Deformation and flow resistance characteristics of model net cages according to shapes and arrangements of sinkers

발돌의 형상 및 배치 방법의 변화에 따른 모형 가두리 그물의 변형 및 유수저항 특성

  • 김상국 (서해어업지도사무소) ;
  • 양경욱 (전남대학교 해양기술학부) ;
  • 김대안 (전남대학교 해양기술학부) ;
  • 김태호 (전남대학교 해양기술학부)
  • Published : 2007.08.31


The objective of this study was to investigate the optimal shapes and arrangements of sinkers attached to net cages to prevent their deformation in a current. A series of model experiments were conducted in a circulating water channel, using 5 different types of sinker(high-weighted ball, low-weighted ball, columntype, egg-shaped and iron bar-framed) and 2 types of square net cage constructed from both Nylon Raschel netting and Nylon knotted netting, on a 1/20th scale. The deflection of the model nets against the flow was smallest with the iron bar-framed weight compared to the other four types of sinker. It was expected that the optimal shapes of sinkers would be either the ball or egg-shape; however, iron bar-framed weight actually had larger drag forces. The dispersed deployment of sinkers on the bottom frames of model net cages performed better with relatively slow flows, while the concentrated deployment at 4 corners functioned better with relatively fast flows, in preventing the nets from becoming severely deformed. The deformation of the net cages was larger for the Nylon knotted netting than the Nylon Raschel netting. With respect to flow resistance, the Nylon Raschel netting, rather than the Nylon knotted netting, was more suitable for construction of net cages.


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