Research On The Influence Of The Ratio Of Diameter To Depth Of Aquaculture Ponds With Square And Arc Angles On The Characteristics Of The Flow Field And Sewage Collection And Discharge

In recent years,the aquaculture industry has made remarkable achievements under the guidance of the "feeding-oriented" development policy,and occupies a crucial position in the structure of the aquaculture industry.However,the aquaculture industry is inevitably accompanied by thorny problems such as environmental pollution,resource waste,water quality damage and frequent diseases.Therefore,modernization,ecologicalization and intensification are the main development directions of the future aquaculture industry.The industrial recirculating aquaculture system has the advantages of controllable breeding environment,resource saving,and easy centralized treatment of breeding waste.It is in line with the current green,healthy and sustainable breeding goals and is one of the important ways to solve the above problems.The aquaculture tank in the recirculating aquaculture system provides a controllable environment conducive to the growth and reproduction of fish,while suitable hydrodynamic conditions can promote healthy growth of farmed animals and efficient sewage discharge of solid particles(such as residual bait,manure,etc.).Minor changes in the tank structure under specific conditions will also have a greater impact on the hydrodynamic characteristics of the tank.The diameter to depth ratio is an important parameter that affects the hydrodynamic characteristics in aquaculture tanks,and is also closely related to the sewage collection and discharge effect of aquaculture tanks.There are few reports on the influence of the diameter to depth ratio of aquaculture tanks on hydrodynamic characteristics and sewage collection and discharge.Therefore,it is of great significance to study the diameter to depth ratio of aquaculture tank,create a good hydrodynamic environment,smooth discharge of solid particles and water quality control.In order to study the influence of the diameter to depth ratio of the square arc angle aquaculture tank on the flow field and sewage discharge characteristics in the aquaculture tank,this paper established a physical model test system of the single-channel sewage structure aquaculture tank with the size of the actual factory recirculating aquaculture tank reduced.The effects of different diameter to depth ratio(i.e.the ratio of side length of the aquaculture tank to water depth)on the flow field characteristics and sewage discharge effect under the working conditions of parameters such as the layout position of water inlet pipe,daily circulation times of water body and incident angle are carried out.The influence of diameter to depth ratio(2:1?7:1)on the characteristics of the flow field and sewage in the aquaculture tank was systematically analyzed.The main conclusions of this paper are as follows:Influence test of flow field characteristics:(1)The diameter to depth ratio parameter significantly affects the hydrodynamic characteristics of the aquaculture tank.With the increase of diameter depth ratio,the average velocity of water body in the aquaculture tank shows a downward trend.(2)When the ratio of diameter to depth is 3:1?6:1,the aquaculture tank has good hydrodynamic characteristics.In this diameter to depth ratio range,the proportion of low-velocity areas is relatively low,and the water body is relatively uniform,which is conducive to the efficient use of space in the aquaculture tank and the uniform distribution of nutrients.Influence test of sewage discharge characteristics:(1)Proper diameter to depth ratio is the key to improving the sewage discharge efficiency in aquaculture tanks.The smaller the diameter to depth ratio,the higher the sewage discharge efficiency.When the diameter to depth ratio of the square arc angle aquaculture tank is 2:1?3:1,the sewage discharge effect is excellent;when the diameter to depth ratio is 3.5:1?4.5:1,the sewage discharge effect is better;when the diameter-depth ratio is 5:1?7:1,the sewage effect is greatly weakened.(2)Selecting the appropriate diameter to depth ratio working conditions,and according to actual needs,increasing the daily circulation times of the water body,adjusting the layout position and incident angle of the water inlet pipe,will improve the self-purification capacity of the aquaculture tank and improve the discharge efficiency of sewage.(3)The discharge rate of sewage in the aquaculture tank is closely related to the nature of sewage.Within a certain density range,the discharge rate of sewage decreases with the increase of density.The research shows that the range of appropriate diameter to depth ratio parameters corresponding to the flow field performance and sewage discharge performance of different types of aquaculture tanks is also different,and the research results can provide a theoretical basis and reference for the optimal design of the diameter to depth ratio of the factory recirculating square arc angle aquaculture tank,which has certain scientific significance and practical application value,and is conducive to improving the comprehensive performance of the square arc angle aquaculture tank.