不同排布方式圆形重力式网箱容积保持率的模型试验

Model test on the volumetric maintenance rate of round gravity cage in the different marshalling patterns

以目前使用较多、主尺度为周长50 m、深8 m的HDPE圆形重力式网箱为研究对象,通过在主尺度为90 m×6 m×3 m的试验水池内的模型试验,研究其在不同配重、两种排布方式、不同排布间距条件下网箱的容积保持率变化。结果表明:"一字型"的网箱排布方式时,不同的排布间距对第一只网箱的受流影响不大;第二、第三和第四只网箱由于前一只网箱的减流作用,网箱间距越小,其作用越明显,容积保持率越高。"田字型"的网箱排布方式时,由于并排网箱产生的涡流的影响,第一只和第二只网箱在相同流速下其容积保持率较"一字型"排布方式减小,且网箱排布间距越小,涡流的作用越明显,容积保持率越低。模型网箱的容积保持率均随着配重的增加而增加,高流速下配重的调节作用减弱。根据实验数据以及在实际海上作业情况,建议"一字形"排布、25%间距方式设置网箱,可适当增加迎流第一只网箱的配重,其它网箱建议可采用700 kg配重。

Present paper dealed with the tests concerning the volumetric maintenance rate of round gravity cages in the different marshalling patterns. The HDPE double-pipeline round gravity cages have been used as the cage model, the circumference and depth of each and all were 50 m and 8 m respectively. Test were conducted in the flunk tank with the size of 90 m × 6 m × 3 m. The cubical maintenance rate of the cage has been tested at different balance weights, different marshalling patterns and different marshalling intervals. The results showed that at ＂-＂ shaped model marshalling pattern, the different marshalling interval could slightly influence on the cubical maintenance rates of the 1 st cage, and then from 2nd to 4th cage, the cubical maintenance rate of them would be increased along with the decrease of the marshalling interval because of the flow reduced by the anterior one. At ＂ 田＂ shaped model marshalling pattern, the cubical maintenance rates of the 1st and the 2nd cage were less than those at ＂-＂shaped model marshalling patterns owing to be effected by eddy from the cages arranged side by side, and decreased along with decrease of marshalling intervals. The cubical maintenance rates of all cages would be increased with the increase of the balance weight, but the regulating function of the balance weight would be weakened under the high velocity of the flow. According to the experimental data and actual operating state on the sea, it is herewith suggested to adopt＂ -＂ shaped model marshalling pattern and 25% marshalling interval,the balance weight of the first cage could be suitably increased and 700 kg could be used for the balance weight of the other cages.