管式射流驱动下的养殖池集污水动力学特性研究

发布时间：2018-07-14 21:23

【摘要】：工厂化养殖是我国设施渔业的重要领域,是一种现代化、高密度、集约化的养殖模式,在养殖环境污染严重、水资源匮乏的情况下,越来越受到养殖企业的重视并不断发展起来,是目前水产养殖业发展的主要趋势。工厂化养殖多采用循环水养殖模式,即通过将养殖废水进行物理过滤、生物过滤等步骤,在保证水质条件的情况下,实现养殖用水循环利用,实现0排放0污染的高效养殖模式。循环水养殖模式的核心是水处理技术。目前,针对养殖池内水质处理主要包括固体废弃物的去除、可溶性污物的去除以及水体消毒与增氧。而固体废弃物作为养殖水质的首要污染因素,如何及时高效的清除是改善水质条件的重要手段。本文利用试验与数模相结合的方式对工厂化对虾养殖池及鱼类养殖池的集排污水力特性进行探究,研究不同射流角度与射流流速条件下,养殖池的流场分布特性与污物聚集特性,为工厂化循环水养殖池的工程设计提供参考依据。本文主要结论如下:(1)利用试验方法探究了对虾养殖池在不同射流角度(0°、10°、20°、30°、40°、50°)与射流流速(10cm/s、15cm/s、20cm/s、22cm/s、24cm/s、28cm/s)的污物聚集特性及流场分布特性。研究发现边侧射流驱动下,射流角度在40°以内时,方形圆切角养殖池内断面流速呈“V”字形分布,接近池心附近的流速较大,向外先降低,然后再增大。但当射流角度超过40°时,根据集污效果可推知,流场将较为凌乱。养殖池的表层流态和底层流态亦存在一定差异。表层流场高流速区主要出现在横竖断面贴近池壁处,而底层流场的高流速区主要出现在射流口及其下游弯段区间内。方形圆切角养殖池的集污效果受射流角度和射流速度影响。研究发现,射流角度为40°时,最有利于池内污物聚集。射流流速越大,集污效果越好。(2)利用数值模拟的方法探究了养殖池内不同切面上的速度分布规律,径向流速与切向流速的分布规律,不同射流角度α(0°、10°、20°、30°、40°、50°)与射流流速u(10cm/s、15cm/s、20cm/s、22cm/s、24cm/s、28cm/s)对养殖池内流场分布的影响。研究表明:流速总体分布随着纵深距离的增大而减小,底层流场由于池底摩擦力的影响,总体流速最小。各深度的流速呈中间小外围大的分布特点,池心附近纵向速度明显。各深度平面切向速度分布整体呈相对对称的“M”分布,有外围大而中间小的特点,径向流速分布并无明显规律,但对于分析工厂化养殖池池底的集排污特性具有重要意义。随着射流流速u的增大,表层流场与底层流场流速增大明显,且随着流速增大池内水体回转效果变优。射流角度α对流场影响显著,射流角度α为0°时,池内流速整体较小,且池内水体回转效果较差。随着射流角度的增大,流场整体回转效果变优、整体流速变大,到达40°时效果最好,而后随着角度增大,效果变差。(3)利用试验手段研究了鱼类养殖池集污水动力特性,主要探讨了射流流速(0.2 m/s、0.3m/s、0.4m/s、0.5m/s、0.6m/s、0.7m/s)、射流角度(0°、10°、20°、30°、40°、50°)以及抽吸方式(底部抽吸模式、边侧抽吸模式)的影响。结合射流流速试验、射流角度试验与抽吸方式试验,对管式射流集污特性进行研究,综合考虑各种因素,我们建议循环水养殖系统中的池内集污模式,可设定为底部抽吸模式、边侧的射流管角度最优约40°、射流流速应不小于0.3m/s。对于污物颗粒较大、粘性较强的情况,可增大射流流速获得预期的效果,具体流速大小可通过专项研究确定。
[Abstract]:Factory farming is an important field of facilities fishery in China. It is a modern, high density and intensive culture mode. Under the condition of serious pollution and lack of water resources, more and more attention and continuous development of aquaculture enterprises, which is the main trend of the development of aquaculture industry. The aquaculture model, namely, through the physical filtration of the aquaculture wastewater, biological filtration and other steps to ensure the water quality conditions, to realize the recycling of aquaculture water and realize the high efficiency culture mode of 0 emission and 0 pollution. The core of the aquaculture model is water treatment technology. At present, the water treatment in the aquaculture pool mainly includes solid waste. Removal of the soluble contaminants, water disinfection and oxygen increasing, and solid waste as the primary pollution factor of aquaculture water quality, how to improve the water quality in time is an important means to improve the water quality conditions. Under the conditions of different jet angles and fluidic flow velocity, the distribution characteristics of the flow field and the characteristics of dirt aggregation are studied. The main conclusions are as follows: (1) the experimental method is used to explore the angle of the shrimp culture pool at different angles (0, 10, 20, 30, 40, 50). With the jet flow velocity (10cm/s, 15cm/s, 20cm/s, 22cm/s, 24cm/s, 28cm/s), the characteristics and distribution characteristics of the flow field are found. It is found that the flow velocity of the square circular cutting pond is "V" shaped when the angle of the jet is within 40 degrees, and the flow velocity near the pool center is larger and then decreases first and then increases. When the jet angle exceeds 40 degrees, the flow field will be more messy according to the effect of the pollution. The surface flow pattern and the bottom flow pattern of the aquaculture pool are also different. The high velocity area of the surface flow field is mainly in the vertical section near the pool wall, and the high velocity region of the bottom flow field is mainly in the jet port and its downstream section. The effect of water jet angle and jet velocity on the angle of the aquaculture pond is affected by the jet angle and the jet velocity. It is found that when the angle of the jet is 40 degrees, it is the most beneficial to the accumulation of dirt in the pool. The greater the flow velocity of the jet, the better the effect of the pollution. (2) the distribution law of the velocity and the distribution of the radial velocity and tangent velocity in the different sections of the aquaculture pool are explored by numerical simulation. The effect of different jet angles (0, 10, 20, 30, 40, 50) and the flow velocity u (10cm/s, 15cm/s, 20cm/s, 22cm/s, 24cm/s, 28cm/s) on the flow field distribution in the aquaculture pool. The study shows that the overall velocity distribution decreases with the increase of the depth of the depth, and the overall flow velocity is minimum because of the influence of the bottom friction of the pool. The flow velocity at each depth is present. The longitudinal velocity in the center of the pool is obvious. The distribution of the plane tangential velocity distribution of each depth is relatively symmetrical "M" distribution, which has the characteristics of large periphery and small middle, and there is no obvious law of the radial velocity distribution, but it is of great significance for the analysis of the discharge characteristics of the bottom of the pond. With the increase of speed u, the surface flow field and the flow velocity in the bottom flow field increase obviously, and with the flow velocity increasing, the effect of water rotation in the pool becomes better. The jet angle alpha has a significant influence on the flow field. When the angle of the jet is 0 degrees, the flow velocity in the pool is smaller and the water rotation in the pool is poor. With the increase of the jet angle, the overall flow rate of the flow field becomes better and the overall flow is changed. The effect is best when the speed reaches 40 degrees, and the effect becomes worse with the angle increasing. (3) the hydrodynamic characteristics of the fish culture pool are studied by means of test. The jet flow velocity (0.2 m/s, 0.3m/s, 0.4m/s, 0.5m/s, 0.6m/s, 0.7m/s), the jet angle (0, 10, 20, 30, 40, 50) and the suction mode (bottom suction mode, side side) Combined with the jet flow velocity test, the jet angle test and the suction test, the fouling characteristics of the tube jets are studied. Considering the various factors, we suggest that the pool collecting mode in the circulating water aquaculture system can be set as the bottom suction mode, the angle of the jet pipe at the side side is about 40 degrees, and the jet flow velocity should not. Less than 0.3m/s., for larger particles and stronger viscosity, the jet velocity can be increased to achieve the desired effect. The specific velocity can be determined by special research.
【学位授予单位】：浙江海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X714

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