Control of a boundary layer over a wind turbine blade using distributed passive roughness

Özkan, Musa; Erkan, Onur

doi:10.1016/j.renene.2021.11.082

Cited by 17 publications

(3 citation statements)

References 26 publications

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“…However, these methods are energy-intensive and require substantial maintenance. Conversely, passive control techniques, such as vortex generators, slots, riblets, and surface textures, offer a more cost-effective and simpler approach by manipulating pressure gradients through geometric modifications [13,14,15,16,17,18].…”

Section: Introductionmentioning

confidence: 99%

Enhancing Power Output of Ducted Wind Turbines through Flow Control

Akhter,

Shaaban,

Marini

2024

J. Phys.: Conf. Ser.

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This study focuses on the performance enhancement of a ducted small-scale National Renewable Energy Laboratory (NREL) Phase VI wind turbine, utilizing a Wind Lens diffuser. The investigation is conducted at the critical cut-in wind speed of 5 m/s. The research evaluates the integration of passive flow control devices, including Vortex Generators, Microtab, and Slot, strategically positioned across the Wind Lens to augment the mass flow through the rotor. The results indicate significant amplifications in the turbine output of up to 127%, attributable to airflow manipulation across the diffuser, resulting in increased torque and power output. The study highlights the effectiveness of employed flow control devices in managing turbulence and/or flow separation, thereby enhancing aerodynamics, particularly under low wind conditions. A comprehensive analysis of various parameters such as pressure and flow fields, turbulence, and other relevant metrics is conducted to ascertain their collective influence on rotor aerodynamics. The results demonstrate the potential of these passive flow control devices in advancing small-scale wind turbine technology, especially in regions with low wind potential. Moreover, the design simplicity and cost-effectiveness of these passive flow control devices suggest wider applicability in the renewable energy sector, contributing to the reduction of carbon-intensive energy reliance.

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Section: Introductionmentioning

confidence: 99%

Enhancing Power Output of Ducted Wind Turbines through Flow Control

Akhter,

Shaaban,

Marini

2024

J. Phys.: Conf. Ser.

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“…This study indicates that, under specific flow conditions, appropriate roughness can enhance the aerodynamic performance of wind turbine blade profiles within a Reynolds number range of 5 × 10 4 -1.5 × 10 5 . Moreover, roughness yields positive effects when the Reynolds number is less than 2.5 × 10 5 , and the roughness height (h) is equal to or less than 0.1 mm [80].…”

Section: Introductionmentioning

confidence: 99%

The effect of shortfin mako shark skin at the reattachment of a separated turbulent boundary layer

Santos,

Lang,

Wahidi

et al. 2024

Bioinspir. Biomim.

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This smooth flat experimental study investigates the capability of mako shark scales to control flow separation when placed downstream of the onset of turbulent boundary layer separation and within the reattachment region. The objective of the study is to validate the hypothesis that the shark scales’ bristling and recoiling would prevent the flow separation on the flank region (the fastest flow region) of the shark. A rotating cylinder was used to induce an adverse pressure gradient over a flat plate to produce a region of separated flow where the shark skin specimen was mounted. Two types of mako shark scales (flank (B2) and between flank and dorsal fin (B1)) were positioned in the preferred flow direction on a flat plate. The B2 scales are slender, 200 μm tall, and can bristle up to 50°. In contrast, B1 scales are wider, shorter, and can bristle at 30º. The bristling angle and shape are the main mechanisms by which the scales act to inhibit flow from moving upstream near the wall. Thus, the difference in the bristling angles and structures of the scales is attributed to the fact that the B2 scales function in a thicker boundary layer (behind the shark's gills) where they must bristle sufficiently high into the boundary layer to control the flow separation, and because the adverse pressure gradient in this region is higher where flow separation is more likely. The scales are placed in the reattachment region to elucidate their ability to control and reattach an already separated turbulent flow. The results show that B2 scales placed in the reattachment region reduce the size of the turbulent separation bubble and decrease the turbulent kinetic energy, while B1 scales have the opposite effect.

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“…These mechanisms can be broadly classified into active and passive control techniques. Passive techniques involve installation of microstructures, such as vortex generators [11], winglets [12], slats [13][14][15][16], riblets [17], surface texture/roughness [18], and slot/dimples/grooves [19], which manipulate pressure gradient across the blade surface to improve flow characteristics and aerodynamic performance. Active flow control mechanisms use a network of microsensors installed across the blade surface, which actively process sensor feedback to maintain or achieve optimal aerodynamic response through necessary local actuations [10,20].…”

Section: Introductionmentioning

confidence: 99%