双开缝矩形曲面网板水动力性能及影响参数研究

为满足渔业现代化的发展需求,渔具的改良是其不可或缺的一部分,而网板是提供拖网网衣水平张力主要属具。采用矩形曲面网板有利于提高网板的升力系数和升阻比,而网板开缝有利于减小网板的背面涡流,增加网板的水动力性能,提高网板操作稳定性。为研究小型拖网渔船网板的水动力性能,通过数值模拟的方法,在其他参数一定的情况下,采用控制变量法控制双开缝矩形曲面网板的速度、开缝尺寸以及展弦比等参数的单一变化,研究其对拖网网板水动力性能的影响规律。数值计算结果表明:该网板升力系数和升阻比随冲角的增大呈先增后减的趋势,最佳升阻比出现在冲角为10°左右的时候;速度对网板水动力性能无显著影响;升力系数随开缝尺寸的增加总体呈上升趋势,当开缝尺寸大于50 mm时,升力系数无显著变化,升阻比随开缝尺寸增大总体呈先增后减的趋势;不同展弦比的网板在升力系数达到最大时对应的最佳冲角随展弦比的增加而逐渐减小;同时,升力系数峰值随展弦比的增加呈先增后减的趋势,当展弦比为0.6左右时,升力系数的峰值达到最大。研究结果可为同类型的小型拖网渔船拖网网板的结构优化设计提供更加可靠的参考。

Study on hydrodynamic performance and influence parameters of double-slitted rectangular cambered otter board

In order to meet the development needs of fishery modernization,the improvement of fishing gears is an indispensable part,and the otter board is the main attachment to provide horizontal tension of trawl nets.The use of a rectangular curved mesh plate for the otter board is beneficial to increase the lift coefficient and the lift-to-drag ratio of the otter board and the otter board opening is advantageous for reducing the back vortex of the otter board,increasing the hydrodynamic performance of otter board and improving the operational stability of the otter board.In order to study the hydrodynamic performance of small trawler otter boards,this paper mainly used the numerical simulation to control the angle of attack of the double-slitted rectangular cambered otter boards with the control variable method under certain parameters.A single change in parameters such as slit size,and aspect ratio was applied to study the effects of changes on the hydrodynamic performance of the trawl otter boards.The numerical results showed that the lift coefficient and lift-drag ratio of the otter board increased first and then decreased with the increase of the angle of attack.The best lift-to-drag ratio occured when the angle of attack was about 10°;the performance had no significant effect;the lift coefficient generally increased with the increase of the slit size.When the slit size was larger than 50mm,the lift coefficient did not change significantly,and the lift-to-drag ratio increased first and then decreased with the increase of the slit size;when the lift coefficient reached the maximum,the corresponding angle of the otter board with different aspect ratios decreased with the increase of the aspect ratio.At the same time,the peak of the lift coefficient increased first and then decreased with the increase of the aspect ratio.When the aspect ratio was about 0.6,the peak of the lift coefficient reached the maximum.The results of this study can provide a more reliable reference for the structural optimization design of the same type of small trawler otter board in the future.