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Experimental study on hydrodynamic characteristics of polymer knitted netting

  

  1. (1 Fishery College of Zhejiang Ocean University , Zhejiang Provincial Key Laboratory of Marine Fisheries Equipment and Technology. Zhoushan, 316000, China;
    2 Tokyo University of Marine Science and Technology, Tokyo, 1080075, Japan)
  • Online:2020-04-30 Published:2020-02-20

高分子编结网片水动力特性水槽试验研究

  

  1. (1浙江海洋大学水产学院,浙江省海洋渔业装备技术研究重点试验室,浙江 舟山 316000;
    2日本东京海洋大学,日本 东京,1080075)
  • 通讯作者: 宋伟华(1968—),男,教授,研究方向:海洋渔业。E-mail:whsong6806@163.com
  • 作者简介:薄佳男(1995—),男,硕士研究生,研究方向:渔具渔法与渔业工程技术。E-mail:278837249@qq.com
  • 基金资助:
    浙江省重点研发计划项目(2018C02040);浙江省自然科学基金项目(LY14C190005,Q14C190005);浙江省海洋渔业装备技术研究重点试验室资助项目(MFET201406);浙江省一流学科开放课题资助项目(20160021)

Abstract: The application of polymer fishery materials in facility culture and marine fishery is more and more extensive, so it is necessary to study its hydrodynamic characteristics. The polymer knitted netting with different solidity ratio and wire thickness was used for the flume test, with inclined angle changing from 0 °to 90 ° and the flow velocity set from 0.3m/s to 1.3m/s at the gradient of 0.1m/s. In order to reduce the influence of wake flow and turbulence on the test results, the streamlined frame was used in fitting out .The test results are as follows: (1) the drag coefficient increases with the increase of the solidity ratio when the netting is normal to the water flow and decreases with the increase of the solidity ratio when the netting is parallel to the water flow. (2) The drag coefficient is decreased gradually with the increase of Reynolds number. When the netting is normal to the velocity of fluid movement, the drag coefficient is steady in the range of 1 300<Re<2 000.When the netting is parallel to the velocity of fluid movement, the drag coefficient changes little after Re>1500. (3) The drag coefficient increases with the increase of the angle of incidence and finally tends to be stable. (4) The lift-drag ratio (K) increases first and then decreases with the increase of inclined angle in general, with the extreme value between 20 °and 30 ° and the maximum value about 0.41. (5)When the netting is normal to the water flow, in the range of 1 000<Re<2 000, the wire thickness has little effect on the drag coefficient, and when the netting is parallel to the water flow, the drag coefficient of the netting with thicker wire is larger. The test results show that the drag coefficient of the netting is related to the solidity ratio, the wire thickness and the Reynolds number. This test provides a theoretical basis for the design improvement and application of polymer fishing netting in the future.

Key words: polymer knitted netting, solidity ratio, flume test, drag coefficient

摘要: 高分子渔用材料在设施养殖和海洋渔业中的应用越来越广泛,对其水动力特性进行研究十分必要。试验采用不同网目系数和网线粗度的高分子编结试验网片进行水槽试验,倾角从0°变化到90°,设置水流速度从0.3 m/s开始,以0.1 m/s为梯度,逐渐增大至1.3 m/s。为减小尾流和湍流对试验结果的影响,使用流线型框架固定装配。经试验得到以下结果:(1)在网片与水流垂直时,阻力系数有随网目系数增大而增大的趋势,而在网片与水流平行时随网目系数增大而减小。(2)阻力系数有随雷诺数增大而逐渐减少的趋势,网片平面与流体运动方向速度垂直时,阻力系数在1 300<Re<2 000范围内趋于稳定;网片平面与流体运动方向速度平行时,Re>1 500后阻力系数变化不大。(3)阻力系数随着冲角的增大而增大并最终趋于稳定值。(4)升阻力系数比(K)在总体上有随倾角变大而先变大再变小的趋势,K的极值均出现在20°到30°内,最大K值约为0.41。(5)网片与水流垂直时,在1 000<Re<2 000范围内,网线粗度对阻力系数的影响不大;网片与水流平行时,网线较粗的网片,阻力系数更大。试验结果表明,该网片阻力系数与网目系数、网线粗度和雷诺数有关。该试验可为今后高分子渔用网衣的设计改进和应用提供理论依据。

关键词: 高分子编结网片, 网目系数, 水槽试验, 阻力系数