Experimental And Numerical Study of Spar Buoy-magnet/spring Oscillators Used As Wave Energy Absorbers
Experimental And Numerical Study of Spar Buoy-magnet/spring Oscillators Used As Wave Energy Absorbers
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柱状浮标-磁体/弹簧振荡器用作波浪能吸收器的实验和数值研究
DOI：
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发表时间：
2007
期刊：
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通讯作者：
J. Cheung
中科院分区：
文献类型：
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作者：
A. Grilli;J. Merrill;S. Grilli;M. Spaulding;J. Cheung
我们研究自由浮点吸收波发生器，它由一个或几个（主要是起伏的）翼梁浮标的组合组成，容纳至少一个短冲程线性发生器（SSLG），由磁铁制成，悬挂在弹簧上，并在线圈内振荡。该系统旨在为海洋沿海监视系统产生低功率和可再生波浪能（高达千瓦）。进行比例模型实验和数值建模是为了调整系统参数并最大化其对目标海况的响应（即在升沉和磁体运动中接近共振运行）。我们发现，对于此类浮标系统，粘性摩擦是共振附近的主要阻尼机制，因此，浮标的湿末端也必须适当流线型，并且滚动必须最小化，因为它可能会显着增加这种阻尼。这可以通过所谓的三柱式系统来实现，其中3个相同直径的柱式浮标以等边三角形配置安装，彼此间隔一个直径。由于翼梁浮标的升沉共振周期主要是其吃水的函数，为了降低该周期并更好地匹配 SSLG 的共振周期，Trispar 中每个浮标的吃水是不同的（在比例模型中为 25、50 和 100 厘米），最长的翼梁浮标容纳 SSLG，同时调整其自重。周期性波的实验结果得到了数值模型的充分支持，表明三柱梁设计与单柱梁设计相比，在寄生横摇振荡（三柱梁几乎没有观察到）和发电方面的性能都有显着提高。不规则波浪的初步数值模拟证实了三柱体的良好性能，特别是在“捕获宽度比”方面。未来的工作将在不规则波浪中测试 Trispar，并探索 SSLG 的动态调整策略（例如锁定），以进一步提高发电量。
We study free-floating point absorption wave generators, co nsisting of an assemblage of one or a few (mostly heaving) spar buoys, housing at least one short-stroke linear generator ( SSLG), made of a magnet, suspended to a spring, and oscillating within a coil. This system is aimed at producing low and renewable wave power (up to kW) for marine coastal surveillance systems. Both scale model experiments and numerical modeling are performed in order to tune the system’s parameters and maximize its response for a target sea-state (i.e., operate near reso nance in heave and magnet motion). We find that, for such buoy systems, viscous friction is the dominant damping mechanism near resonance and, hence, the buoy’s wet extremities must also be pro perly streamlined, and rolling must be minimized as it may significantly increase such damping. This can be achieved with a so-called trispar system, in which 3 spars buoys of identical diameter are mounted in an equilateral triangle configuration , one diameter apart from each other. Since the heave resonance period of a spar buoy is primarily a function of its draft, to lower th is period and better match the resonance period of the SSLG, the draft of each buoy in the trispar is varied (in the scale model, to 25 , 50 and 100 cm), with the longest spar buoy housing the SSLG, while simultaneously adjusting their dead weight. Experimental results in periodic waves, well supported by numerical modeling, show a significantly improved performa nce of the trispar vs. single spar design, both with respect to parasitic roll oscillations (almost none observed for the tripar) and power gene- ration. The good performance of the trispar, particul arly in terms of “Capture Width Ratio”, is confirmed by preliminar y numerical simulations in irregular waves. Future work will test the trispar in irregular waves and explore dynamic tuni ng strategies (e.g., latching) of the SSLG, in order to further improve power generation.