Synthetic Jets as a Boundary Vorticity Flux Control Tool

Yen, Joshua; Ahmed, Noor A.

doi:10.2514/1.j051797

Cited by 20 publications

(5 citation statements)

References 29 publications

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“…Cubic splines were fitted to instantaneous pressure data [6,27] and BVF calculated direction from pressure gradient as given by Eqn. 3. Unsteady Reynolds-Averaged Navier-Stokes equations were solved using ANSYS CFX as described in [8,26]. The k-ω Shear Stress Transport turbulence model has been found to best simulate dynamic stall [10,23,29] as well as synthetic jet actuation in crossflows [30], and was consequently employed in this study.…”

Section: Methodsmentioning

confidence: 99%

“…As mentioned previously, the generalized theory of vorticity creation [2] provides the relationship to indirectly compute local BVF [26] from tangential surface acceleration, body forces, pressure gradients and three-dimensional viscous effects:…”

Section: Theory Of Vorticity Creationmentioning

confidence: 99%

“…Although these studies have found synthetic jets to positively improve dynamic stall, the effect of synthetic jets on vorticity creation has only been investigated on a stationary flat plate [26] and remains unexplored on oscillating airfoils experiencing dynamic stall. In light of the importance of vorticity in dynamic stall, the effect of synthetic jets on BVF is pertinent to DSV formation, or its suppression.…”

Section: Introductionmentioning

confidence: 98%

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Role of Synthetic Jet Frequency & Orientation in Dynamic Stall Vorticity Creation

Yen

Ahmed

2013

31st AIAA Applied Aerodynamics Conference

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Vorticity creation and its evolution play an important role in the formation of large dynamic stall vortices which cause large excursions in lift, drag and pitching moment on rapidly pitching and oscillating airfoils. While synthetic jets have shown potential in controlling dynamic stall vortices by sustaining lift increases without corresponding drag and pitching moment, their effect on the vorticity creation remains unknown. To address this, high fidelity computational fluid dynamics simulations were conducted to investigate how synthetic jet frequency and orientation alter the dynamic stall leading-edge boundary vorticity flux. Changes in baseline boundary vorticity flux were related to corresponding flow fields to delineate the role of synthetic jets in vorticity creation. Slot orientation was found to play a greater role in altering the amount of vorticity diffused into the flow than actuation frequency. Dynamic stall vortex sizes were found to be directly proportional to the vorticity diffused from the leading-edge and could therefore be effectively manipulated using synthetic jets. The study provides a better understanding of the dynamic stall vorticity creation process and its control using synthetic jets. Nomenclature ‫ܣ‬= synthetic jet amplitude, ‫ݏ݉‬ ିଵ = acceleration ‫ܥ‬ ఓ = synthetic jet momentum coefficient, ሺ݀ ܿ ⁄ ሻ൫ܷ ,௫ ܷ ஶ ⁄ ൯ ଶ ܿ = chord length ݀ = slot width = body force ݂ = airfoil oscillation frequency, ‫ݖܪ‬ ݂ = jet actuation frequency, ‫ݖܪ‬ ݂ ା = non-dimensional actuation frequency, ݂ ‫ݔ‬ ்ா ܷ ஶ ⁄ = unit normal vector pointing out of the flow ܲ = pressure ܴ݁ = chord Reynolds Number, ߩܷ ஶ ܿ ߤ ⁄ ‫ݏ‬ = distance along surface ‫ݐ‬ = time ܷ ,௫ = maximum jet velocity during blowing phase, ‫ݏ݉‬ ିଵ ܷ ஶ = freestream velocity ‫ݔ‬ ்ா = distance from synthetic jet to trailing-edge ߛ = slot orientation ߢ = reduced airfoil oscillation frequency, ߱ܿ 2ܷ ஶ ⁄ ߤ = dynamic viscosity ߩ = density = boundary vorticity flux, ‫ݏ݉‬ ିଶ ࣓ = vorticity ߱ = airfoil angular frequency, 2ߨ݂ ߱ = jet angular frequency, 2ߨ݂

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Section: Methodsmentioning

confidence: 99%

Section: Theory Of Vorticity Creationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Role of Synthetic Jet Frequency & Orientation in Dynamic Stall Vorticity Creation

Yen

Ahmed

2013

31st AIAA Applied Aerodynamics Conference

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“…As mentioned in section 1, space limitation prevented the fitting of a controlled rapid expansion and the achievement of the optimum contraction ratio of 12 to 16:1. When it is possible to fit such an arrangement, a variety of flow stabilization methods of varying suitability are available for wide angle diffusers [86][87][88][89][90][91][92][93][94].…”

Section: Diffuser Designmentioning

confidence: 99%

Wind Tunnel Designs and Their Diverse Engineering Applications

Ahmed¹

2013

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and as Manager of Low Speed Compressor Test Facility, UK the largest such industrial research facility in Europe. He is involved with Aerodynamics research with a bias towards environmentally friendly outcomes. He has developed novel flow control techniques, advanced flow diagnostic techniques, designed several wind tunnels and prize winning commercial fluid mechanical products of international acclaim. He has published well over 150 journal and conference papers and is regularly invited to give plenary/keynote lectures at different international conferences. Contents Preface XI Section Wind Tunnel Design 1

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“…Improving gearbox reliability is therefore a key performance goal for turbine manufactures and operators [11]. The aerodynamic research team of the University of New South Wales which has been heavily involved in the renewable energy studies [12][13][14], developing various passive [15][16][17][18][19][20][21][22][23][24] passive [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] flow control methodologies and diagnostics tools [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] started exploring new concepts to improve the fault diagnosti...…”

Section: Introductionmentioning

confidence: 99%

Design and Manufacture of a Planetary Gearbox Rig

Bligh

Ahmed

Zheng

2013

AMM

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Planetary gearboxes are required in many applications but have a high failure rate especially in wind turbines where rapid growth in turbine size is placing larger demands on the gearboxes. Current condition monitoring techniques are less effective at detecting faults in planetary gearboxes due to the complexity of the internal rotating components. A small scale planetary gearbox was, therefore, needed for testing on a gearbox test rig to develop a more effective method of condition monitoring. The detailed computer design and manufacture of the planetary gearbox for this purpose is detailed in this paper.

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Synthetic Jets as a Boundary Vorticity Flux Control Tool

Cited by 20 publications

References 29 publications

Role of Synthetic Jet Frequency & Orientation in Dynamic Stall Vorticity Creation

Role of Synthetic Jet Frequency & Orientation in Dynamic Stall Vorticity Creation

Wind Tunnel Designs and Their Diverse Engineering Applications

Design and Manufacture of a Planetary Gearbox Rig

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