Experimental Study on the Effects of Winglets on the Performance of Two Interacting Horizontal Axis Model Wind Turbines

Ostovan, Yaşar; Uzol, Oguz

doi:10.1088/1742-6596/753/2/022015

Cited by 12 publications

(8 citation statements)

References 5 publications

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“…In average, there is about 15% reduction in the estimated induced drag levels when the winglets are attached. This reduction in the induced drag is consistent with the increase in the power production (around 3-4%) observed in previously performed experiments on the same rotor around the design TSR of 6 [9] when winglets are used.…”

Section: Effects On Induced Dragsupporting

confidence: 90%

“…This point will be discussed in a more quantitative manner in the next section. Weakened tip vortices due to the presence of the winglets are also expected to cause an increase in power performance, which was indeed observed near design TSR in previous measurements obtained in the same experimental setup [9]. asmeJoSE_SOL-17-391-0…”

Section: Flow Field Characteristics Near the Tipsupporting

confidence: 60%

“…Shimizu et al [7] and Abdulrahim et al [8] has experimentally shown that Mie-vane type tip devices can also have positive effects on the power performance of wind turbines. Effects of winglets used in the current study on the power and thrust coefficients of the model wind turbine have been investigated asmeJoSE_SOL-17-391-0 Uzol 5 previously by the authors [9]. Results show that for the turbine running near design TSR of 6, power and thrust coefficients increase about 4.2% and 6.5%, respectively.…”

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confidence: 95%

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Experimental Investigation of the Effects of Winglets on the Tip Vortex Behavior of a Model Horizontal Axis Wind Turbine Using Particle Image Velocimetry

Ostovan

Akpolat

Uzol

2018

Journal of Solar Energy Engineering

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This study presents an experimental investigation on the effects of winglets on the near wake flow around the tip region and on the tip vortex characteristics downstream of a 0.94 m diameter three-bladed horizontal axis wind turbine (HAWT) rotor. Phase-locked 2D particle image velocimetry (PIV) measurements are performed with and without winglets covering 120 deg of azimuthal progression of the rotor. The impact of using winglets on the flow field near the wake boundary as well as on the tip vortex characteristics such as the vortex convection, vortex core size, and core expansion as well as the resultant induced drag on the rotor are investigated. Results show that winglets initially generate an asymmetric co-rotating vortex pair, which eventually merge together after about ten tip chords downstream to create a single but nonuniform vortex structure. Mutual induction of the initial double vortex structure causes a faster downstream convection and a radially outward motion of tip vortices compared to the baseline case. The wake boundary is shifted radially outward, velocity gradients are diffused, and vorticity and turbulent kinetic energy levels are significantly reduced across the wake boundary. The tip vortex core sizes are three times as big compared to those of the baseline case, and within the vortex core, vorticity and turbulent kinetic energy levels are reduced more than 50%. Results show consistency with various vortex core and expansion models albeit with adjusted model coefficients for the winglet case. The estimated induced drag reduction is about 15% when winglets are implemented.

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Section: Effects On Induced Dragsupporting

confidence: 90%

Section: Flow Field Characteristics Near the Tipsupporting

confidence: 60%

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confidence: 95%

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Experimental Investigation of the Effects of Winglets on the Tip Vortex Behavior of a Model Horizontal Axis Wind Turbine Using Particle Image Velocimetry

Ostovan

Akpolat

Uzol

2018

Journal of Solar Energy Engineering

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“…A smaller number of recent studies also focused on the wake flow behind a wind turbine with winglets, investigating which effect the tip extensions could have on a cluster of multiple turbines. A recent experiment by Ostovan and Uzol compared the performance of a two‐turbine array with and without winglets attached to the blade tips of the upstream turbine (

D

= 0.90 m). They measured an increase of about 2.5% in the upstream turbine's power production.…”

Section: Introductionmentioning

confidence: 99%

An experimental study on the effects of winglets on the tip vortex interaction in the near wake of a model wind turbine

et al. 2020

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An experimental study of the near wake up to four rotor diameters behind a model wind turbine rotor with two different wing tip configurations is performed. A straight-cut wing tip and a downstream-facing winglet shape are compared on the same two-bladed rotor operated at its design tip speed ratio. Phase-averaged measurements of the velocity vector are synchronized with the rotor position, visualizing the downstream location of tip vortex interaction for the two blade tip configurations. The mean streamwise velocity is found not to be strongly affected by the presence of winglet tip extensions, suggesting an insignificant effect of winglets on the time-averaged inflow conditions of a possible downstream wind turbine. An analysis of the phase-averaged vorticity, however, reveals a significantly earlier tip vortex interaction and breakup for the wingletted rotor. In contradistinction, the tip vortices formed behind the reference configuration are assessed to be more stable and start merging into larger turbulent structures significantly further downstream. These results indicate that an optimized winglet design can not only contribute to a higher energy extraction in a rotor's tip region but also can positively affect the wake's mean kinetic energy recovery by stimulating a faster tip vortex interaction. KEYWORDStip vortex, wake, wind energy, winglets 1 2.6%. Another study by Gaunaa and Johansen 7 showed a stronger positive effect on the power coefficient for downstream-facing winglets than

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“…Moreover, the effects of winglets on the performance of two interacting horizontal wind turbines have been investigated. It was proven that the overall power efficiency of two turbines increases when the upstream rotor blades are equipped with downwind winglets (Ostovan and Uzol, 2016). In parallel, computational fluid dynamics (CFD) research confirms the purposefulness of winglets.…”

Section: Introductionmentioning

confidence: 99%

Investigation of performance of small wind turbine blades with winglets

Kulak

Lipian

Zawadzki

2020

HFF

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Purpose This paper aims to discuss the results of the performance study of wind turbine blades equipped with winglets. An investigation focusses on small wind turbines (SWTs), where the winglets are recalled as one of the most promising concepts in terms of turbine efficiency increase. Design/methodology/approach To investigate a contribution of winglets to SWT aerodynamic efficiency, a wind tunnel experiment was performed at Lodz University of Technology. In parallel, computational fluid dynamics (CFD) simulations campaign was conducted with the ANSYS CFX software to investigate appearing flow structures in greater detail. Findings The research indicates the potential behind the application of winglets in low Reynolds flow conditions, while the CFD study enables the identification of crucial regions influencing the flow structure in the most significant degree. Research limitations/implications As the global effect on a whole rotor is a result of a small-scale geometrical feature, it is important to localise unveiled phenomena and the mechanisms behind their generation. Practical implications Even the slightest efficiency improvement in a distributed generation installation can promote such a solution amongst energy prosumers and increase their independence from limited natural resources. Originality/value The winglet-equipped blades of SWTs provide an opportunity to increase the device performance with relatively low cost and ease of implementation.

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Experimental Study on the Effects of Winglets on the Performance of Two Interacting Horizontal Axis Model Wind Turbines

Cited by 12 publications

References 5 publications

Experimental Investigation of the Effects of Winglets on the Tip Vortex Behavior of a Model Horizontal Axis Wind Turbine Using Particle Image Velocimetry

Experimental Investigation of the Effects of Winglets on the Tip Vortex Behavior of a Model Horizontal Axis Wind Turbine Using Particle Image Velocimetry

An experimental study on the effects of winglets on the tip vortex interaction in the near wake of a model wind turbine

Investigation of performance of small wind turbine blades with winglets

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