Comparative analysis of dynamic stability characteristics of T0 and T90 codends
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摘要: 改变网目使用方向是提高网囊选择性的主要方式之一，但易造成网囊水动力性能发生变化。为了量化T0 (传统菱形网目，即网衣纵目使用) 和T90 (网目旋转90°，即网衣横目使用) 两种网目使用方向下的网囊水动力和稳定性差异，利用循环动水槽试验，对T0和T90网囊在不同渔获量和网线直径条件下的形态、阻力和振荡变化进行测试分析。结果表明，T90网囊中段无明显收缩，中段网目张开角度约为T0网囊的1.2倍，且中段宽度明显大于T0网囊；T90网囊阻力大于T0，且模拟渔获物量每增加1倍，T90网囊阻力增加值约为T0的1.09倍。网囊存在渔获物时，T90网囊阻力振幅较T0大，采用T90网目的网囊会增加网囊阻力振幅，且随流速和渔获量的增加而增大。空网网囊纵向位移振幅和流速不存在明显关系。T0网囊纵向位移振幅较T90大，且随流速和渔获量的增加而增大，随网线直径的增加而减小。粗直径T90网囊有助于提高网囊的选择性和稳定性，但加大了网囊水阻力。研究结果可为优化网囊结构、改善网囊选择性，实现高效稳定的中层拖网作业提供基础科学数据。Abstract: Changing mesh orientation is a key appraoch to enhancing codend selectivity, but it may also alter the hydrodyna-mic performance of the codend. In order to quantify the differences in hydrodynamic and stability between T0 (A diamond mesh) and T90 (A 90°turned mesh) codends, we investigated the hydrodynamic characteristics, geometric shape, and fluttering motions of T0 and T90 codends with different twine diameters under varying flow velocities and catch sizes in a flume tank. Results show that the mesh opening angle in the middle part of T90 codend was approximately 1.2 times larger than of T0 codend. Moreover, the middle section of T90 codend had less shrinkage and greater width than T0 codend. The drag of T90 codend was, on average, larger than that of T0 codend and increased by 1.09 times with the simulated catch size. During the catch stage, the amplitude of the drag oscillations of the codend increased with increasing flow velocity and catch size, with T90 codend exhibiting larger amplitudes than T0 codend. There was no significant correlation between longitudinal displacement amplitude of the empty codend and current speed. Additionally, longitudinal displacement oscillations amplitudes in T0 codend were higher than those in T90 codend. The longitudinal displacement oscillations amplitudes in both codends increased with catch size and current speed, but decreased with twine diameter. The use of a thick diameter T90 codend can improve selectivity and stability, and increase the hydraulic resistance of the codend. The findings of this study can be applied to enhance the hydrodynamic characteristics, selectivity and stability of mid-water trawl codend.
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Key words:
- Codend /
- Mesh orientation /
- Drag /
- Simulative catch size /
- Oscillation characteristics
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图 3 网囊侧视图 (左：T0 网囊；右：T90 网囊)
Figure 3. Side view of codend (Left: T0 codend; Right: T90 codend)
图 5 渔获物在各流速下网囊水阻力的关系
Figure 5. Relationship between drag of codend with catches and current
表 1 网囊规格及参数
Table 1. Specifications and parameters of codend
网线材料Twine material 网线直径Twine diameter/mm 网目尺寸Mesh size/mm 拉直长度Length/cm 剪裁斜率Cutting ratio 网囊 Codend(Part 2) T0 PE 1.11 40 150 T90 PE 0.96 40 150 T90 PE 1.04 40 150 T90 PE 1.11 40 150 延伸区 Extension(Part 1) T0 PE 1.11 40 48 4∶1 T0 PE 1.11 40 48 4∶1 T0 PE 1.11 40 48 4∶1 T0 PE 1.11 40 48 4∶1 注：PE表示聚乙烯材料。 Note: PE represents polyethylene material. 
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表 2 60~90 cm之间网目张开角度
Table 2. Opening angle of mesh between 60–90 cm
模拟渔获物质量Simulated catch mass/kg 网目使用方向Mesh orientation 网线直径Twine diameter/mm 不同流速下的网目张开角度mesh opening angle at different flow velocity/(°) 0.4m·s−1 0.5m·s−1 0.6m·s−1 0.7m·s−1 0 T90 0.96 37 35 36 33 T90 1.04 44 41 41 38 T90 1.11 50 46 44 42 T0 1.11 42 37 36 35 1.35 T90 0.96 35 33 33 35 T90 1.04 40 39 39 37 T90 1.11 47 44 42 40 T0 1.11 40 38 33 34 2.70 T90 0.96 35 35 37 33 T90 1.04 37 36 36 34 T90 1.11 42 40 42 39 T0 1.11 39 34 36 31 4.05 T90 0.96 33 35 33 32 T90 1.04 35 34 34 34 T90 1.11 40 36 39 35 T0 1.11 36 34 31 28
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表 3 T0和T90网囊在不同渔获量和流速下的阻力振幅
Table 3. Drag amplitude of T0 and T90 codend with different catches and flow velocities
模拟渔获物质量Simulated catch mass/kg 网目使用方向Mesh orientation 网线直径Twine diameter/mm 阻力振幅 Resistance amplitude/N 0.4m·s−1 0.5m·s−1 0.6m·s−1 0.7m·s−1 0 T90 0.96 0.036 0.021 0.057 0.096 T90 1.04 0.012 0.027 0.043 0.084 T90 1.11 0.011 0.023 0.035 0.071 T0 1.11 0.012 0.025 0.045 0.097 1.35 T90 0.96 0.027 0.054 0.123 0.198 T90 1.04 0.044 0.075 0.133 0.215 T90 1.11 0.031 0.061 0.097 0.191 T0 1.11 0.015 0.031 0.051 0.091 2.70 T90 0.96 0.045 0.137 0.160 0.199 T90 1.04 0.059 0.144 0.277 0.332 T90 1.11 0.037 0.079 0.145 0.187 T0 1.11 0.027 0.09 0.106 0.123 4.05 T90 0.96 0.092 0.147 0.222 0.365 T90 1.04 0.197 0.267 0.307 0.337 T90 1.11 0.081 0.165 0.264 0.327 T0 1.11 0.199 0.232 0.226 0.295
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表 4 T0和T90网囊在不同渔获量和流速下纵向的位移振幅
Table 4. Longitudinal displacement amplitude of T0 and T90 codends with different catches and flow velocities
模拟渔获物质量Simulated catch mass/kg 网目使用方向Mesh orientation 网线直径Twine diameter/mm Displacement amplitude/cm 0.4m·s−1 0.5m·s−1 0.6m·s−1 0.7m·s−1 0 T90 0.96 0.121 0.151 0.153 0.209 T90 1.04 0.101 0.133 0.111 0.225 T90 1.11 0.114 0.121 0.108 0.141 T0 1.11 0.144 0.151 0.231 0.373 1.35 T90 0.96 0.210 0.267 0.303 0.321 T90 1.04 0.155 0.173 0.279 0.304 T90 1.11 0.124 0.146 0.228 0.281 T0 1.11 0.261 0.242 0.324 0.353 2.70 T90 0.96 0.337 0.371 0.394 0.396 T90 1.04 0.227 0.288 0.293 0.348 T90 1.11 0.101 0.142 0.253 0.359 T0 1.11 0.419 0.462 0.475 0.514 4.05 T90 0.96 0.245 0.378 0.541 0.601 T90 1.04 0.286 0.297 0.469 0.585 T90 1.11 0.238 0.281 0.357 0.448 T0 1.11 1.654 1.809 2.432 2.591
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[1] WILEMAN D, FERRO R S T, FONTEYNE R, et al. Manual of methods of measuring the selectivity of towed fishing gear[R]. Copenhagen: ICES Cooperative Research Report, 1996. [2] 臧迎亮, 虞聪达. 过滤性网渔具网囊网目扩张性能研究[J]. 浙江海洋学院学报 (自然科版), 2012, 31(4): 350-356. [3] HICKEY W M, BOULOS D L, BROTHERS G. A study of the influence of lastridge ropes on redfish selectivity in a bottom trawler[R]. Ontario, Canada: Department of Fisheries and Oceans, 1995. [4] CHENG Z, EINARSSON H A, BAYSE S, et al. Comparing size selectivity of traditional and knotless diamond-mesh codends in the Iceland redfish (Sebastes spp.) fishery[J]. Fish Res, 2019, 216: 138-144. doi: 10.1016/j.fishres.2019.04.009 [5] PRIOUR D. Modelling axisymmetric codends made of hexagonal mesh types[J]. Ocean Eng, 2014, 92: 1-11. doi: 10.1016/j.oceaneng.2014.09.037 [6] HERRMANN B, PRIOUR D, KRAG L A. Simulation-based study of the combined effect on codend size selection of turning meshes by 90° and reducing the number of meshes in the circumference for round fish[J]. Fish Res, 2007, 84(2): 222-232. doi: 10.1016/j.fishres.2006.10.020 [7] MADSEN N, HERRMANN B, FRANDSEN R P, et al. Comparing selectivity of a standard and turned mesh T90 codend during towing and haul-back[J]. Aquat Living Resour, 2012, 25(3): 231-240. doi: 10.1051/alr/2012021 [8] HANSEN U J. Performance of a trawl codend made from 90 turned netting (T90) compared with that of traditional codends[R]. Gdynia: Paper presented at the ICES Fishing Technology and Fish Behaviour Working Group Meeting, 2004. [9] MADSEN N, HANSEN K, MADSEN N A. Behavior of different trawl codend concepts[J]. Ocean Eng, 2015, 108: 571-577. doi: 10.1016/j.oceaneng.2015.08.047 [10] CHENG Z H, PAUL D W, DAVID K. Hydrodynamic performance of full-scale T0 and T90 codends with and without a codend cover[J]. Ocean Eng, 2022, 10(3): 440. [11] O'NEILL F G, O'DONOGHUE T. The fluid dynamic loading on catch and the geometry of trawl codends[J]. Proc R Soc A Math Phys Eng Sci, 1997, 453: 1631-1648. doi: 10.1098/rspa.1997.0087 [12] WAN R, JIA M X, GUAN Q L, et al. Hydrodynamic performance of a newly-designed Antarctic krill trawl using numerical simulation and physical modeling methods[J]. Ocean Eng, 2019, 179: 173-179. doi: 10.1016/j.oceaneng.2019.03.022 [13] MADSEN N, TSCHERNIJ V, HANSEN K, et al. Development and testing of a species-selective flatfish otter trawl to reduce cod bycatches[J]. Fish Res, 2006, 78(2/3): 298-308. [14] BOUHOUBEINY E, GERMAIN G, DRUAULT P. Time-resolved PIV investigations of the flow field around rigid codend net structure[J]. Fish Res, 2011, 108: 344-355. doi: 10.1016/j.fishres.2011.01.010 [15] THIERRY N N B, TANG H, XU L X, et al. Identifying the turbulent flow developing inside and around the bottom trawl by Electromagnetic Current Velocity Meter approach in the flume tank[J]. J Hydrodynam B, 2021, 33(3): 636-656. doi: 10.1007/s42241-021-0058-0 [16] JONES E G, SUMMERBELL K, O'NEILL F. The influence of towing speed and fish density on the behaviour of haddock in a trawl codend[J]. Fish Res, 2008, 94(2): 166-174. doi: 10.1016/j.fishres.2008.06.010 [17] TANG H, HU F X, ZHOU C, et al. Variations in hydrodynamic characteristics of netting panels with various twine materials, knot types and weave patterns at small attack angles[J]. Sci Rep, 2019, 9(1): 1923. doi: 10.1038/s41598-018-35907-1 [18] HU F, MATUDA K, TOKAI T. Effects of drag coefficient of netting for dynamic similarity on model testing of trawl nets[J]. Fish Sci, 2001, 67(1): 84-89. doi: 10.1046/j.1444-2906.2001.00203.x [19] 陈明鑫, 许柳雄, 唐浩, 等. 基于多元变量的南极磷虾拖网作业状态影响因素分析[J]. 上海海洋大学学报, 2021, 30(1): 144-154. [20] 李俊伟. 基于小波变换的韩江年径流多时间尺度演变特征分析[J]. 广东水利水电, 2014(4): 5-7, 10. doi: 10.3969/j.issn.1008-0112.2014.04.002 [21] SISTIAGA M, HERRMANN B, NIELSEN K N, et al. Understanding limits to cod and haddock separation using size selectivity in a multispecies trawl fishery: an application of FISHSELECT[J]. Can J Fish Aquat Sci, 2011, 68: 927-940. doi: 10.1139/f2011-017 [22] HERRMANN B, SISTIAGA M, NIELSEN K N, et al. Understanding the size selectivity of redfish (Sebastes spp.) in North Atlantic trawl codends[J]. J Northwest Atl Fish Sci, 2012, 44: 1-13. doi: 10.2960/J.v44.m680 [23] 杨吝. 不同结构网囊特性的初步研究[J]. 湛江海洋大学学报, 1998(2): 25-29. [24] HERRMANN B, WIENBECK H, MODERHAK W, et al. The influence of twine thickness, twine number and netting orientation on codend selectivity[J]. Fish Res, 2013, 145: 22-36. doi: 10.1016/j.fishres.2013.03.002 [25] 薄佳男, 林可, 马家志, 等. 高分子编结网片水动力特性水槽试验研究[J]. 渔业现代化, 2020, 47(1): 72-79. doi: 10.3969/j.issn.1007-9580.2020.01.010 [26] 张敏, 邹晓荣, 季星辉, 等. 东南太平洋公海水域智利竹䇲鱼探捕及其商业开发前景探讨[J]. 水产学报, 2005, 29(3): 386-391. [27] KIM H Y, LEE C W, SHIN J K, et al. Dynamic simulation of the behavior of purse seine gear and sea-trial verification[J]. Fish Res, 2007, 88(1/2/3): 109-119. [28] 唐浩, 张馨茹, 朱安然, 等. 网线直径和模拟渔获物对拖网网囊水阻力及形态影响[J]. 上海海洋大学学报, 2022, 31(3): 770-780. doi: 10.12024/jsou.20220303774 [29] BEARMAN P. Vortex shedding from oscillating bluff bodies[J]. Annu Rev Fluid Mech, 1984, 16: 195-222. doi: 10.1146/annurev.fl.16.010184.001211 [30] DRUAULT P, GERMAIN G. Analysis of hydrodynamics of a moving trawl codend and its fluttering motions in flume tank[J]. Eur J Mech B Fluids, 2016, 60: 219-229. doi: 10.1016/j.euromechflu.2016.06.010 [31] LIU W, TANG H, XU L X, et al. Effect of cutting ratio and catch on drag characteristics and fluttering motions of, mid-water trawl codend[J]. J Mar Sci Eng, 2021, 9(3): 256. doi: 10.3390/jmse9030256 -
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