筏式养殖区垂向流速分布特征试验研究

贝类筏式养殖在海水养殖中占据重要地位。近年来,随着养殖规模逐渐扩大,筏式养殖的弊端也随之显现出来。大面积筏式养殖网笼的布置,对海洋潮流流速产生阻碍作用,引起水体交换能力下降、污染物堆积等问题。因此研究筏式养殖垂向流速区分布特征,可为养殖规模控制、污染防治等提供科学参考。该文首先收集了筏式养殖及流速变化的相关资料,整理了筏式养殖区区域特征及养殖概况,根据养殖区实际情况,取长度比尺1??20,制作了筏式养殖的物理模型。然后在波流水槽中进行11组试验,探究了养殖区内外流速在不同水深、来流速度、养殖密度条件下的变化情况。结果表明:(1)筏式养殖模型的存在,会对来流造成明显的阻碍作用,表层流速减小较多。(2)养殖区内部断面平均流速相比于来流减小约15%。(3)养殖区前方流速变化较小,养殖区后方流速变化较大。(4)养殖水深越浅,来流速度越小,养殖密度越大,养殖区对来流的影响程度越大。

Physical experiments on vertical velocity distribution of raft-culture area

Scallop raft-culture plays an important role in Qinhuangdao area.In recent years,with the expanding of scallop farms and the increase of aquaculture density,the disadvantages have gradually appeared.Large area of suspended aquaculture system can damp the tidal flow dramatically in the raft-culture and cause problems such as decrease of water exchange and accumulation of pollutants.Therefore,this study focuses on vertical velocity distribution in raft-culture area,which can provide a reference for the researches on raft-culture and supports for government management.Literatures of velocity of raft-culture and the data of the studied area are collected and analyzed,which lay a solid foundation for further study.Firstly,based on the situation of raft-culture,the physical models are made with a length scale ratio of 20 (λ1 =20).Then 11 experimental tests are conducted in the laboratory flume,which study the velocity variations in raft-culture area under different water depths,ambient flow velocities and aquaculture densities.The results indicate that:(1) when the model exists,it can cause obvious impediment to the flow,which leads to the velocity decrease in the model area,especially in the surface layer.(2) The reduction of average velocity in the cross-section in raft-culture area is about 15％ compared to the inflow.(3) The backside of the model suffers more flow velocity reduction than its front.(4) The shallower water depth,the slower inflow velocity and the larger aquaculture density,the more severe velocity reduction will be in the aquaculture area