基于STAR-CCM+的圆形循环水养殖池进水管布设位置优化

为探究圆形循环水养殖池进水管布设位置对池内的流场分布以及残饵粪便等固体颗粒物排出的影响。该研究基于计算流体动力学（Computational Fluid Dynamics,CFD）技术,采用STAR-CCM+软件系统地模拟进水管在常见布设角度（θ=0°、45°）,不同布设位置（d=0、1/8 r、1/4 r、3/8 r、1/2 r,d为射流管与池壁的距离,r为养殖池半径）工况下,养殖池内的流场分布特性和固体颗粒物的运动特性,并以固体颗粒物的排出率为主要性能指标,对进水管布设位置进行优化分析。监测了距离池底2、16.5、31 cm（底层、中层、顶层）水层的流场分布特性并利用固-液-气三相流模型详细地模拟了固体颗粒物在养殖池内的运动和汇集过程。结果表明：在水力停留时间为20 min下,进水管设置位置明显影响固体颗粒物的排出率,θ=0°时,当布设距离设置为d=0时,固体颗粒物的排出率最低,其余布设距离工况下,排出率均较高（＞90%）且相差不大,在d=3/8 r时取得最大值94.8%;θ=45°时,当布设距离设置为d=1/2 r时,固体颗粒物的排出率最低,其余布设距离工况下,排出率均较高（＞90%）且相差不大,在d=0时取得最大值94.3%。因此当进水管布设角度θ=0°时,建议不要贴近养殖池边壁;当进水管布设角度θ=45°时,建议距离养殖池边壁不要超过半径的1/2。研究结果可为优化工厂化圆形循环水养殖池的进水管布设距离提供参考,提升循环水养殖的综合性能。

Optimization of the inlet pipe layout of circular recirculating water aquaculture tank based on STAR-CCM+

Abstract: A land surface on Earth is an important space carrier for human survival, social and economic activities, as well as ecological civilization. The function pattern of land space has undergone some dramatic changes, with the rapid development of urbanization in recent years. Therefore, it is necessary to promote the orderly, moderate, and sustainable utilization of land space. Taking the county unit of Henan Province in China as an example, this study aims to explore the spatial-temporal evolution characteristics and influence factors of "production-living-ecological" functions (PLEFs) using the theoretical analysis. A PLEFs index system was also constructed to identify the land space pattern in 2000, 2006, 2012, and 2018 from the perspective of spatial function. A principal component analysis was then made to diagnose the impact factors and mechanism of PLEFs evolution, with an emphasis on the theoretical guidance and scientific basis for the regional sustainable development. The results show that: 1) There were different degrees of growth for the PLEFs in the study area, when the entropy weight and GIS were performed on the spatial pattern characteristics and evolution of PLEFs in 2000, 2006, 2012, and 2018. More importantly, the PLEFs presented the regional differentiation in the land space. There was also a significant spatial gradient difference in production function. The living function was gradually weakened from the municipal area to the outside urban, where the ecological function showed a gradient change of "mountain hilly area > plain area > municipal area". 2) The evolution of PLEFs in the study area changed significantly from 2000 to 2018. Specifically, 24.39% of the production function was significantly weakened, 86.99% of the living function level was improved, whereas, the ecological function developed steadily, leading to the fewer weakened areas. 3) The principal component analysis indicated that food security, social stability, and ecological maintenance were the important factors affecting the evolution of PLEFs in the study area. The basic factors also included economic development and ecological bearing. As such, the different factors needed to form a common thrust for the healthy development of PLEFs. The major findings were summarized as follows: 1) The PLEFs in the study area presented significant characteristics of spatial differentiation and evolution. There was a synergistic relationship of the production and life function in space, whereas, there was a fewer overlapping in the spatial distribution of production, living and ecological function. The PLEFs can be widely expected to mutually intersect and coexist from the perspective of time and space. 2) There was a different evolution in the production, living and ecological functions for the various counties. A differentiation strategy also needed to address each county, according to the specific functional development, in order to optimize the spatial resources for the highly comprehensive function level. In sum, it is a high demand for the tradeoff between development and ecology for the decision-making on the development policies of differentiated regional function. Meanwhile, the finding can offer a strong reference to formulate the spatial planning for sustainable utilization in the regions.