六角形目经编网片和菱形目有结绞捻网片水动力性能比较研究

采用网箱网片模型试验,对水平缩结长度1.7 m×垂直缩结高度为1.7 m的2种不同网片（六角形经编网片RHN,有结菱形绞捻网片KTNDM）,通过改变网片的水平缩结系数（Et分别为0.65、0.707、0.60）,在不同流速下,对网片的阻力性能和运动变化等水动力性能进行了研究。结果如下：（1）网片固定时,菱形目有结绞捻网片的阻力在水平缩结范围（0.60-0.707）内,随着缩结增大而逐渐减小。相同缩结时,六角形目网片阻力在两者中均较大,有结绞捻网片阻力均较小,六角形目网片阻力与缩结关系不明显。2种网片之间的阻力差值随流速的增加而增大。（2）缩结系数对于水平位移和垂直位移的影响随网片的结构差异而不同。相同缩结系数时,六角形目网片的水平和垂直位移均较大。相同网片时,不同缩结系数差异对阻力和运动变化的影响较小。（3）网片的阻力受迎流面积的影响,而网片的水平垂直位移除受阻力影响外还受到流态等因素的影响。

Comparative Study of the Hydrodynamic Performance of the Raschel Hexagonal Net and the Knotted Twisting Diamond Net Used for Sea Cage

Two different nets,the Raschel Hexagonal Net（RHN）,and the Knotted Twisting Net with Diamond Mesh（KTNDM）,each with both horizontal and vertical hanging length of 1.7 m,were studied in this paper by model test in a flume tank.The hydrodynamic performance of the two nets,such as netting resistance characteristics and motion change（horizontal displacement and vertical displacement） were studied based on changing of hanging ratios under different velocity of flow（Et as 0.65,0.707,0.60 respectively）.The results showed that：（1） The resistance of the Net with Diamond Mesh was inversely proportional to the hanging ratios when the net was fixed and with the horizontal hanging range between 0.60 and 0.707. The netting resistance of RHN was the higher that of KTNDM under the same test conditions and was not well correlated with the hanging ratios. The resistance differences between the two nets increase with the increasing flow velocity. （2） The effect of hanging ratios on Horizontal Displacement （HD） and Vertical Displacement （VD） was influenced by the structure of the net. Under the same hanging ratios, the HD and VD of RHN were higher than that of the KTNDM. As for the same net, the effect of hanging ratios on netting resistance and motion change was small. （3） The netting resistance was well correlated with the line area. The HD and VD were not only influenced by netting resistance but also by other factors such as liquid flow.