VIVs of a circular cylinder with a downstream strip-plate in cruciform arrangement

Kato, Naoto; Koide, Mizuyasu; Takahashi, Tsutomu; Shirakash, Masataka

doi:10.1016/j.jfluidstructs.2012.02.007

Cited by 17 publications

(7 citation statements)

References 29 publications

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“…Various geometries and orientations of downstream body are considered in the studies of flow-induced vibration by Zhou et al. (2005), Assi and Bearman (2009), Kato et al. (2012) and Kawabata et al.…”

Section: Introductionmentioning

confidence: 99%

Downstream flat plate as the flow-induced vibration enhancer for energy harvesting

Maruai

Ali

Ismail

et al. 2017

Journal of Vibration and Control

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The prospect of harvesting energy from flow-induced vibration using an elastic square cylinder with a detached flat plate is experimentally investigated. The feasibility of flow-induced vibration to supply an adequate base excitation for micro-scale electrical power generation is assessed through a series of wind tunnel tests. The current test model of a single square cylinder is verified through a comparable pattern of vibration amplitude response with previous experimental study and two-dimensional numerical simulations based on the unsteady Reynolds averaged Navier–Stokes (URANS). In addition, a downstream flat plate is included in the wake of the square cylinder to study the effects of wake interference upon flow-induced vibration. A downstream flat plate is introduced as the passive vibration control to enhance the magnitude of flow-induced vibration and simultaneously increases the prospect of harvesting energy from the airflow. The study is conducted by varying the gap separation between the square cylinder and flat plate for 0.1≤ G/ D ≤3. The highest peak amplitude is observed for the gap G/ D = 1.2 with yrms/ D = 0.46 at UR = 17, which is expected to harvest ten times more energy than the single square cylinder. The high amplitude vibration response is sustained within a relatively broader range of lock-in synchronization. Meanwhile, for G/ D = 2 the vibration is suppressed, which leads to a lower magnitude of harvested energy. Contrarily, the amplitude response pattern for G/ D = 3 is in agreement with the single square cylinder. Hence, the flat plate has no significance to the wake interference of the square cylinder when the gap separation is beyond 3 D.

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Section: Introductionmentioning

confidence: 99%

Downstream flat plate as the flow-induced vibration enhancer for energy harvesting

Maruai

Ali

Ismail

et al. 2017

Journal of Vibration and Control

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“…間量によって振動を制御する方法を検討した , 加藤他, 2007 ．十字交差配置した 2 つの柱状体の前方柱状体には主流方向に回転軸を持つ縦渦が形成されることでカルマン渦の形成が阻害されカルマン渦励振(Karman Vortex-Induced Vibration, KVIV)が抑制される (裴他, 1993) ．さらに，特定の条件下では縦渦の周期的流出に伴う渦励振，すなわち縦渦励振現象(Longitudinal Vortex-Induced Vibration, LVIV ) が発生することを見いだした (Kato et al, 2012, Koide et al, 2006 ．LVIV は KVIV よりも強い励振力を有する．そこで縦渦が誘起する強い揚力に注目し，縦渦の周期性を抑制し特定の位置に定常的に存在させる方法を見いだした．定在する縦渦が前方柱状体に作用する揚力を駆動力として一様流に対して直交方向の力を誘起し，これを回転力とする全く新しいコンセプトの円柱翼風車を報告した (Takahashi et al, , 高橋他, 2016 加藤直人, 小出瑞康, 高橋勉, 白樫正高, 円柱の下流に十字交差配置された帯状の平板による振動制御 (第1報, 固定系からの縦渦流出), 日本機械学会論文集B編, Vol. 73, No.…”

Section: 著者らのグループでは，振動する円筒後方に別の柱状物体を設置することで流れ場を変化させ，物体間のすきunclassified

Effect of blade tip on torque characteristics of circular cylinder blade wind turbine driven by longitudinal vortex

Nakada

Sato

Takahashi

2022

Transactions of the JSME (In Japanese)

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In a circular cylinder blade wind turbine driven by a longitudinal vortex, the torque characteristics of the turbine are greatly affected by the flow field at the blade tip. In general, wind turbines reduce drag by making the blade tips thinner. However, because this wind turbine uses a cylinder as a blade, it is important to control the flow field at the blade tip. From the experiments, it was found that the torque coefficient can be increased by attaching the endplate to the blade tips, and the rotational force can be obtained stably up to very low rotation speeds. The installation of fairing or endplates in circular cylinder blade wind turbines enables stable rotation at low speeds even under high loads, and also reduces drag at high speeds and increases the maximum speed. In the case of a disc-shaped endplate, the torque coefficient can be increased by up to 20% by attaching an endplate with a diameter 2.5 to 3 times the diameter of the cylinder to the outer blade tip only. The L-type endplate has the effect of shifting the characteristics to the higher rotation side than the disk type, and increases the torque coefficient at the same tip speed ratio. However, the lower limit of stable rotation becomes higher, and as a result, the value of the maximum torque coefficient obtained at high load decreases. If the endplate attached inside has a negative effect on the stable formation of the necklace vortex, it will inhibit the rotation at a low speed due to high load, making it difficult to obtain high torque.

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“…Vortex-induced vibration (VIV) of a circular cylinder has always been of interest to researchers due to its engineering applications (Jauvtis & Williamson 2003;Zhao et al 2009). In particular, if the self-oscillation frequency of a downstream structure is close to the vortex shedding frequency from the upstream circular cylinder, the structure will be destroyed by resonance (Deng et al 2007;Kato et al 2012;Nguyen et al 2012). Therefore, the relationship between wake morphologies and flow frequencies is worth studying.…”

Section: Introductionmentioning

confidence: 99%

“…Different arrangements of multiple circular cylinders also affect the morphologies of the wake vortices. For two circular cylinders, parallel (including tandem, side-by-side and staggered) and crossing arrangements make the flow past the cylinders more complex (Kato et al 2012;Nguyen et al 2012;Sumner 2010;Tong et al 2015;Zhao & Lu 2018;Zhou & Mahbub Alam 2016). For instance, if two circular cylinders are perpendicular to each other, i.e.…”

Section: Introductionmentioning

confidence: 99%

Spectral Analysis of Flow Around Single and Two Crossing Circular Cylinders Arranged at 60 and 90 Degrees

Wang¹,

Yang²,

Tang³

et al. 2022

Preprint

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Two modal decomposition techniques, including proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD), are used to identify the wake patterns past single and two crossing cylinders in 60° and 90° arrangements with gap ratio G = 4. The flow is simulated using direct numerical simulations (DNS) for Reynolds numbers Re = 100. The spatial scale of flow decreases with increasing modal frequency from the modal analysis. Two main modes are identified in the wake of the cylinders, namely spatially antisymmetric and symmetric modes. Antisymmetric and symmetric modes are related to cylinders’ vortex shedding and shedding vortices’ shift motion, respectively, whose frequencies are odd and even multiples of cylinders’ lift force frequency. In addition, a low-frequency mode concerning the shadowing effect of the downstream cylinder (DC) in 90° arrangement is found in the wake of the DC centre.

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VIVs of a circular cylinder with a downstream strip-plate in cruciform arrangement

Cited by 17 publications

References 29 publications

Downstream flat plate as the flow-induced vibration enhancer for energy harvesting

Downstream flat plate as the flow-induced vibration enhancer for energy harvesting

Effect of blade tip on torque characteristics of circular cylinder blade wind turbine driven by longitudinal vortex

Spectral Analysis of Flow Around Single and Two Crossing Circular Cylinders Arranged at 60 and 90 Degrees

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