共查询到18条相似文献，搜索用时 203 毫秒
1.
进径比对方形圆弧角养殖池内流场特性的影响研究 总被引：3，自引：0，他引：3
《渔业现代化》2020,(4)
为研究进径比(参数C/B,射流孔位置到养殖池壁的水平距离C与养殖池短边边长B之比)对单管入流模式下双通道方形圆弧角养殖池系统流场特性的影响,基于计算流体动力学仿真技术,应用Fluent前处理软件Gambit构建三维数值计算模型,采用RNG k-ε湍流模型模拟循环水养殖池内流场。物理模型试验证明,该数值模型能够准确模拟方形圆弧角养殖池系统内的流场,同时提出能量有效利用系数评价养殖池系统的能量有效利用率。结果表明:优化进径比可有效改善养殖池系统内平均流速(a=0.05,P0.000 1)、提高能量有效利用率。研究表明,进径比参数C/B在0.02～0.04区间有利于双通道方形圆弧角养殖池系统获得最佳水动力条件。本研究为工厂化循环水养殖进水管的布设位置提供理论参考。 相似文献
2.
为研究进水系统优化对方形圆弧角养殖池内流场特性的影响,实验运用计算流体动力学仿真技术(CFD)构建方形圆弧角养殖池的三维数值湍流模型,单管进水系统设置在养殖池弧壁的中间位置(以下称弧壁单管),并主要对不同进径比(参数C/B,射流管中心位置到养殖池壁的水平距离C与养殖池短边边长B之比)和不同射流角度对养殖池系统内的流场特性开展研究。结果显示,不同进径比条件下,随射流角度增加养殖池水体平均速度均呈现先增大后减小的趋势,且最优射流角度不同。进径比为0.01且射流角度为45°时,养殖池内部流场平均流速最高。进径比为0.03时,最优射流角度为30°。当C/B=0.05～0.13时且射流角度为25°时,水体平均速度最高且流场均匀性较好。进径比C/B=0.07～0.09、射流角度为25°时,养殖池内部流态总体上优于其他工况。研究表明,养殖池流场特性与进水系统进径比和射流角度密切相关。研究结果可为工厂化循环水养殖进水系统设计和优化养殖池系统的流场特性提供理论依据。 相似文献
3.
《渔业现代化》2021,(3)
为研究养殖池入射流间距对双管射流模式下(射流位置位于圆弧角,射流角度为30°)方形圆弧角养殖系统内流场特性的影响。采用流体动力学仿真技术,通过有限体积法和有限差分法构建三维数值计算模型,选取RNG k-ε湍流模型模拟工厂化循环水养殖池池内流场流动状态。结果显示:通过优化入射流间距可以有效提高养殖池整体流速、流场分布均匀性以及能量有效利用系数,减小入射流的能量损失,提高排污的经济效益。当入射流间距在0.05 m时,养殖池系统能够获得最佳水动力条件,此射流间距下,养殖池整体流速更高,污物移动时的向心趋势更加明显,流场运动状态最有利于养殖池内污物的排出。本研究结果可为方形圆弧角养殖池进水管布设方式提供理论参考。 相似文献
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为改善带有顶、底边舱且低径深比的养殖工船养殖舱内流场特性,以提高水产养殖动物福利与经济效益,提出一种结构优化参数折角比(a/B,a为角壁边长,B为养殖舱壁边长),以评估养殖舱内流场的改善效果。基于计算流体动力学(CFD)仿真技术,研究折角比参数a/B(0～0.4)和进水速度(0.8～1.2 m/s)对养殖舱内流场特性的影响。结果显示：不同进水速度下,养殖舱内流体特性的变化趋势一致;养殖舱水力停留时间一致的条件下,当折角比参数0.25≤a/B≤0.40时,养殖舱内流场均匀性较好,平均流速较原方形养殖舱提高35%,能量有效利用率提高70%;角壁附近低流速区域减少,养殖舱中间排水口区域有明显涡柱形成,有助于提高养殖舱系统的自清洁性能。研究表明,折角比参数a/B控制在0.25～0.40时,有助于提高养殖舱系统的能量有效利用率和养殖空间利用率。研究结果可为养殖工船养殖舱的结构设计和优化提供参考依据。 相似文献
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《渔业现代化》2021,(3)
为改善水产养殖池内的水动力条件,同时兼顾降低工厂化循环水养殖的能源消耗,采用计算流体力学(Computational Fluid Dynamics, CFD)技术,建立对直双管(两个进水管布设于不相邻的两个直壁中间位置)入流的养殖池三维数值计算模型,对不同射流角度的方形圆弧角养殖池内流场特性开展数值模拟。结果显示:射流角度对养殖池内平均流速和流场分布均匀性的影响明显;在同一循环次数设定条件下,当射流角度在0°～10°区间,有利于获得更高的水体流速和更均匀的流场,尤其以射流角度为0°时效果最优,养殖池内流场特性总体上优于其他工况,满足降低养殖能耗与兼顾营造养殖生物所需适宜流场的需求。本研究可为工厂化循环水养殖系统养殖池流场的设计建造提供参考。 相似文献
6.
循环水养殖系统管式射流集污特性试验研究 总被引：1，自引：0，他引：1
工厂化养殖池内的污物聚集效果是养殖池设计建造和运行管理的重要指标,对提升养殖技术和管理水平具有重要意义。针对一种典型的工厂化鱼类养殖池,对边侧管式射流系统驱动下的流场特性和污物聚集效果进行研究,探讨了射流角度、射流流速和循环抽吸方式等因素对养殖池内水体流场特性及污物聚集分布规律的影响。利用手持式ADV流速仪在养殖池内进行布点测量,获得各点流速数值,然后利用MATLAB软件进行流场插值构图,研究养殖池的流场分布特性;污物聚集特性采用图像法进行处理分析。研究表明:管式射流驱动作用下,流速从池心向外呈"V"型变化。在射流角度固定为40°条件下,射流速度越大,池心低流速区域范围越小,污物聚集效果越好。当射流速度达到0.3 m/s时,污物基本聚集于池心;在流速固定的情况下,对污物聚集效果存在一个最佳的射流角度,约为40°。池内循环抽吸模式对流场和污物聚集效果同样有着显著的影响。研究表明,采用底部抽吸时,排污孔附近的径向流速与切向流速均高于边侧抽吸模式,且污物聚集效果明显优于边侧抽吸模式。该研究成果可用于工厂化鱼类养殖池管式射流水力驱动系统的优化设计,在不影响养殖对象生长的前提下,可尽量提高射流流速,最佳射流角度一般为40°左右,并尽量采用底部抽吸模式。 相似文献
7.
工厂化对虾养殖池管式射流集污水力特性 总被引：2，自引：0，他引：2
工厂化养殖池内水体的流场分布特性直接决定了其对残饵、粪便等的排污性能。本实验研究了管式射流驱动模式下,射流角度与射流流速对养殖池内水体流场与污物聚集特性的影响。养殖池流场特性采用点式流速仪进行布点测量,利用MATLAB软件对流场特性进行分析。采用相机采集的养殖池集污效果图像,并利用Photoshop软件与自行开发的不规则图形面积分析软件对图像进行分析。研究表明,流速从池心向外呈"V"型变化,在射流角度固定的情况下,射流速度越大,池心低流速区域越小,污物向池心的聚集效果越好;在流速固定的情况下,存在一个最佳的射流角度,本实验在24 cm/s流速条件下,射流角度为40°时,池内污物聚集效果最优。结论认为在保证养殖对象生长的前提下,可尽量提高射流流速;在24 cm/s流速条件下,最佳射流角度在40°左右。本研究成果可为工厂化养鱼池、养虾池等管式射流水力驱动系统的优化设计提供参考依据。 相似文献
8.
《渔业现代化》2021,(4)
为有效解决水产养殖环境污染、提高水产品品质,本研究构建了一套1.33 hm~2的多营养级池塘养殖中试试验系统,主要包括草鱼养殖区、河蟹养殖区、螺蛳鲢鳙养殖区和水处理设施等。养殖的草鱼、河蟹作为饲料营养的Ⅰ级利用层级,投放的螺蛳、鲢鳙作为Ⅱ级利用层级,种植的沉水植物作为Ⅲ级利用层级,按时打捞水草、螺蛳作为草鱼、河蟹的生物饵料,从而提高饲料营养物质向鱼蟹等主养对象的转化比例。利用计算流体动力学(CFD)软件建立了试验系统水循环过程的1∶1比例计算模型,研究了全域水循环过程和单个草鱼养殖池的流动特性,并开展了水质调控试验,在试验系统内设置14个采样点,对一个养殖周期的水质参数进行监测。结果显示:草鱼养殖池壁附近的水体流度大于轴心区域的水体流速,有利于颗粒废物的沉淀,及时集排污;系统开启运行300 s后,水体在整个系统中的流态趋于稳定,营养物质在系统各个池塘中的分布基本均匀,保证物质能量的高效循环;系统对养殖水体氮、磷的去除效果显著,养殖全程的总氮质量浓度低于5 mg/L,总磷质量浓度低于1 mg/L,符合淡水养殖排放水标准,但对化学需氧量(COD)的控制效果不显著,应进一步改进系统结构,加强系统对有机污染物的处理能力。本研究为多营养级分隔池塘养殖系统的设计提供了参数参考。 相似文献
9.
养殖池是循环水养殖中的关键设施,养殖池内水体的流态则是研究养殖池两相流的基础,并直接决定了养殖池的性能优劣.借助计算流体动力学软件包Fluent,采用标准模型和RNG模型分别对Cornell-type 双通道养殖池进行数值模拟,得到养殖池内水体流场的速度分布.模拟结果表明,水体回转速度大小与养殖池中心的径向距离呈线性增长关系,池中心处速度最小,越远离池中心回转速度越大,靠近池壁处速度达到最大;同时通过实验数据对模拟结果进行了验证,对比结果分析表明,RNG模型比标准模型模拟效果相对较好,模拟结果也基本符合Cornell-type双通道养殖池的运行规律,这为养殖池的优化设计及结构改进提供了新的研究方法和手段. 相似文献
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This study investigated the three-dimensional flow structures in an ellipsoid, closed sea fish cage. The results are presented using computational fluid dynamics (CFD) simulations and experimental measurements. Experimental residence time distribution (RTD) measurement and CFD simulation are the best methods to study the hydrodynamics of inflow systems. Three-dimensional numerical simulations of the flow and transport characteristics of the system were conducted using a Reynolds-averaged Navier-Stokes equation approach and the results were compared to the measurements performed using acoustic Doppler velocimetry techniques. The objective of the investigation was to characterize the flow field generated in an ellipsoid, closed tank. The flow in the enclosed volume is driven by four inlets pipes integrated into the wall of the cage. The focus is on the turbulent structures and undesirable flow patterns that lead to reduced self-cleaning efficiency and a lower quality habitat for the fish through phenomena, such as recirculation zones or low velocity areas. Correlations between CFD and the experimental data confirm the adequate reproduction of hydrodynamic conditions and reinforce the predictive capabilities of numerical models as tools to simulate field scale closed containment systems or to optimize existing and future aquaculture designs. The simulation of aquaculture-like particles demonstrates that almost 100% of particles with a diameter ranging between 1 μm and 3000 μm are removed during a maximum of two hydraulic retention time (HRT) cycles. Smaller particles are removed via the upper-side outlets and larger particles are removed via the bottom outlet. 相似文献
12.
The objective of the work is to improve the design rules of rectangular aquaculture tanks in order to achieve better culture conditions and improve water use efficiency. Particle tracking velocimetry techniques (PTV) are used to evaluate the flow pattern in the tanks. PTV is a non-intrusive experimental method for investigating fluid flows using tracer particles and measuring a full velocity field in a slice of flow. It is useful for analysing the effect of tank geometries and water inlet and outlet emplacements. Different water entry configurations were compared, including single and multiple waterfalls and centred and tangential submerged entries.
The appearance of dead volumes is especially important in configurations with a single entry. Configuration with a single waterfall entry shows a zone of intense mixing around the inlet occupying a semicircular area with a radius around 2.5 times the water depth. A centred submerged entry generates a poor mixing of entering and remaining water, promoting the existence of short-circuiting streams. When multiple waterfalls are used, the distance between them is shown to have a strong influence on the uniformity of the velocity field, increasing noticeably when the distance between inlets is reduced from 3.8 to 2.5 times the water depth. The average velocities in configurations with multiple waterfalls are very low outside the entrance area, facilitating the sedimentation of biosolids (faeces and non-ingested feed) on the tank bottom. The horizontal tangential inlet allows the achievement of higher and more uniform velocities in the tank, making it easy to prevent the sedimentation of biosolids. 相似文献
13.
研究人工鱼礁在波流作用下的水动力特性,对于人工鱼礁的设计具有重要的意义。基于有限体积法,采用边界造波,利用自由表面捕捉法(VOF)捕捉自由水面,建立了可以分别模拟纯波、均匀流以及波流共同作用下人工鱼礁水动力特性的多功能三维数值波流水槽。基于该数值模型对不同波流工况作用下圆柱型镂空人工鱼礁水动力特性进行数值模拟,并与物理模型试验结果进行比较。结果显示,人工鱼礁数值模拟受力与模型试验结果吻合良好,人工鱼礁所受的波流力最大值随着波高、周期和水流流速的增大而增大;人工鱼礁处于波流场波峰正下方时,背涡流的面积随着水流流速的增大而增大,随着波高、周期增大而减小。对单独均匀流作用、单独波浪作用和波流联合作用下人工鱼礁的水动力特性对比研究表明,人工鱼礁所受的最大波流力比最大波浪力、水流力都大,波流联合作用下的流场效应最显著,在礁体的后部形成了较大规模的漩涡结构。 相似文献
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为给养殖池的池型选择与设计提供理论依据,在相同的池体尺寸、进水速度和池底出水比例条件下,针对Cornell和Waterline两种经典双通道圆形养殖池,对其速度流场进行了计算流体动力学(CFD)仿真分析。仿真应用Ansys 15.0软件中的Fluent模块,采用RNG k-ε湍流模型对两种池型的内部速度流场进行了数值模拟,分析其流场特性并进行对比。结果显示:两种池型的水流速度向池中心方向在很短距离内随着径向距离的减少而急速增大,当达到某一径向距离时,速度达到最大值,然后速度随着径向距离的减小而减小,在池子中心轴线或附近处速度降到最小;在纵向上,与池心相同水平距离处的水体流转速度则随着高度增加而减小;在池底出水分流比小于10%时,Cornell池池底自清洁能力、池子整体流场均匀性均比Waterline池差。仿真结果从理论上验证了两种池型底流比例的经验设计值在10%以上。 相似文献
15.
Qingchang Xu Liuyi Huang Fenfang Zhao Xinxin Wang Yanli Tang Zhenlin Liang Rong Wan Peng Sun Changdong Liu 《Fisheries Science》2017,83(2):181-190
The hydrodynamic performance of the rectangular V-type otter board is studied by two kinds of numerical simulation methods. The model tests are conducted in the flume tank as well as a comparison to the numerical results. It is found that the CFX analysis is better at simulating the forces, especially for predicting the maximum lift coefficient and the maximum lift-drag ratio. On the other hand the FLUENT analysis is better at simulating the velocity field. The full-scale otter board is then studied by means of CFX simulation to investigate their hydrodynamic performance. The results show that the otter board will be optimized when the aspect ratio is set to 0.490 with a dihedral angle (Г) of 17°. It is confirmed that the numerical simulation is a powerful tool in studying the hydrodynamic characteristics of the otter board and is useful in designing and optimizing otter boards. 相似文献
16.
随着人口与经济的发展,水产养殖业在世界范围内迅速兴起,集约型工厂化循环水养殖因其高密度、低污染、高效率等独特的优势,契合水产养殖业绿色发展理念,已成为水产养殖转型升级的重要方向之一。水作为循环水养殖系统中重要的环境因子,其流态能够直接影响鱼类的生长及福利,同样,鱼类存在及运动也会影响到系统流态的构建。本文综合分析了循环水养殖系统中流场条件对不同鱼类生长发育及福利的影响,鱼类及其运动行为对养殖池内水动力条件及性能的影响,以及鱼类对养殖池内流场流态、水体混合等的影响。将研究鱼类运动对流场特性的影响方法主要归纳为实测法和数值研究,通过对比分析2种方法的优点和不足之处,并结合当前循环水养殖产业系统构建中的问题提出针对性方法建议,旨在为系统中水动力条件的设计拓展思路,促进循环水养殖产业流态构建向“鱼”与“水”兼顾的方向发展。 相似文献
17.
Marine aquaculture is widely distributed in coastal areas. The aquaculture farms generate drag resistance to fluid motion and alter ambient hydrodynamics. Meanwhile, aquacultural structures are subjected to complex flow conditions including waves and currents. With the expansion to more open areas with severe flow field conditions, marine aquacultural structures face greater challenges and risks of damage. Culture unit is an important component of aquacultural structures and shows flexibility in both field observations and laboratory measurements. Underestimating or overestimating the drag resistance of culture units under the action of fluid flow can lead to damage risks or overdesign of the structure. A dynamic model is developed to estimate the deflection of flexible culture units and is incorporated into an aquacultural structure numerical model in this paper. Critical factors for safety as well as routine operation of aquacultural structures are considered including structural responses and mooring line forces. A suspended mussel long line system is taken as an example, and the results show that the calculated value (9.2 kN) of the maximum tension of the north mooring line is in good agreement with the measured data (9.8 kN) under the action of tide flow. The influence of different flow field parameters on structural dynamic responses is investigated. The numerical results indicate that decreasing wave height can reduce maximum mooring line tension and longitudinal and vertical motion amplitude of the main line. The maximum tension of the mooring line generally decreases with the increase of the angle between the main line and the inflow direction under the action of waves and tide flows. In structural design, the arrangement angle of structures can be determined according to the force calculation of mooring lines based on the numerical model. The spacing of culture units and the distance between adjacent long lines can be determined by referring to the motion calculation of structures to avoid damage due to intertwinement of structural components. 相似文献
18.
网板是单拖网中实现网具扩张的重要属具,其稳定状态直接决定拖网网口扩张程度,进而影响渔获效率和经济效益。该研究以立式双曲面网板为研究对象,利用水槽模型试验和数值模拟(Computational fluid dynamics,CFD)探究立式双曲面网板在不同倾斜状态(内、外倾斜,前、后倾斜)和冲角下的水动力性能变化,并对网板周围流场和表面压力进行可视化。结果显示:1)模型试验和数值模拟的网板升力系数均在倾角为0°,冲角为25°时达到最大值,分别为1.69和1.88;而两者的阻力系数均随倾角增大逐渐减小。2)模型试验和数值模拟的升阻比均随倾角增大逐渐减小;当内倾角为5°时,两者的升阻比均达到最大,分别为3.27和3.69。3)压力中心系数Cpb随倾角变化基本保持不变;但当网板处于前倾状态时,Cpc随倾角增大而增加;而网板处于后倾状态时,Cpc随倾角增大逐渐减小。4)CFD结果显示,网板中心面后部旋涡随倾角增大逐渐减小;当网板处于内、外倾状态时,前端流速衰减区随倾角增大逐渐增加;但当网板处于前、后倾状态时,衰减区随倾角增大逐渐减小;网板处于前倾状态时,压力中心随倾角增大逐渐向网板上端翼弦移动,网板处于后倾状态时则出现相反结果。研究结果可为今后研究网板稳定性和合理使用及调整网板提供科学参考。 相似文献