阿根廷滑柔鱼底拖网水动力性能研究

Hydrodynamic performance of Argentine shortfin squid (Illex argentinus) bottom trawl

  • 摘要: 阿根廷滑柔鱼 (Illex argentinus) 为短生命周期的大洋性浅海种,是西南大西洋公海渔场重要的经济头足类,主要捕捞方式为鱿钓和底拖网。在阿根廷滑柔鱼底拖网作业过程中存在能耗高、船网匹配差等问题,需要对其水动力性能进行研究。以六片式小网目阿根廷滑柔鱼单船底拖网为母型网 200 m×113.8 m (84.6 m),按照田内准则 (大尺度比λ=30,小尺度比 λ'=5) 制作模型网,通过模型试验探究了拖速、浮沉比、水平扩张比 (袖端间距与下纲长度比值) 对底拖网网口高度、网具阻力、能耗系数和功率消耗的影响。结果表明,拖速为3 kn、水平扩张比 (L/S) 为0.54时,浮沉比从0.6增至0.7,网口高度从9.66 m增至14.1 m,阻力从73.73 kN增至83.48 kN,但随着拖速的增大,浮沉比对网口高度和阻力的影响降低;拖网网口扫海面积小于200 m2时,能耗系数受水平扩张比影响较大,反之,受网口高度影响较大;功率消耗随拖速和水平扩张比的增加而增大,拖速超过4.0 kn时,功率消耗占比船舶主机功率超过10%。

     

    Abstract: Illex argentinus, inhabiting in shallow waters with a short life cycle, is an important economic cephalopod in the high seas fishing ground of the southwest Atlantic Ocean. Squid jigging and bottom trawling are the main fishing patterns to catch this species. However, there are some problems in bottom trawl, such as high energy consumption, and poor matching between vessel and trawl. Thus, it is necessary to understand the hydrodynamic performance of bottom trawl for I. argentinus. In this paper, we conducted a model experiment in the dynamic water tank to explore the effects of towing speed, horizontal spreading ratio, buoyancy weight ratio on the hydrodynamic performance of height of net opening, resistance, coefficient of energy consumption and power consumption. The model net was designed based on the small mesh six-panel single boat bottom trawl used for the main capture of I. argentinus Main scale: 200 m×113.8 m (84.6 m). According to the Tauti's Law, the model experiment was scaled with the large scale ratio of 1∶30 and the small scale ratio of 1∶5. When the towing speed V was 3 kn and the horizontal spreading ratio L/S was 0.54, the buoyancy weight ratio increased from 0.6 to 0.7, the height of the net opening increased from 9.66 m to 14.1 m, and the resistance increased from 73.73 kN to 83.48 kN. However, with the increase of towing speed, the influence of the buoyancy weight ratio on the height of the net opening and resistance decreased. When the sweeping area of trawl opening was less than 200 m2, the energy consumption coefficient was greatly affected by the horizontal expansion ratio, on the contrary, it was greatly affected by the height of trawl opening. The power consumption increased with towing speed and horizontal spreading ratio. It accounted for more than 10% of main engine power for vessel when the towing speed was more than 4 kn.

     

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