水流作用下重力式网箱网衣张力分布

Tension distribution of gravity cage net in steady current

在水流作用下,网箱网衣要承受很大的水流作用力,在网箱实际使用中破网逃鱼现象时常发生。网衣属于柔性结构物,在外部荷载作用下会发生较大的变形和位移,因此其受力和变形特性较为特殊。为了获得水流作用下重力式网箱网衣的张力分布,从而为设计和生产提供理论参考依据,利用集中质量的方法建立了水流作用下网箱网衣受力和变形的数学计算模型。利用此数学模型对重力式网箱网衣在不同配重模式和网目形状下的变形和张力分布进行了数值模拟。通过数值模拟研究发现,网箱网衣张力分布形式和网目形状关系密切,配重形式对其影响较小。相同工况条件下,配置底圈时网衣所受最大张力略大于单独沉子配重形式,同时菱形网目网衣所受最大张力略大于正方形网目的受力。

Fishing net should have enough intensity to withstand the attack of current and stormy waves to avoid fishing escape. Differing from other structures made from rigid materials,the intrinsically flexible nets undergo large deformation under external and internal forces. In addition, the length of netting twine undergoes extensional deformation as a result of various loads during fishing operation. The aim of this paper is to investi- gate the shape and tension distribution of fishing nets in current only. Herein, a numerical model is developed, based on lumped masses method ,and then the tension distribution in gravity cage net is demonstrated by images and positions where maximum of tension occurs are pointed out for the reference of practical application. According to the simulated data, it can be found that the distribution in the cage net is related to the style of weighting model, and the largest value of tension force in cage net with sinker only （WA） is smaller than that in cage net with bottom-collar sinker weight system （WB） in the same current condition.