摘要
污损生物的大量附着会堵塞网箱网目、降低网箱内水流交换、增大网箱结构荷载和变形,从而导致在恶劣海况下网箱损坏风险加大,可能造成重大经济损失。为了研究污损生物附着对网箱网衣水动力特性的影响,本研究通过在海上网箱养殖区进行现场挂网实验,获得不同生物附着程度的网片(S_(n)=0.213~0.442),分析污损生物组成结构,并利用水槽实验探究不同水流速度(u=0.2~0.5 m/s)及不同冲角(θ=0°~90°)条件下水螅类污损生物附着网片的水动力特性。结果显示,水螅类生物附着程度随网片浸没时间先增后减,附着程度最大出现在第4周水深4.5 m处,网片湿重与附着程度正相关;水螅类污损生物的附着显著改变了网片水动力特性,附着程度最严重的网片(S_(n)=0.442)阻力与干净网片(S_(n)=0.146)的最大阻力相比增大至6.09倍,最大升力增大至5.99倍;水螅类生物附着的网片在不同冲角下对水动力系数的影响存在明显差异,阻力系数相对于干净网片可增大2.1倍,升力系数也相应地增大2.0倍;冲角为90°时,水螅类生物附着网片的阻力系数与密实度的拟合关系式为C_(d)=0.42+8.98S_(n)-7.78S_(n)2(R^(2)=0.803,S_(n)=0.145~0.442)。研究表明,水螅类污损生物的附着将明显增大网箱网衣的水动力荷载并将加剧网衣受力不均,导致迎流面网衣面临更高的损坏风险,在网箱设计和安全评估过程中必须综合考虑网衣升阻力变化对网箱结构安全性的影响,同时在网箱养殖生产过程中应及时清除网衣污损生物以确保结构安全。本研究可为网箱的设计和优化以及网衣清洗提供参考,有助于提升网衣系统的耐用性。
The massive attachment of fouling organisms will clog the net of fish cages,reduce the water exchange within the cages,and increase the structural load and deformation,which will lead to an increased risk of damage to the cage under severe sea conditions,and may cause significant economic losses.This study conducted a field test by deploying nets in marine cage aquaculture areas,obtaining nets with varying levels of biofouling(S_(n)=0.213-0.442)to study the effects of fouling organisms on the hydrodynamic characteristics of fish cage nets.The composition of the fouling organisms was analyzed,and flume tests were conducted to explore the hydrodynamic characteristics of hydroid-fouled nets for different flow velocities(u=0.2-0.5 m/s)and angles of attack(θ=0°-90°).The results indicated that attachment of fouling organisms initially increased and then decreased with the duration of immersion time,with the maximum attachment occurring at a depth of 4.5 meters during the fourth week.There was a positive correlation between the wet weight of the net and the degree of attachment.Notably,the attachment of fouling organisms like hydroids significantly alters the hydrodynamic characteristics of the nets.The net with the most severe fouling(S_(n)=0.442)exhibited a 6.09-fold increase in maximum drag force and a 5.99-fold increase in maximum lift force compared to a clean net(S_(n)=0.146).The influence of hydroid-fouled nets on their hydrodynamic coefficients under varying angles of attack exhibits notable differences,the drag coefficient could increase by as much as 2.1 times,and correspondingly,the lift coefficient underwent a 2.0-fold enhancement,in comparison to clean nets.At an angle of attack of 90°,the relationship between the drag coefficient(Cd)and solidity ratio(Sn)of the hydroid-fouled nets was well-fitted by the equation C_(d)=0.42+8.98S_(n)-7.78S_(n)2(R^(2)=0.803,S_(n)=0.145~0.442).Our research showed fouling organisms,like hydroids,significantly affected the hydrodynamic loads on fish cage nets,worsening stre
作者
刘融萍
黄六一
毕春伟
孙名山
张远茂
LIU Rongping;HUANG Liuyi;BI Chunwei;SUN Mingshan;ZHANG Yuanmao(Fisheries College,Ocean University of China,Qingdao 266000,China)
出处
《水产学报》
CAS
CSCD
北大核心
2024年第12期120-130,共11页
Journal of Fisheries of China
基金
国家自然科学基金(32473215)
山东省泰山学者工程专项经费(tsqn202312091)
青岛市海洋科技创新示范工程项目(23-1-3-hysf-2-hy)。
