Application and optimization of drag reduction characteristics on the flow around a partial grooved cylinder by using the response surface method

Xiaowen Song,Yuchen Qi,Mingxiao Zhang,Guogeng Zhang,Wenchao Zhan

doi:10.1080/19942060.2018.1562382

Xiaowen Song, Yuchen Qi + Show 3 more

Open Access

https://doi.org/10.1080/19942060.2018.1562382

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Abstract

ABSTRACTIt is well known that drag reduction occurs when the flow is passing by a grooved circular cylinder at certain Reynolds numbers, which has been used as a powerful energy saving method in a broad range of circumstances. However, a challenge here is how to evaluate the combined effects of depth, width and location of a given triangular groove set covering half of the cylindrical surface area. A useful approach to quantitatively analyze the influence of these different factors on drag reduction using the response surface methodology is described here. The flow characteristics, including drag coefficient, flow velocity, turbulent kinetic energy and vorticity, were calculated by numerical simulation. The results showed a great drag reduction effect under the legitimate set of groove structure parameters at a super-critical Reynolds number providing a base for optimization process in various engineering applications. The drag reduction mechanism found from this research could extend to other cases and should provide insights into engineering applications like car grilles.

Highlights

With the increase in energy consumption, there is a growing pressure to improve aerodynamic performance in order to achieve the energy saving for different applications, especially through reducing the drag force, a major component in energy consumption
The results showed a great drag reduction effect under the legitimate set of groove structure parameters at a super-critical Reynolds number providing a base for optimization process in various engineering applications
This is different from the mechanism of drag reduction when flow passes a plain surface with grooves, as the low-speed roller-bearing-like swirl is formed within the non-smooth unit, which translates sliding friction between the object surface and fluid into rolling friction, leading to skin friction reductions (Song, Lin, Liu, & Zhou, 2017; Song, Zhang, & Lin, 2017)

Summary

Introduction

With the increase in energy consumption, there is a growing pressure to improve aerodynamic performance in order to achieve the energy saving for different applications, especially through reducing the drag force, a major component in energy consumption. The non-smooth cover on the surface of the cylinder will reduce the coefficient of drag in great efficiency as it causes the critical regime at a lower Reynolds number (Rodriguez et al, 2017). This phenomenon has been verified by different experiments, which tested different non-smooth structures on the cylindrical surface of certain applications such as dimples (Bearman & Harvey, 1993; Tan, Koh, & Ng, 2016), grooves (Yamagishi, Kimura, & Oki, 2013; Yokoi, Igarashi, & Hirao, 2011). The same non-smooth surface with different designed parameters have been examined as an important aspect in drag reduction, for example, the influence of single

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