基于网具模型试验的金枪鱼围网性能分析

Performance analysis of a tuna purse seine model

模型试验根据田内准则,选择大小尺度比分别为：λ=20∶1,λ￠=1∶1,制作的模型网规格为：网衣长109 m,网高15.6 m,上纲80.9 m,下纲98 m,下纲基本重量为0.663 kg/m,浮力配备25 N/m,模型网和实物网的缩结系数相同。试验结果显示,围网中部下纲沉降深度（D）和时间（t）的关系：D=–0.0014t2＋0.276t–0.6476（R2=0.9953）;下纲重量对沉降性能有显著影响,而放网速度对沉降性能的影响并不显著,但两者交互项对沉降深度有显著影响;在0.531～0.663 kg/m的范围内,随下纲重量增加,沉降深度呈大幅度增加趋势,而沉降速度呈递减趋势;在0.663～0.759 kg/m范围内,沉降深度小幅度递减,而沉降速度大幅度提高。当下纲重量为0.663 kg/m时,沉降速度随放网速度的增加而增加;随着沉降时间的增加,下纲张力在0～20 s范围内波动较大,之后保持一定的平稳状态。本研究通过对金枪鱼围网模型网制作的分析与探讨,旨在更好地通过模型试验研究金枪鱼围网网具性能。

The model purse seine was prepared following Tauti＇s modeling law and actual cases. The dimensions of the model purse seine were： float line length, 80.9 m; maximum net height, 15.6 m; lead line length, 98 m; basic lead line weight, 0.663 kg/m; and float line buoyancy, 25 N/m. The same hanging ratio was used for the model net and the full-scale purse seine. The results show that the relationship between sinking depth （D） and time （0 for the middle section of the lead line was described by the formula： D=-0.0014t2 ＋ 0.276t-0.6476 （R2=0.9953）. Lead line weight, but not setting speed, had a significant effect on sinking performance, while the interaction effect caused by these two factors was significant on sinking depth. Lead line weight of 0.531-0.663 kg/m increased sinking depth significantly, whereas sinking speed showed a decreasing trend. Lead line weight of 0.663-0.759 kg/m decreased sinking depth slightly, whereas sinking speed improved significantly. A lead line weight of 0.663 kg/m resulted in a tendency that sinking speed increased as setting speed increased. As sinking time increased, tension on the lead line of 0-20 s fluctuations was needed to maintain a steady state. Constructing the mode net is an important part of a model test and is directly related to the model test results. In this study, we constructed a tuna purse seine model to better understand tuna purse seine performance.