Experimental measurements of the drag force and the near-wake flow patterns of a longitudinally grooved cylinder

Zhou, Bo; Wang, Xikun; Guo, Wei‐yao; Zheng, Jiaxin; Tan, Soon Keat

doi:10.1016/j.jweia.2015.05.013

Cited by 40 publications

(9 citation statements)

References 25 publications

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“…The critical Reynolds number was found to decrease with increasing number of grooves. Zhou et al (2015) experimentally determined aerodynamic properties of the cylinders with 16 rectangular grooves in the Reynolds number range from 7,400 to 18,000. As in the case of other groove shapes, significant drag reduction was found together with the property of the grooved cylinder to mitigate vortex shedding.…”

Section: Recent Experiments Bymentioning

confidence: 99%

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Zhdanov

Busse

2019

European Journal of Mechanics - B/Fluids

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The aerodynamic coefficients and the Strouhal number of cylinders with three and four ribs, inspired by succulents Euphorbia trigona and Euphorbia Abyssinica are investigated using 2D Unsteady Reynolds-Averaged Navier-Stokes simulations at Reynolds number 20,000. Both configurations show a significant dependence of the studied characteristics on the angle of attack. The obtained results are compared to the smooth circular cylinder, previous results for cylinders with 24 ribs based on the Saguaro cactus, and cylinders with triangular and square cross-sections. Relative to the circular cylinder, the mean drag coefficient is lowered only for the four-rib case at high angles of attack. However, at some angular positions, the ability to reduce unsteady force fluctuations exceeds Saguaro-inspired cylinders. For both shapes studied, the Strouhal number at most angles of attack is lower compared to both the circular cylinder and cylinders with 24 ribs at the same Reynolds number. The minimum values of the aerodynamic coefficients for both configurations are related to the angular orientation. For the four-rib case a critical angle of α cr ≈ 40 • is observed, at which the mean drag coefficient and the fluctuating lift coefficient attain their minima. The mean lift coefficient reaches at this angle its maximum value before a sudden drop for higher angles of attack. Therefore, for cactus-shaped cylinders with four ribs high angles of attack give the optimum orientation relative to prevailing winds.

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Section: Recent Experiments Bymentioning

confidence: 99%

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Zhdanov

Busse

2019

European Journal of Mechanics - B/Fluids

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“…The axial/longitudinal corrugated surface has been found to increase the heat transfer by 15 − 30 % with a constant pumping power in the laminar flow [33,34] and turbulent airflow [35]. The axial/longitudinal and radial grooves also bring benefits to the heat pipe, the drag in pipe flow, reduction of aerodynamic noise, and the pressure difference between the projectile head and the concrete wall [36][37][38][39][40][41]. [42] examined a longitudinally grooved channel to enhance the diffusive transport on moderate Re and discovered the saturated flow that could intensify spanwise motions enhancing the advective transport.…”

Section: No /mentioning

confidence: 99%

Heat Transfer Enhancement and Friction in Double Pipe Heat Exchanger With Various Number of Longitudinal Grooves

Sunu¹,

Anakottapary²,

Suarta³

et al. 2020

Acta Polytech

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It has been found out that heat exchangers with longitudinal grooves produce better heat transfer than those without longitudinal grooves. However, up to now, there have been few investigations and applications of longitudinal grooves in relation to heat transfer associated with friction from the annulus of a heat exchanger. The present investigation examined the effects of longitudinal grooves in a double pipe heat exchanger on the characteristics of heat transfer and friction. Longitudinal rectangular grooves were carved into the outer side of a tube at a specified depth (t) and width (l). The effect of the number of longitudinal grooves, Reynolds number (Re), on the thermal and hydraulic performance was evaluated based on the heat exchanger experimental data. A total of four pipes were used: one pipe with 2 grooves, one pipe with 4 grooves, one pipe with 6 grooves and one pipe with 8 grooves. Water, hot and cold, was used as the working fluid. The test was performed with the cold water as the working fluid, with the Reynolds number from about 33 000 to 46 000 in a counter-flow scheme. The result showed that the number of grooves improved the heat transfer and caused a pressure drop. The increase in heat transfer ranged from 1.05 to 1.15, and the pressure loss of the system reached almost 30% as compared with the smooth annulus, the annulus with no groove. The installation of longitudinal grooves in a heat exchanger system enhanced the process of the heat flow through the boundary but provided a compensation for the pressure loss, which was correlated with the friction and pumping power.

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“…Zhou et al [1] investigated the flow around a smooth cylinder and a longitudinally grooved cylinder at Reynolds numbers ranging from 7.4×10 3 to 1.8×10 4 experimentally. This paper meant to found an improved understanding of effects of the grooved surface on the drag coefficient and the flow characteristics of cylinder.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation about Drag Force on the Both Icy and Non-icy Airfoils

Adibi¹

2019

I2M

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In this paper, the influence of icy boundary on the drag force is studied experimentally. For this purpose, at first, the drag force on NACA0015 airfoil is measured in a subsonic wind tunnel. The span of airfoil is 15 cm and its chord are 20 cm and the section of airfoil for experiments is 300×450 mm. Then, a cast is designed to produce icy airfoil with the same dimensions of aforementioned airfoil. The drag force of icy airfoil is measured in the same wind tunnel, too. Polyamid is used to make the cast. The results show that the drag force on the icy airfoil is up to 40 % less than non-icy one. This reduction is lower for smaller attack angles. Delayed boundary layer separation is the main reason for decrease in drag force. Sublimation of icy airfoil produces the secondary flow accompanying with a new boundary layer under the primary one. The secondary boundary layer is another reason for reduction of drag force. Experiments are conducted at different attack angles between and The Reynolds numbers are between 105 and 2.5×105. The accuracy of experimental instruments is considered and the results are obtained after numerical error analysis.

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Experimental measurements of the drag force and the near-wake flow patterns of a longitudinally grooved cylinder

Cited by 40 publications

References 25 publications

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Angle of attack dependence of flow past cactus-inspired cylinders with a low number of ribs

Heat Transfer Enhancement and Friction in Double Pipe Heat Exchanger With Various Number of Longitudinal Grooves

Experimental Investigation about Drag Force on the Both Icy and Non-icy Airfoils

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