A Conceptual Study of Airfoil Performance Enhancements Using CFD

Ghoddoussi, Armin; Miller, L. Scott

doi:10.2514/6.2012-4655

Cited by 8 publications

(7 citation statements)

References 21 publications

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“…2. Jet position X + : By Review of slat position 12,13,14 and the previous work in this field 2,5,15 dimensionless distance of the oscillatory boundary condition from the leading edge X + = X jet /c, where X jet is the distance from the leading edge. The values of X + = 0.055, 0.0738, 0.09 and 0.2 are used.…”

Section: Numerical Formulationmentioning

confidence: 99%

Flow Control for NACA 4418Airfoil Using an “Active Slat”

Tawfik

Elhadidi

Abdelrahman

2015

53rd AIAA Aerospace Sciences Meeting

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In this study active flow control to delay separation over a NACA 4418 airfoil is investigated. The novel approach in this study is the use of an "Active Slat" in which the slat is opened and closed actively to enhance the mixing on the upper surface and delay separation. The concept of the active slat flow is realized by examining four different studies. First the simulation of a clean airfoil at Re=40,000 and angle of attack 10º is performed. Second an harmonic blowing jet is added on the upper surface of the airfoil. The width of the jet is 1.5% of chord length. Investigation for different jet parameters (dimensionless frequency f + , jet amplitude V jet , dimensionless distance X + , and relative exit flow angle) are examined to determine the best location for the slat opening, the reduced frequency for the active slat operation and the relative flow exit angle from the slat relative to the freestream. Simulation results show that an increase in lift up to 14% and reductionof drag of 47% is possible. Third the simulation of an airfoil with slat is investigated to determine the benefit of the slat alone with no active control. The slat increases the lift by 9% and reduced the drag by 18% and the separation is delayed. Finally an active slat is examined which basically is a fixed geometric slat with a "plug" that open and closes permitting the flow to pass through the slat intermittently with reduced frequency f + . This technique helps to enhance the flow mixing and is simpler to implement technically rather than a blowing controller. The results show that increase of the lift by 10% and decrease in drag by 37% which is slightly better than a slat only simulation. Examination of the benefit for different flow angles of attack will be investigated.Nomenclature α = angle of attack and defined otherwise µ = dynamic viscosity β = angle between free stream velocity and local jet surfacemomentum thickness f = frequency Δ = difference X = position h = height W = width p = Pressure L = lift D = drag V = velocity u,v = velocity components in x,y directions Subscripts and superscripts jet = blowing jet o = amplitude n = natural wake = characteristic at small angle of attack sep = separation bubble ∞ = free stream ˜ = average shear = characteristic at high angle of attack TE = trailing edge e = electrode d = dielectric + = non dimensional ⇀ = vector

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Section: Numerical Formulationmentioning

confidence: 99%

Flow Control for NACA 4418Airfoil Using an “Active Slat”

Tawfik

Elhadidi

Abdelrahman

2015

53rd AIAA Aerospace Sciences Meeting

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“…2. Jet position X + :By reviewing the slat position [6][7] [8] and based on the previous work [9][10] [11] dimensionless distance of the harmonic boundary condition based on leading edge point X + = X Jet /c, where X Jet is the distance measured from the leading edge. So, Jet is acting at X + =0.055, 0.074, 0.09 and 0.2.…”

Section: Control Parameters Selectionmentioning

confidence: 99%

Numerical investigation of helicopter hover state of flight enhancement by applying active flow control over helicopter special tip airfoil

Tawfik

Abdelrahman

Hassan

2022

J. Phys.: Conf. Ser.

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In conventional helicopter there are many operation limits and constraints, one of them is the maximum take-off weight and ability of main rotor to produce thrust during the hover mode of flight. In this study a numerical investigation is performed to show the effect of active flow control technique over the helicopter tip blade in hover mode to enhance the main rotor ability to produce lift by improving total performance of used airfoil. Active flow control applied to upper airfoil surface of blade tip close to the leading edge to control the boundary layer by adding momentum using small oscillating jet. The advantage of this technique comes from the small energy required to enrich the boundary layer which we use very small jet for excitation. Model is formed in 2D and is numerically investigated for airfoil used in main rotor blade tip with known geometry and performance parameter for clean rotor given by NASA test stand. Results shows very good impact on the hover mode in 2D model which gives enhancement in the overall performance represented by lift to drag ratio in the used tip airfoil in different case study used depending on the study plan that considered various excitation parameter. More than 60% increase in total performance represented by lift to drag ratio is obtained using suitable parameter and excitation point.

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“…The final parametric study was conducted to determine if the airfoil had an appreciable effect on the efficiency of the wind turbine. Armin Ghoddoussi [1] completed a conceptual study of performance enhancing devices for an airfoil is performed using computational fluid dynamics. The dimples demonstrate the potential of lift to drag ratio improvement at higher angle of attack and Bhadri Rajasai et al [7] is concerned with analysis of the turbulent flow over dimpled airfoil profiles.…”

Section: Introductionmentioning

confidence: 99%

Design and Analysis of Dimple Arrangement on a Small Wind Turbine Blade

Johny K*

2019

IJITEE

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This article predominantly focuses on the performance estimation of a small wind turbine blade when a dimple arrangement is made along its upper surface. The dimple arrangement is grooved at two locations: 0.25c and 0.5c, where c is the chord length of the turbine blade. A CFD analysis using the k-ε turbulence model is carried out on the selected blade sections NREL S823 and S822. The continuity and momentum equations are solved using ANSYS Fluent Solver to assess the aerodynamic performance of the proposed design. The effect of introducing a dimple on the blade surface has shown to delay the flow separation, with the formation of vortices. Further, the overall performance of the blade is simulated using GH BLADED and the results acquired are discussed.

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A Conceptual Study of Airfoil Performance Enhancements Using CFD

Cited by 8 publications

References 21 publications

Flow Control for NACA 4418Airfoil Using an “Active Slat”

Flow Control for NACA 4418Airfoil Using an “Active Slat”

Numerical investigation of helicopter hover state of flight enhancement by applying active flow control over helicopter special tip airfoil

Design and Analysis of Dimple Arrangement on a Small Wind Turbine Blade

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