基于正交试验方法的四片式虾拖网结构参数优化

针对规格为40.3 m×(20.8~16.2)m的我国过洋性虾拖渔业四片式虾拖网,基于L_9(3~4)正交表,设计了网身长度(L_b)、下网袖长度(L_w)、侧网宽度(W_S)3种因素各3个水平的正交试验,并利用方差分析检测3种试验因素对网具阻力、能耗系数、L/R(袖端间距与阻力之比)系数影响的显著性,旨在对此种网具的网身长度与网口周长之比(L_b/C)、下网袖长度与网口周长之比(L_w/C)、侧网宽度与上网片宽度之比(W_S/W_U)这3种结构参数进行优化。结果表明,对网具阻力的影响因素由主到次依次是下网袖长度、网身长度、侧网宽度。对能耗系数的影响因素在水平扩张L/S(袖端间距/下纲长度)=0.45时由主到次依次是侧网宽度、网身长度、下网袖长度;但在水平扩张L(袖端间距)=10 m时,下网袖长度为主影响因素。对L/R系数的主影响因素为下网袖长度。此类型网具的L_b/C应比小网目底层拖网略小,但在较大的范围内(0.26~0.38)变化亦不会对网具水动力性能有显著影响。L_w/C=0.31为试验的最佳水平,下网袖长度为3种因素中对网具性能影响最显著的因素。W_S/W_U=0.19为试验的最佳水平,侧网宽度应优先满足虾拖网作业对网口高度的要求,在此基础上,尽量缩小W_S/W_U值,不必拘泥于W_S/W_U结构参数值。

Optimization of the structural parameters for four-panel shrimp trawl nets based on orthogonal experimental design

This study concerns the Chinese distant-water shrimp-trawl fishery effort which uses four-panel trawl nets with the specification 40.3 m × (20.8?16.2) m. Based on the L9(34) orthogonal array, the orthogonal experi-ment of three factors body length (Lb), lower wing lengh (Lw) and meshes of side pannel] in each level was de-signed to optimization three structural parameters ofLb/C,Lw/C andWS/WU, by analyzing the effect of three ex-perimental factors changing on the level of test resistance of the net, the coefficient of energy consumption, and the coefficient ofL/R. The results showed that the resistance of the net was primarily affected byLw,Lb, andWS in a descending sequence. The coefficient of energy consumption was primarily affected byWS,Lb,Lw in a de-scending sequence whenL/S=0.45; but whenL=10 m,Lw was the main influencing factor and the main influencing factor of the coefficient ofL/R. TheLb/C of this type of net should be slightly smaller than used in small-mesh bottom trawls, but in a larger range (0.26?0.38) the change did not show a significant impact on the hydrodynamic performance of the nets. The best level of the experiment was whenLw/C=0.31, andLw was the most significant factor among the three factors. And the best level of the experiment was whenWS/WU=0.19, andWS only needed to meet the height of the net mouth when trawling for shrimp, and given a priority to expand the horizontal distance of the net, was not concerned with the structural parameter ofWS/WU.