Study of the Drag Reduction Characteristics of Circular Cylinder with Dimpled Surface

Yan, Fei; Yang, Haifeng; Wang, Lihui

doi:10.3390/w13020197

Cited by 15 publications

(12 citation statements)

References 28 publications

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“…But for the surface smoothed cylinder, the maximum C fθ was at about α = 50°. 6,22 As shown in Figure 17, the presence of the grooves caused C fθ to decrease for the location of α < 80°. As a results, the skin friction drag was lower than that of the surface smoothed cylinder, since the skin friction drag is obtained by integrating.…”

Section: Numerical Results and Discussionmentioning

confidence: 87%

“…5 These can both delay the flow separation and result in a smaller wake region, causing a lower drag than the smooth cylinders. [6][7][8] The results of wind tunnel tests have shown that such a conductor performs a lower drag by 32% compared with the conventional conductor at Re = 10 5 in the typhoon condition. 2 There has been an equivalent reduction in drag in field trials.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical investigation of flow over spiral grooved cylinders

Jun

Cheng

Liu

et al. 2022

Advances in Mechanical Engineering

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This study experimentally and numerically investigates the performance of a circular cylinder with a spiral grooved surface in terms of reducing wind drag. Its application in the overhead high-power conductor plays a vital role, especially in typhoon conditions. Wind tunnel tests have shown that at the critical Reynolds number (Re), the coefficients of wind drag decrease to a greater extent in a spiral grooved cylinder than in a smooth circular one. Moreover, a cylinder with a shallow groove and a small number of spirals could reduce the coefficient of drag in typhoon conditions. To gain an insight into the underlying fluid mechanism, a large-eddy simulation of turbulent flow from a critical to a super-critical Re has been carried out to approximate the flow separation and turbulent eddies over the spiral grooved cylinder. The results of the wind tunnel test have been used as a benchmark for the numerical results. The flow characteristics have been established about the near-wall flow separation and far wake flow, the pressure coefficient, the skin-friction coefficient, drag coefficient, and Q-criterion field.

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Section: Numerical Results and Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of flow over spiral grooved cylinders

Jun

Cheng

Liu

et al. 2022

Advances in Mechanical Engineering

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“…So, the conclusion can be drawn that when the dimpled distance is set reasonably, the recirculation zone of the circular cylinders with the dimpled surface is larger than that of the smooth cylinder, which means that the structure and number of dimple interfere with the wake vortex. Therefore, the formation of the larger vortex leads to a decrease in the vortex shedding frequency, thus the drag is reduced [27]. Furthermore, a close inspection revealed that b of case 2, case 3, and case 4 was slightly larger than that of case 1, which might be due to an increase in the separation angle [28,29].…”

Section: The Velocity Profiles and Recirculation Zonesmentioning

confidence: 94%

Dynamic Analysis of Wake Characteristics of the Circular Cylinder with a Dimpled Surface

Shao

Chen

et al. 2021

Water

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In order to understand the wake characteristics for the circular cylinder with the dimpled structure, particle image velocimetry (PIV) and proper orthogonal decomposition (POD) method are used to measure and analyze the flow field velocity and the flow characteristic of the wake flow of the circular cylinder with the dimpled surface. This study focuses on the distribution of Reynolds stress and turbulent kinetic energy, the velocity profiles and recirculation zones, and the velocity fluctuating characteristics of flow field with POD technology. It is found that the equivalent high-intensity Reynolds stress and turbulent kinetic energy regions of the circular cylinder with the dimpled surface are smaller, and the peak values are lower, and the velocity gradient in the wake region of the circular cylinder with the dimpled surface is larger. Otherwise, the energy contained by the dominant modes of the smooth cylinder is larger than that contained by the dominant modes of the circular cylinders with the dimpled surface, which means the energy of the dimpled cylinder is more distributed. At the same time, it is observed that the dimpled structure will decrease the vortex shedding intensity, but may increase the vortex shedding frequency, and destroy the inherent flow mode of the flow field around the cylinder.

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“…Moon, O'Connell and Glezer [17] also noted that studies conducted by other authors on dimples showed a lower pressure drop in comparison to other turbulators (such as continuous ribs) whilst significantly improving the thermal performance by a margin of 38%. Several other authors, including Abbas et al [18], Zhong et al [19] and Yan, Yang and Wang [20], have also conducted studies on the drag reduction properties of dimples on golf balls and cylinders, concluding that the addition of dimples has a significant effect on reducing the overall drag observed.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Pressure Drop Performance of Smooth and Dimpled Single Plate-Fin Heat Exchangers

Rauthan

Guzzomi

Vafadar

et al. 2021

Metals

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Passive heat exchangers (HXs) form an inseparable part of the manufacturing industry as they provide high-efficiency cooling at minimal overhead costs. Along with the aspects of high thermal cooling, it is essential to monitor pressure loss while using plate-fin HXs because pressure loss can introduce additional power costs to a system. In this paper, an experimental study was conducted to look at the effects of dimples on the pressure drop characteristics of single plate-fin heat exchangers. To enable this, different configurations of National Advisory Committee for Aeronautics (NACA) fins with smooth surfaces and 2 mm-diameter dimples, 4 mm-diameter dimples and 6 mm-diameter dimples were designed and 3D printed using fused deposition modelling (FDM) of ABS plastic. The depth to diameter ratio for these dimples was kept constant at 0.3 with varied diameters and depths. These were then tested using a subsonic wind tunnel comprised of inlet and outlet pressure taps as well as a hot wire velocimeter. Measurements were taken for pressure differences as well as average velocity. These were then used to calculate friction factor values and to compare the smooth fin to the dimpled fins in relation to their relative pressure drop performance. It was observed that for lower velocities the 4 mm dimples provided minimum pressure drop, with a difference of 58% when compared to smooth fins. At higher velocities, 6 mm dimples increased the pressure drop by approximately 34% when compared to smooth fins. It can also be concluded from the observed data in this study that shallower dimples produce lower pressure drops compared to deeper dimples when the depth to diameter ratio is kept constant. Accordingly, deeper dimples are more effective in providing drag reduction at lower velocities, whereas shallower dimples are more effective for drag reduction at higher velocities.

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Study of the Drag Reduction Characteristics of Circular Cylinder with Dimpled Surface

Cited by 15 publications

References 28 publications

Experimental and numerical investigation of flow over spiral grooved cylinders

Experimental and numerical investigation of flow over spiral grooved cylinders

Dynamic Analysis of Wake Characteristics of the Circular Cylinder with a Dimpled Surface

Experimental Investigation of Pressure Drop Performance of Smooth and Dimpled Single Plate-Fin Heat Exchangers

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