Study on Riblet Drag Reduction Considering the Effect of Sweep Angle

Zhang, Yufei; Yin, Yajun

doi:10.3390/en12173386

Cited by 15 publications

(6 citation statements)

References 28 publications

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“…The effect of crossflows on the ribbed surfaces has been investigated in a number of studies [26,53,70,74,131]. Supercritical airfoils and swept wings are commonly employed in commercial aircraft to enhance stability and enable high-speed flights.…”

Section: Crossflows and Riblet Surfacesmentioning

confidence: 99%

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Advances in Riblets Design

Pakatchian,

Rocha,

2023

Applied Sciences

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Continuous evolution in nature has created optimum solutions for creature survival that have inspired many innovative engineering designs. Riblet geometries, passive flow control devices, have been studied, which were inspired by the skin of fast-swimming sharks. Turbulent boundary layer research reveals the positive effect of riblets in reducing drag by manipulating turbulent structures. Reducing drag is an important topic for the aviation industry, as it directly relates to fuel savings and reductions in carbon footprints. Aircraft noise represents another significant area of concern. When riblet designs modify turbulent structures, they can also impact pressure sources within the boundary layer, consequently influencing the generation of self-noise. Earlier research studies have demonstrated the favorable outcomes of riblet configurations on the variations in wall pressure, resulting in reduced levels of noise propagation. The current review paper is mainly devoted to the application of riblets in the aviation industry, focusing on studies that are performed in wind tunnels, flight tests, and using numerical techniques. Proving the desired performance of micro-grooves, their method of fabrication and implementation on aircraft surfaces are important topics that are also discussed. In addition, the effect of durability on the performance and required maintenance intervals was previously investigated and is also presented. Finally, recommendations for future activities in the relevant fields of study are provided.

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Section: Crossflows and Riblet Surfacesmentioning

confidence: 99%

“…The optimum design of riblet geometries, in terms of direction, configuration, height and spacing, should consider the flow behavior over the solid surfaces. Infinite wings were investigated by considering the effect of yaw angle [53,131]. Sundaram et al [53] carried out experimental studies with a 25 • yaw angle.…”

Section: Crossflows and Riblet Surfacesmentioning

confidence: 99%

Advances in Riblets Design

Pakatchian,

Rocha,

2023

Applied Sciences

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“…The drag increased when the yaw angle was 20 • or higher (Hirschel et al 1989, Enyutin et al 1991. A study using numerical simulations of blade riblets in channel flow also reported that the total drag with a yaw angle of 30 • was larger than that without riblets, where the friction drag decreased but the pressure drag increased (Zhang and Yin 2019).…”

Section: Introductionmentioning

confidence: 96%

Fluid drag reduction by penguin-mimetic laser-ablated riblets with yaw angles

2022

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The bodies of penguins, which swim underwater to forage, are densely covered with feathers, in which the barbs are oriented in the longitudinal direction. We hypothesize that these barbs act as riblets and reduce friction drag during swimming. Considering various real-world swim conditions, the drag reduction effect is expected to be robust against changes in the flow speed and yaw angle relative to the flow. To test this hypothesis, we created trapezoidal riblets based on the morphology of these barbs and measured the drag of flat plates with these fabricated riblets in a water tunnel. The spacing, width, and height of the barbs were found to be approximately 100, 60, and 30 μm, respectively. This spacing resulted in a nondimensional spacing s+ of 5.5 for a typical penguin swimming speed of 1.4 m/s. We fabricated four types of riblets on polyimide films by UV laser ablation. The first was a small-scale riblet for which the spacing was decreased to 41 μm to simulate the surface flow condition of the usual and slower swim behaviors in our water tunnel. The other three were manufactured to the actual scale of real barbs (spacing of 100 μm) with three different rib ridge widths: 10, 25, and 50 μm. Yaw angles of 0°, 15°, 30°, and 45° were also tested with the actual-scale riblets. The drag reduction rate of the small-scale riblet was maximized to 1.97% by the smallest s+ of 1.59. For all three actual-scale riblets, increasing the yaw angle from zero to 15° enhanced the drag reduction rate for the full range of s+ up to 13.5. The narrow-ridge riblet reduced drag at an even higher yaw angle of 45°, but the drag increased with zero yaw angle. Overall, the medium-ridge riblet, which was representative of the barbs, was well-balanced.

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“…Studies have shown that the drag reduction ability of Blade surfaces is sensitive to the yaw angle, which is the angle between the design direction of the riblet surface and the average flow direction. ,, The average flow direction rarely aligns with the designed direction of a riblet surface in various practical applications, such as side wind, vehicle steering, and swept wing aircraft while climbing . Studies have shown that the drag reduction ability of Blade surfaces decreases sharply as the yaw angle increases. ,,, When the flow direction is deflected, the interactions between structural surfaces and wall-bounded turbulence are subject to the combined effects of streamwise and spanwise directions rather than the effects of a single direction . Considering the spanwise influences of near-wall flow fields, previous studies have investigated Wavy, Sinusoidal, and Herringbone surfaces, which were designed to be parallel to the average flow direction.…”

Section: Introductionmentioning

confidence: 99%

“…22 Studies have shown that the drag reduction ability of Blade surfaces decreases sharply as the yaw angle increases. 18,20,21,23 When the flow direction is deflected, the interactions between structural surfaces and wallbounded turbulence are subject to the combined effects of streamwise and spanwise directions rather than the effects of a single direction. 24 Considering the spanwise influences of nearwall flow fields, previous studies have investigated Wavy, Sinusoidal, and Herringbone surfaces, which were designed to be parallel to the average flow direction.…”

Section: Introductionmentioning

confidence: 99%

Effects of the Yaw Angle on Air Drag Reduction for Various Riblet Surfaces

Zhou

Yan

et al. 2022

Langmuir

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Biomimetic riblet surfaces, such as blade, wavy, sinusoidal, and herringbone riblet surfaces, have widespread applications for drag reduction in the energy, transportation, and biomedicine industries. The drag reduction ability of a blade riblet surface is sensitive to the yaw angle, which is the angle between the design direction of the riblet surface and the average flow direction. In practical applications, the average flow direction is often misaligned with the design direction of riblet surfaces with different morphologies and arrangements. However, previous studies have not reported on the drag reduction characteristics and regularities related to the yaw angle for surfaces with complex riblet microstructures. For the first time, we systematically investigated the aerodynamic drag reduction characteristics of blade, wavy, sinusoidal, and herringbone riblet surfaces affected by different yaw angles. A precisely adjustable yaw angle measurement method was proposed based on a closed air channel. Our results revealed the aerodynamic behavior regularities of various riblet surfaces as affected by yaw angles and Reynolds numbers. Riblet surfaces with optimal air drag reduction were obtained in yaw angles ranging from 0 to 60°and Reynolds numbers ranging from 4000 to 7000. To evaluate the effects of the yaw angle, we proposed a criterion based on the actual spanwise spacing (d + ) of microstructure surfaces with the same phase in a near-wall airflow field. Finally, we established conceptual models of aerodynamic behaviors for different riblet surfaces in response to changes in the airflow direction. Our research lays a foundation for practical various riblet surface applications influenced by yaw angles to reduce air drag.

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Study on Riblet Drag Reduction Considering the Effect of Sweep Angle

Cited by 15 publications

References 28 publications

Advances in Riblets Design

Advances in Riblets Design

Fluid drag reduction by penguin-mimetic laser-ablated riblets with yaw angles

Effects of the Yaw Angle on Air Drag Reduction for Various Riblet Surfaces

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