On hydrodynamic characteristics of gap resonance between two fixed bodies in close proximity

Gao, Junliang; Zang, Jun; Chen, Lifen; Chen, Qiang; Ding, Haoyu; Liu, Yingyi

doi:10.1016/j.oceaneng.2018.12.052

Cited by 79 publications

(30 citation statements)

References 22 publications

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“…Jiang et al [23] and Gao et al [26] found that the wave response in the gap decreased with the increasing of wave height, while the resonant frequency in the gap were nearly the same. When the wave resonances in the gap near ω=2.79 rad/s, the dissipation coefficient increases and the conversion efficiency decreases suddenly for the hybrid system with the triangular WEC, as shown in Fig.…”

Section: Effect Of Incident Wave Height Hi/hmentioning

confidence: 98%

“…The results revealed that large amount of vortices were generated by the sharp corners of the two barges and shed downward, and the viscous damping associated with the twin-barge system was demonstrated dependent on the incident wave steepness. Gao et al [26] used OpenFOAM software to investigate the resonant water motion inside a narrow gap between two identical fixed boxes those were in the side-by-side configuration, and the free-surface elevation in the narrow gap, wave loads on the bodies and the effects of the incident wave height on the reflection, transmission and energy loss coefficients were analyzed. It is not possible to infer the effect of wave resonance in the WEC-breakwater gap on the energy extraction performance of the dual-floater system from existing studies.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamic performance of a dual-floater hybrid system combining a floating breakwater and an oscillating-buoy type wave energy converter

et al. 2020

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The high power generation cost impedes commercial-scale wave power operations. The main objective of this work was to provide a cost-sharing solution through combing the wave extraction and costal protection performance. A two-dimensional numerical wave tank was developed using Star-CCM+ Computational Fluid Dynamics software to investigate the hydrodynamic performance of a dual floater hybrid system consisting of a floating breakwater and an oscillating-buoy type wave energy converter (WEC). The new model was verified with published experimental results. The differences between the hydrodynamic performance of the hybrid system, a single WEC and a single breakwater were compared. The effects of the wave resonance in the WEC-breakwater gap and the geometrical parameters on the performance of the asymmetric WEC were also studied. It was found that the hybrid system demonstrated both better wave attenuation and wave energy extraction capabilities at low wave frequencies, i.e., wider effective frequency. The forces on the breakwater were generally reduced due to the WEC. Wave resonance in the narrow gap has an adverse effect on the hybrid system with an asymmetric WEC, while a beneficial effect with a symmetric WEC. The wave energy conversion efficiency of hybrid system can be improved by increasing the draft and width of the WEC and decreasing the distance between the WEC and the breakwater. The findings of this paper make wave energy economically competitive and commercial-scale wave power operations possible.

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Section: Effect Of Incident Wave Height Hi/hmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Hydrodynamic performance of a dual-floater hybrid system combining a floating breakwater and an oscillating-buoy type wave energy converter

et al. 2020

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“…7–9 In other words, under the action of wave breaking, bow wave and jet, bubbles were formed in water. 10–12 Studies showed that the bow wave drew air into the water, which caused the formation of bubbles. Bubbles flowed backward along the ship bottom.…”

Section: Introductionmentioning

confidence: 99%

Reducing bubble generation and sweepdown effect on a research vessel with a moonpool

Yao

Huang

Shi

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part M:

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Some research vessels set moonpools for sonars installation. The moonpool provides a relatively good working environment for sonar in a harsh marine environment. At the same time, other acoustic detection equipment are installed along the ship bottom behind the moonpool. Due to the exist of the sonar with a variable cross-section, the number of bubbles generated in the moonpool increases. The bubbles generated in the moonpool expel and flow along the vessel bottom to the stern, which leads to the sweepdown effect. The performance of the sonar and other acoustic detection equipment degrades by the bubbles around. However, the research on reducing bubble generation in the moonpool and sweepdown effects is rare. So in present paper the reduction effects of damping devices such as the flange and choke deck on the bubble generation in the moonpool are investigated experimentally. Then, in order to reduce the sweepdown effects of bubbles on the ship bottom, three other damping devices which are double flaps, diversion channel and wedge are investigated. It can be seen that through reducing the area of bubble leakage in the moonpool the distribution position of bubbles can be effectively restricted and the width and thickness of the bubbles reduce.

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“…Most objects of the research studies on the shear layer oscillation were aerodynamic cavity instead of the moonpool [19][20][21][22][23]. e shear oscillation was studied by visual methods such as laser Doppler velocity measurement (LDA) and particle image velocimetry (PIV) [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Research on Oscillating Characteristics of the Shear Layer on the Ship Bottom with a Moonpool under the Action of the Current and Wave

Huang

Yao

Shi

et al. 2021

Mathematical Problems in Engineering

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For some research vessels, a sonar is installed in the moonpool, and some acoustic detection equipment are installed on the ship bottom behind the moonpool, which helps to avoid the impact of the high-speed flow. The moonpool causes the ship bottom discontinued, forming a particular shear layer oscillation. The shear layer oscillation affects the bubble generation and motion in and behind the moonpool. The sonar and acoustic equipment will malfunction when surrounded by many bubbles. However, there is almost no research on the shear layer oscillation near the moonpool. So, in this paper, by measuring the pressure near the moonpool and monitoring the fluid motion in the moonpool and bubbles’ distribution along the ship bottom, the shear layer oscillation near the moonpool is studied experimentally under the action of the incident current and wave. Furthermore, the effects of the sonar and the moonpool shape are investigated. It can be seen that the shear layer oscillation excites the fluid motion in the moonpool. The sonar forms a complicated boundary in the moonpool, resulting in the increase in the frequency of the shear layer oscillation. The shear layer propagates along the ship bottom in the form of the ship bottom wave. Clarifying the oscillating characteristics of the shear layer along the ship bottom with a moonpool is conducive to the design of moonpools in the research ships, and the detection instruments are arranged in the right place along the ship bottom, so as to make sure the detection instruments work properly and detect the marine environment more accurately.

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On hydrodynamic characteristics of gap resonance between two fixed bodies in close proximity

Cited by 79 publications

References 22 publications

Hydrodynamic performance of a dual-floater hybrid system combining a floating breakwater and an oscillating-buoy type wave energy converter

Hydrodynamic performance of a dual-floater hybrid system combining a floating breakwater and an oscillating-buoy type wave energy converter

Reducing bubble generation and sweepdown effect on a research vessel with a moonpool

Research on Oscillating Characteristics of the Shear Layer on the Ship Bottom with a Moonpool under the Action of the Current and Wave

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