| 摘要: |
| 依据波浪理论，分析了波浪经过网衣后的流体特性和边界条件，研究了网衣的波浪水动力、波浪透射系数与网衣尺度、特征参数、波浪参数等的关系。设计预加张力放射系泊法进行网衣构件水槽波浪试验。试验构件由10种PE网衣和HDPE框架装配而成，试验工况是规则波，周期为0.8—2.0s，波高为50-250mm。结果表明，作用在网衣上的水平波浪力变化规律与波浪基本一致，呈现周期性和不对称性变化；波浪力变化曲线呈现司托克斯二阶波形状，波峰较陡，波谷较平坦，和波面图相似；网衣水平波浪力周期峰值大约与波高的2.6次方、波长的0.8次方成比例，与网衣宽度z线性相关；随着特征参数d/a增大，网衣波浪力呈线性增加变化，透射系数减少，网衣消浪能力主要集中在网衣水表层。同时设计多层网衣组合的柔性浮式防波堤波浪试验，其消浪能力除了与网衣尺寸、特征参数等相关以外，还与网衣间隔距离有一定的关系。水槽试验时波浪最小透射系数下降到71％左右，从经济、实用角度表明，可用网衣来制作能防护渔业设施的柔性浮式防波堤。 |
| 关键词: 网衣，防波堤，波浪力，透射系数，波浪试验 |
| DOI： |
| 分类号: |
| 基金项目:国家863高技术发展计划资助项目，2003AA623030号；国家星火计划项目，2006EA700120号；浙江省科技厅资助项目，2006C32002号；浙江省自然科学基金资助项目，x506309号。 |
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| HYDRODYNAMIC FEATURE OF FISHING NET UNDER WAVE ACTION IN FLUME EXPERIMENT |
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SONG Wei-Hua1,2, LIANG Zhen-Lin3, HUANG Liu-Yi3, LU Yong-Lin4, CHEN BoHai5
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1.Zhejiang Ocean University;2.Ocean
University ofChin;3.Ocean University of China;4.Wenzhou Fisheries Technique Popularizing Center;5.Physical Ocean Key Open Laboratory，Ocean University of China
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| Abstract: |
| In the present study，the scattering of surface waves through a flexible net is studied in hydrodynamics．The net was modeled as a flexible hollow barrier in deferent tensions and looseness，for understanding how waves pass the net in transmission and reflection，as it was observed that the water inside a net is always much quiet than that outside．The experiment was designed using radial moorings to fix the net frames onto a flume with changeable tensions，under diferent hydraulic conditions to mimic regular wave action．The artificial wave periods and height were 0.8—2.Os and 50-250mm respectively．and the wave force on the cage and other parameters were recorded simultaneously．The boundary value problem were solved by defining the
transmission coefficient in terms of velocity potential to establish a full solution applying proper eigenfunction expansion，least square approximation，and cubic spline methods．The variations of the transmission coefficient，hydrodynamic pressure and surface wave elevation were determined with respect to the net length and other geometric parameters．
The results showed that the horizontal wave force on the net changed periodically and asymmetrically in physics．The period of the force coincided with that of the wave phase，while the asymmetrical nature of the wave force was resuhed from wave elevations in the shape of Stokes second-order wave with sharp peak and flat trough．The calculation shows that the net-undergoing force is correlated positively in the powers of 2.6 and 0.8 to wave height and length respectively．Moreover，as the net become more flexible，its transmission coefficient increased，more water can pass through，and the reflection coefficient and the hydrodynamic force were reduced．The net behaves like a hollow device allowing more wave energy to act on its surface and hence reduce the reflection and wave forces．At last，a multi-layered flexible floating-breakwater with was designed for flume-test．by which net transmission coefficient could be reduced to 71％．It implied that a feasible net cage could be applied in wavy environment to replace rigid breakwaters． |
| Key words: Fishing net,Breakwater,Wave mechanics,Transmission coefficient,Flume experiment |
