심해 저층트롤망의 수중형상에 관한 모형실험

Abstract

A model experiment using circulation water channel was carried out to investigate the dynamic characteristics of bottom trawl net which can be used in sea mount of North Pacific. Hydrodynamic resistance and shape variation according to the flow velocity and angle of hand rope transformation for net were measured, and experimental value was analyzed as the value of full-scale bottom trawl net. The results summarized are as follows; At the <TEX>$30^{\circ}$</TEX> of angle of hand rope to net, hydrodynamic resistance varied from 0.5kgf to 2.68kgf as the flow velocity increased between 0.31m/s and 0.92m/s, and formula of hydrodynamic resistance for the model net was <TEX>$F_m=3.04\;{\cdot}\;{\upsilon}^{1.53}$</TEX>. At the fixed angle of hand rope, Net height was low and Net width was high according to the increase of flow velocity, and in addition, vertical opening was low and Net width was high by the increase of angle of hand rope at the fixed flow velocity. At the <TEX>$30^{\circ}$</TEX> of angle of hand rope to net, net opening area was <TEX>$0.214m^2$</TEX> as flow velocity was 0.61m/s, and formula of net opening area for the model net was <TEX>$S_m=-0.22{\upsilon}+0.35$</TEX>. At the <TEX>$30^{\circ}$</TEX> of angle of hand rope to net, catch efficiency seemed to be highest as <TEX>$0.319m^3/s$</TEX> of filtering volume at the 0.76m/s(51kt's) of flow velocity. Shape variation of net showed the gradual laminar transform for the variation of flow velocity but there needed some improvements due to the occurrence of shortening at the ahead of wing net.