moving backwards along their bodies faster than they swim. In contrast to typical anguilliform swimmers, however, their swimming is characterized by exaggerated torsional waves that lead the lateral ones. The effect of torsional waves on hydrodynamic forces generated by an anguilliform swimmer is the subject matter of this study. The forces, and the power needed to sustain them, are found analytically using the framework of the slender (elongated) body theory. It is shown that combinations of torsional waves and angle of attack can generate both thrust and lift, whereas combinations of torsional and lateral waves can generate lift of the same magnitude as thrust. Generation of lift comes at a price of increasing tail amplitude, but otherwise carries practically no energetic penalty.

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“…Hajian and Jaworski [15] have derived an expression for the non-dimensionalized steady static pressure difference between the suction and the pressure sides as a function of the chordwise location for porous airfoils. Their work is an extension to the expression derived by Iosilevskii [17,18], enabling the pressure distribution to be solved for any arbitrary porosity distribution specified as a differentiable function of the chordwise location [15]. The governing equations and main assumptions of Hajian and Jaworski are presented in this section.…”

Section: Thin-airfoil Methods For Predicting Steady Pressure Distrmentioning

confidence: 99%

“…by comparing the results to experimental or numerical results, has not yet been extensively investigated. Iosilevskii [17,18] has developed a closed-form expression to predict the aerodynamic parameters of a thin airfoil having a finite porous extent including the pressure distribution and the lift. The Darcy's law was applied to determine the possible flow velocity through the porous extent, based on the porous material's properties.…”

Section: Introductionmentioning

confidence: 99%