摘要
通过分析与试验相结合的方法对重力相似准则在网衣试验中的适用性进行研究。试验以在国内应用较广的田内相似准则作为参照,分析讨论了两种相似准则的异同,推导得出了重力相似准则结合大小尺度比在网衣模型设计中的质量校正公式及刚度校正公式。并据此按照两种相似准则,设计了包括网衣、底杆和沉子系统的两套模型,模型上端固定于设置了受力传感器的刚性直杆上。试验在纯流条件下进行,分别设置5组流速,试验水深0 8m。各组流速重复试验3次,受力由固定于刚性直杆上的传感器测量获得,网衣的变形则通过系缚在网衣上的二极管的坐标确定。在进行受力分析时,由于两相似准则的受力比尺不同,因此必须将模型受力按照对应比尺统一转换为原型值,同时利用受力与流速的回归关系式将模型受力校正为同一流速下的数值然后再进行比较。试验结果表明,相同流速条件下,两种相似准则的模型受力及变形总体上吻合较好,说明重力相似准则在网衣试验中采用质量校正及刚度修正后同样能够得到令人满意的结果,而且试验中模型的大尺度比达到1∶20,这无疑为涉及波浪问题的深水网箱模型试验的设计提供了保障,从而避免了田内相似准则在深水网箱试验研究中应用的局限性。
The deep water sea cage engineering developed very fast,but the research on its hydrodynamic characteristics is relatively weak.Model experiments are important methods for such study, but the main difficulty is how to give a reasonable simulation criteria for the model test of fishing net.Many researchers proposed different methods to solve this problem when dealing with sea cage experiments.Based on Morison Equation together with consideration on the change of drag force coefficient, Fredriksson (2001) in his study proposed a method to model the fishing net by compensating the error of twine projected areas.But the relationship between drag force coefficient and Reynold number has to be set up firstly through experiments.While the experiment results,in great sense,depend on the conditions of the model configuration,the components and material used,Phe sea cage model without any modification on net mass and twine projected area for the difficulties in modelling the net system reported in one of his research papers.In trawl net experiments, several simulation criteria of net models were proposed by various scholars.The familiar criteria are Dickson criteria,Christensen criteria and Tauti criteria.Dickson criteria,which is used popularly in west Europe and Christensen criteria,is often used in America,and Tauti criteria was worked out by Professor Tauti and is used frequently in Japan and China.But for sea cage experiments,all these simulation criteria encounter different problems and have different restricts.The main difficulty of Tauti criteria applied in sea cage experiments is the large scale of particle velocities which will make the wave conditions difficult or even impossible to implement.So once more we paid our attention to the Froude law.This paper focused on the feasibility of the application of Froude law for fishing nets model design and during the experiments the Tauti law was selected for comparison.Through this analysis,the differences were found out between Froude law and Tauti law and the mass
出处
《中国水产科学》
CAS
CSCD
北大核心
2005年第2期179-187,共9页
Journal of Fishery Sciences of China
基金
国家"863"高技术研究发展项目(2001AA623010)
国家自然科学基金资助项目(50279002)
辽宁省教育厅高教科研项目基金(20102138).
关键词
深水网箱
网衣
模型试验
相似准则
deep water sea cage
fishing net
model test
simulation criteria
