| Seine aquaculture is an ecological marine aquaculture model that has been developed in recent years and has developed rapidly.Most of its shallow sea seine aquaculture is laid in the offshore waters.When the waves propagate from the open sea to the offshore,due to the influence of the Submarine topography,the waves will be deformed,refracted,reflected,and even broken.and the wave energy will be consumed greatly,which makes the wave force on the net system become complex.For the purse seine aquaculture,the safety performance of the net clothing system has always attracted much attention,and the safety performance of the net clothing system has a lot to do with the hydrodynamic force it can bear.The research group and other related scholars have studied the hydrodynamic characteristics of the net clothing under the action of pure waves or currents,but the research on the impact of topography changes on the net clothing system has not received enough attention.In this paper,through physical model test,a plank slope is added in the flume to simulate the change conditions of inshore topography.With the help of modern instruments equipment and technology,the influence of wave factors change on the maximum horizontal positive force value of the net clothing system on the slope is studied when the incident wave is a regular wave.The hydrodynamic characteristics of the net clothing system on different slopes and the hydrodynamic characteristics of the net clothing system when the wave breaking against the slope.Based on the wave theory and Morrison's equation,the empirical formula of the maximum force on the net clothing under regular wave action is derivedFor the wave flume test of the net clothing system,according to the test conditions,two different slopes with the same horizontal length and the different vertical height are set,which are large slope(slope ratio 1:7)and small slope(slope ratio 1:15).A custom force-measuring device is used to fix the net clothing and the three-way force-measuring balance At the same time,the amplifier,acquisition instrument and computer are connected to form the entire wave force acquisition system.In addition,the wave height instrument and current meter(ADV)are connected to the computer to collect the test wave height and flow velocity A total of 25 sets of working conditions are designed in the experiment.The wave test is carried out by controlling a single variable.The effects of wave height,wave period,distance along the path,slope,wave breaking and non-breaking on the hydrodynamic characteristics of the net clothing system are discussed.The test results show that:when the wave-steepness or the wave period is determined,the force of the net clothing system increases with the increase of the wave height;when the wave height is determined,it also tends to increase with the increase of the wave period,but it has less influence on the wave height period;in the same wave condition,the wave force of the net clothing system on the large slope is greater than that of the small slope;through the quantitative analysis of the test data,in this test,the maximum stress of the net clothing system on the large slope is about 1.3 times of the maximum stress value at the front of the slope,and it is about 1.1 times about the small when the wave breaking meets the slope,the wave force of the net clothing system is far greater than that of the non-breaking one.In this research,the relation is about 1.9 timesAccording to the wave theory and Morrison equation,combined with dimensional analysis,the influence of wave elements on the stress characteristics of the mesh system is analyzed from theory.The measured velocity is used to calculate the stress of the net clothing system,and the experimental value of the maximum stress of the net clothing system on the slope and in front of the slope is close to the calculated multiple relationship,thus the drag force correction formula in this test is derived:FD=0.9CD?Aux2. |
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