进水管设置角度对圆形循环水养殖池自清洗能力的影响

Effect of inlet pipe setting angle on the self-cleaning performance of circular recirculating aquaculture tank

为了提高圆形养殖池的自清洗能力,本研究系统开展了污物汇集试验和流场测量试验。实验针对圆形养殖池双管贴壁进水模式,共设计9个不同的角度工况。利用设置在养殖池正上方的相机记录不同工况下污物的汇集过程,通过分析污物的运动过程以及池内剩余的污物量,量化进水管设置角度对养殖池内污物汇集过程以及自清洗能力的影响。利用PIV技术测量了不同工况下距离池底1、2、10、19 cm(底层、近底层、中层、上层)水层的流场,通过分析流态以及水阻力系数Ct、速度均匀系数DU50等养殖池水动力参数,阐明进水管设置角度对养殖池内污物汇集以及自清洗能力的影响机制。结果显示,进水管设置角度明显影响养殖池的自清洗能力,自清洗能力随着进水管设置角度的增大先增大后减小,在45°~50°工况时养殖池自清洗能力最优;进水管设置角度通过影响底层流速大小和流态影响养殖池的自清洗能力,流速大小决定污物能否起动,流态决定污物能否汇集至出水口。因此,在实际循环水养殖生产中建议将与本研究中类似的养殖池的进水管角度设置为45°~50°,以提高养殖池的自清洗能力,提升循环水养殖系统的综合性能。

In the process of industrial circular recirculating aquaculture,solid wastes will greatly harm the farmed fish.Improving the self-cleaning ability of the recirculating aquaculture tank is an effective way to remove the solid wastes in the recirculating aquaculture tank.The self-cleaning ability of recirculating aquaculture tank refers to the process of automatically collecting solid wastes to the center of the tank by adjusting the water flow in the tank.A series of indoor experiments have been conducted to study the effect of water inlet angle on the self-clean-ing ability of the recirculating aquaculture tank,and the particle imaging velocimetry(PIV)is used to measure the flow field.In the test,a total of 9 cases of different setting angles of the inlet pipe were designed for the circular tank with a symmetrical dual water inlet mode.A camera set directly above the tank is used to record the collec-tion process of the solid wastes under different cases.By analyzing the movement process of the solid wastes and the amount of residual solid wastes in the tank,the effect of the setting angle of the inlet pipe on the solid waste collection process and self-cleaning ability in recirculating aquaculture tank have been quantified.The PIV system was used to measure the flow field in the water layer of 1,2,10,19 cm from the bottom of the tank.By analyzing the flow pattern,resistance coefficient,velocity uniformity coefficient and other hydrodynamic parameters of the recirculating aquaculture tank,the mechanism of the setting angle of the inlet pipe on the solid waste collection process and self-cleaning ability in the recirculating aquaculture tank is clarified.The results show that:the setting angle of the inlet pipe obviously affects the self-cleaning ability of the recirculating aquaculture tank,and the self-cleaning ability firstly increases and then decreases with the increase of the setting angle.The self-cleaning ability of the recirculating aquaculture tank shows good performance under the cases of 45°and 50°;the setting angle of the water inlet pipe affects the self-cleaning ability of the recirculating aquaculture tank by affecting the velocity magnitude and flow pattern in the bottom water layer.The velocity magnitude rate determines whether the solid waste can be picked up,and the flow pattern determines whether the solid waste can be collected to the water out-let.Therefore,in aquaculture practice,it is recommended to set the angle of the inlet pipe of the tank similar to the research in this article to 45°to 50°working condition to improve the self-cleaning ability of the recirculating aquaculture tank and improve the comprehensive performance of circulating aquaculture.