高压射流式水下洗网机喷嘴的设计

为解决深水网箱养殖过程中因网衣附着生物而影响水体交换,并给换网及网衣清洗带来极大困难等问题,开发水下洗网机并提高水下洗网机的清洗效率,是深水网箱养殖的重要配套装备与技术。通过对高压射流水下洗网机工作原理的分析,基于能量方程,推导出洗网机关键部件喷嘴的结构几何参数计算表达式。合理选择高压水发生系统的压力和流量,计算出喷嘴的孔径与长径比。在此基础上计算高压射流水下洗网机的水力参数,为进一步优化洗网机结构提供理论依据。     

歧管式高压射流水下洗网机的设计

文章针对深水网箱养殖过程中岸电供应不便而给网衣的水下清洗带来极大困难的问题,研制了歧管式高压射流水下洗网机,克服了高压仓式洗网机水头损失大的缺点。通过水力学计算得到歧管式高压射流水下洗网机射流压力P=5．57MPa、喷嘴孔径d=2．6mm、射流速度v=104．1m·s。和射流功率P=12．3kW、射流反冲力F=234．96N。水下洗网机的海上清洗试验表明,在工作泵满足工作压力和设计流量条件下,歧管式高压水射流水下洗网机的综合性能达到了设计要求。     

高压水射流水下洗网机旋转射流打击力计算

依据水力学公式计算出歧管式高压水射流水下洗网机旋转的射流角速度和射流打击力。分析结果表明:旋转的射流打击力随偏转角增大而递减,但随射流压力、旋转半径和喷嘴孔径增大而增大;合理选择喷嘴孔径对旋转的射流打击力的增强作用明显,而增大旋转半径对射流打击力的增强作用较弱;旋转的射流打击力比非旋转的射流打击力更有利于提高清洗网衣的效率。海上清洗试验表明,在合理的压力和流量条件下,旋转的射流打击力清洗网衣的效果良好。     

基于ANSYS WorkBench的围网理网机优化设计

针对中国围网渔船作业机械化程度低、起放网速度慢等问题,围绕加快围网网具整理速度,提高整体作业的效率,开发了1.5T围网理网机。利用CREO三维建模软件建立理网机实体模型,并将建好模型导入ANSYS Work Bench中进行有限元受力分析,对理网机作业工况位置进行有限元分析计算,对最大应力结构部件进行优化分析设计,最终得到结构合理、强度满足安全系数的理网机部件参数。     

广东大麟洋:斥资1亿发展深水网箱养殖

正深水抗风浪网箱、自动投料机、水下监测系统、水下洗网机……这些听起来很"高大上"的名词都与广东大麟洋海洋生物有限公司(以下简称"大麟洋")有关。在广东省珠海市桂山大蜘洲海域,大麟洋建有现代渔业示范养殖基地,场内有现代抗风浪深水网箱400个,核准水域养殖面积为170.469公顷,是农业部水产健康养殖示范场。该场以金鲳鱼、黄花鱼为龙头产品,配套养殖鮸鱼、军曹鱼等,年产量达1万吨,2016年年产值达8千万元。     

应用Monte Carlo方法计算水上集鱼灯向下辐照度在一类海水中的分布

利用叶绿素浓度、海表风速数据及集鱼灯、渔船的相关特征参数(集鱼灯的配光曲线、波谱分布、辐射通量、集鱼灯在渔船上几何位置等),采用Monte Carlo方法构造了一个计算水上集鱼灯水下辐照度分布的模型。该模型利用叶绿素浓度数据、纯海水水光学特性及其与吸收、散射系数的关系计算波束衰减系数(包括吸收系数、散射系数),利用风速数据构造毛细波面,计算该波面对光路及菲涅耳反射的影响。该模型与传统计算方法相比,有如下优点:(1) 利用叶绿素浓度数据计算波束衰减系数,并考虑了波束衰减系数的波谱特征;(2) 能提供不同水层集鱼灯向下辐照度的光谱分布;(3) 能提供渔船阴影区向下辐照度的分布;(4) 考虑了毛细波面的影响,使集鱼灯水下辐照度的计算更合理;(5) 叶绿素浓度、风速数据可由遥感获取,使模型更易应用于实际计算。模型计算结果与实测值进行了比较,相对均方根误差为37.6%,但两者之间存在显著相关性(P<0.001),文中对模型结果进行了分析。     

基于成像声呐的鱼类三维空间分布

针对海洋牧场中鱼群的三维空间分布问题,本研究提出一种利用成像声呐进行位置计算的方法。将成像声呐固定在船舷外侧的水下,并保证波束发射方向和声呐移动方向一致,通过走航的方式采集水下鱼群信息。首先对采集的原始数据进行图像处理,包括图像构建、背景去除、目标提取等,然后利用基于交互式多模型联合概率数据关联算法对水下目标进行关联处理,得到同一个目标在声呐水平视场中不同帧图像中的对应关系,在此基础上根据连续两帧图像中目标位置关系计算目标的空间坐标,最后结合关联算法获得多目标在三维空间中的运动轨迹以及深度分布情况。研究表明,本方法可以有效获取鱼群在水下的三维运动轨迹及其分布情况,这将为鱼类行为分析以及海洋牧场的资源评估提供技术支持。     

新型双牵网机

双牵网机是辽宁省海洋水产研究所与协作单位共同研制的一种新型网机。该网机成网工序简单,改变了以往的抽丝、混线、编织过程,从投原料到产品网一气呵成,只需10分钟。从1984年研制成功以来,双牵网在全国各地进行了试用,效果较好,并在用户的要求下,先后在湖北、山东、安徽、大连等地技术转让八家。该项成果已获1985年农牧渔业部科技进步一等奖。 1.网机规格主机(45B型塑料挤出机)外形尺寸:1515×606×1526毫米;附机外形尺寸:9000×2500×     

信息总汇

养殖网箱的自走式水中洗网机日本最近研制一种可沿着网箱的网上自行移动并于水中对网箱侧面 ,底面进行洗净的机械。该机械由高压水泵站与洗净机二部分组成 ,高压水泵与其控制部分设在操作船上。洗净机的行走动力为螺旋浆 ,洗净机上装有水中摄像机 ,从而可以引导船上的操纵 ,并兼作网箱的检查 ,使用时有全自动及手动选择 ,并可在透明度差的水域中使用。该机洗网时不会将网衣拉起 ,从而丝毫不会影响网箱中的养殖鱼。鱼类保鲜中的 MAP技术MAP保鲜又称 MA包装或修饰气体贮藏。即将特定的混合气体注入鱼密封包装内以延长鱼类的货架期 ,常用的…     

艇滑道拖网渔轮应用卷袖网机的探讨

《渔业机械仪器》今年第一期(P51)刊登的《卷网机在国内外的应用》一文中提到：“……目前为什么日本渔船不采用卷网机原因尚不清楚。”使我联想到去年随辽宁省水产技术赴日考察团在日本的见闻。     

海水网箱网衣防污技术的研究进展

海水网箱养殖中,网衣污损附着物会影响网箱设施安全及其养殖鱼类的健康生长,因此,网衣防污是网箱养殖业备受关注的问题.本文在简述海水网箱网衣分类与特点的基础上,重点介绍了人工清除法、防污涂料法、机械清除法、金属合金网衣防污法、箱体转动防污法、生物防污法、网衣本征防污法等网衣防污技术最新研究进展;结合本课题组在网衣防污方面的...     

Hydrodynamic performance investigation on an upper and lower water exchange device

Water exchange is an important way to guarantee its good quality between surface and bottom seawater, and it plays a significant role in water environment and ecology as well as fish farming systems. The conceptual experiment (Yin et al., 2018) was extended to present an Upper and Lower Water Exchange Device for strengthening the vertical water exchange performance, and a 3-D CFD mathematical model combining with Reynolds-Averaged Navier-Stokes equations, standard k-ε equations and VOF technique was developed to investigate its hydrodynamic performance and the vertical water exchange capacity for regular waves. The extrapolated relative error and the grid convergence index were used to estimate the discretization error. A series of experiments were conducted to measure the wave surface and water velocity histories, the experimental data were used to validate the mathematical results, and they agreed well with each other. It was found that the inside water motion is determined mainly by the wave overtopping and water entrainment. Generally, the net flow rate decreases at first and then increases with increasing wave steepness. In addition, the ratio of crest freeboard height to incident wave height plays a significant role in water exchange performance. A small ratio leads to an upward movement of the inside water, whereas a high value contributes to a downward net flow to some extent. Finally, a simple formula on the net flow rate was deduced with the dimensional analysis method and the least squares method, and it was validated well with the related data.     

织网机械的研究（上）

一、前言网具是渔业生产中不可缺少的工具。将两根线打结连片成网的工艺过程是比较复杂的,可以用手工也可以实现机械化。国外广泛使用机器织网以提高生产率、及时满足渔业生产部门对网片的需要。织网机的规格型号虽多,但其种类不多,按其能编织网的类型来分——无结编网机、有结节织网机     

An automatic fishing machine based on acoustic conditioning

An automatic fishing machine based on acoustic conditioning was developed and tested in a reservoir. The floating fishing machine is remotely and automatically controlled to operate an underwater speaker, a feeder and underwater cameras that monitor fish behavior in real time. An open net pen installed under the system can be automatically closed to capture gathering fish. The dynamics of fish populations in the open net pen was monitored and discussed. Fish were conditioned to associate an acoustic signal with food by classical conditioning. Periodic retraining was used to reinforce the conditioned behavior of fish freely swimming in the reservoir. Fish were captured by calling them to the fishing machine using the acoustic signal and automatically closing the net pen around them: 2.5 times more fish were captured in such capture events than in control events, in which the net pen was automatically closed without calling the fish.     

海水网箱单养及混养褐篮子鱼试验效果初探

为探讨褐篮子鱼（Siganus fuscescens）的养殖模式和网衣清洁作用,在4只传统网箱中进行了不同养殖模式的试验。试验采用单养与混养模式（与日本黄姑鱼Nibea japonica、大黄鱼Pseudosciaena crocea混养）,设置空白对照组、单养组、混养组Ⅰ和Ⅱ。5个多月的养殖试验结果表明,混养组中褐篮子鱼的日增重率高于单养组,养殖成活率均在95％左右,无显著差异。与对照组相比,通过2个月的养殖,单养组和混养组网箱附着的裂片石莼（Ulvafasciata Delile）均被褐篮子鱼摄食干净。由此表明,褐篮子鱼喜欢摄食网衣附着藻类,因此可以减少网箱清洗工作量,并在混养时可提高单位水体的鱼产量。     

不同工作姿态下立式双曲面网板水动力及周围流场特性研究

网板是单拖网中实现网具扩张的重要属具,其稳定状态直接决定拖网网口扩张程度,进而影响渔获效率和经济效益。该研究以立式双曲面网板为研究对象,利用水槽模型试验和数值模拟(Computational fluid dynamics,CFD)探究立式双曲面网板在不同倾斜状态(内、外倾斜,前、后倾斜)和冲角下的水动力性能变化,并对网板周围流场和表面压力进行可视化。结果显示:1)模型试验和数值模拟的网板升力系数均在倾角为0°,冲角为25°时达到最大值,分别为1.69和1.88;而两者的阻力系数均随倾角增大逐渐减小。2)模型试验和数值模拟的升阻比均随倾角增大逐渐减小;当内倾角为5°时,两者的升阻比均达到最大,分别为3.27和3.69。3)压力中心系数Cpb随倾角变化基本保持不变;但当网板处于前倾状态时,Cpc随倾角增大而增加;而网板处于后倾状态时,Cpc随倾角增大逐渐减小。4)CFD结果显示,网板中心面后部旋涡随倾角增大逐渐减小;当网板处于内、外倾状态时,前端流速衰减区随倾角增大逐渐增加;但当网板处于前、后倾状态时,衰减区随倾角增大逐渐减小;网板处于前倾状态时,压力中心随倾角增大逐渐向网板上端翼弦移动,网板处于后倾状态时则出现相反结果。研究结果可为今后研究网板稳定性和合理使用及调整网板提供科学参考。     

机织单死结锦纶网片不同定型方向的断裂强力比较

本研究以国家有关测试标准为依据，采用裂区模型实验设计方法，对多种系列机织单死结锦纶网片试样进行测定，数据采用多元方差分析方法，分析了网片纵横向之 断裂强力和断裂伸长率的差异性，找出了影响网片断裂强力和断裂伸长率的主要因素，分析了各主要因素影响的程度和趋势。研究结果表明，机织单死结网片采用横向定型时，其断裂强力和断裂伸长率均大于采用纵向定型。     

Effects of water flow velocity and fish culture on net biofouling in fish cages

The effects of water flow, fish feed and cage position on net biofouling was examined in a floating cage fish farm. Fouling of 16 mm mesh net panels suspended inside and outside net cages and exposed to different treatments were monitored weekly until net apertures were completely occluded by the fouling organisms (8 weeks). Results indicate a dramatic reduction in water flow velocity throughout the fish farm due to the cage units themselves and net biofouling. The reduced water flow (<10 cm s^?1) inside net cages promoted rapid net biofouling, while rapid water flow outside the net cages (>25 cm s^?1) kept the net fouling organisms at bay. Although fish rearing in net cages with inputs of commercial pellet feed increased sessile biofouling (222% higher than outside the net cages) and non‐sessile biofouling (570% higher), the type of fish feed used did not significantly affect biofouling development. The study recommends that the geometry of serially arranged net cages, as commonly deployed in tropical tidal estuaries, be reconfigured to improve flow through in order to minimize the impact of fouling.