Capture width of the three-float multi-mode multi-resonance broadband wave energy line absorber M4 from laboratory studies with irregular waves of different spectral shape and directional spread
Capture width of the three-float multi-mode multi-resonance broadband wave energy line absorber M4 from laboratory studies with irregular waves of different spectral shape and directional spread
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DOI：
10.1007/s40722-015-0022-6
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发表时间：
2015-04
影响因子：
1.9
通讯作者：
P. Stansby;E. C. Moreno;T. Stallard
中科院分区：
文献类型：
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作者：
P. Stansby;E. C. Moreno;T. Stallard
系泊多体线缆是近海波能转换的一种有吸引力的选择。实验室研究了三浮子系统M4在多模激励和垂荡共振情况下的俘获宽度，其中相邻浮子间距约为典型波长的一半，从而提供了反相位强迫。浮子的直径和吃水从船头到船尾增加，船头和中间的浮子由横梁刚性连接。在中间浮子上方带有阻尼器的铰链从船首/中间浮子和尾部浮子之间的相对旋转中吸收动力。每个浮子的共振垂荡频率是不同的。中浮体和尾浮体之间的反相涌浪强迫是很大的，而没有产生共振的静水刚度。这代表了一个流体力学复杂的系统，实验室实验表明，在一系列峰值周期内，不规则波的总捕获宽度很高，没有进行减振优化。在不同的光谱峰度和方向扩散下，捕获宽度大于波长的20%(基于能量周期)，跨越典型的海上浮标基地的典型峰值周期。最大捕获宽度约为圆形基座浮动波长的37%；通过减少阻力造成的能量损失，圆形基座而不是扁平基座使能量捕获增加了高达60%。对于平底浮标，与五倍大且等效阻尼值相近的几何定标装置相比，捕获宽度与波长比例相似。
A moored multi-body line absorber is an attractive option for offshore wave energy conversion. Laboratory studies have been undertaken to determine capture width with multi-mode excitation and heave resonance for the three-float system M4 where the adjacent float spacing is about half a typical wavelength giving anti-phase forcing. The floats increase in diameter and draft from bow to stern and the bow and mid float are rigidly connected by a beam. A hinge with a damper above the mid float absorbs power from the relative rotation between the bow/mid float and the stern float. The resonant heave frequency for each float is different. Anti-phase surge forcing between mid and stern floats is substantial, while there is no hydrostatic stiffness producing resonance. This represents a hydrodynamically complex system and the laboratory experiments indicate high overall capture widths in irregular waves across a range of peak periods without damping optimisation. With different spectral peakedness and directional spread, the capture width is greater than 20 % of a wavelength (based on the energy period) across a range of peak periods typical of an offshore site for floats with a rounded base. The maximum capture width was about 37 % of a wavelength with rounded base floats; having rounded rather than flat bases increased energy capture by up to 60 % by reducing energy losses due to drag. For floats with flat bases comparisons with a geometrically scaled device five times larger and with similar magnitudes of equivalent damping showed similar capture widths as a proportion of wavelength.