罩网自由沉降过程的数值模拟研究

Numerical simulation on untrammeled settlement process of falling-net

通过集中质量法建立罩网网具的数学模型,对罩网自由沉降过程进行数值模拟研究。模拟结果通过罩网4种配重沉降试验实测数据的验证,并展示了罩网自由沉降过程的空间形状变化。研究发现:1)随沉降进行罩网网口形状变为近似圆形,迎流面较圆钝,背流面存在沿海流方向的突出部;2)4种配重间网口质量点拉力、水动力、沉降速度均存在显著性差异且随配重的增加而增大;3)网口质量点的拉力先骤然增大,之后呈现先变小后增大的波动,最后缓慢增大;网口质量点的水动力、沉降速度先骤然变小,之后呈现先增大后变小的波动,最后缓慢减小;4)研究认为在罩网作业所允许的配重范围内,沉降速度随配重的不断增加而持续增大。

The lumped mass method was adopted to build the mathematical model of falling-net, and the untrammeled settlement process was studied by numerical simulation method. The simulated results which were verified by measured data in settlement test of four different weights show that the change of falling-net space shaped in the untrammeled settlement process. The study shows that： 1 ） the shape of net mouth became approximate circular along with the settlement, obtuse on the side of against the current, and salient along the direction of the current on the other side; 2） there was significant difference in tension, hydrodynamic force and sinking speed of the mass point in the net mouth among four weights and all of them increased with the weight ; 3） the tension of the mass point in the net mouth increased sharply at first, then showed a decrease-increase fluctuation, and increased slowly at last. The hydrodynamic force and sinking speed decreasd sharply at first, then showed an increase-decrease fluctuation, and decreased slowly at last; 4） the study suggests that the sinking speed continues to increase with weight in the allowable weight range of falling-net.