黄河下游引黄灌区水沙调控模式及其特点分析

黄河挟带大量泥沙,沿岸地区进行引水灌溉不能忽略引入泥沙的处理问题。自20世纪50年代黄河下游发展引黄灌溉事业以来,目前不同灌区已基本形成适宜自身地理特点和灌溉需求的引水输水类型和入渠泥沙处理方式。本文根据引黄灌区所处河道位置和地域条件,结合灌区灌溉类型和泥沙处理方式,归纳提出了4种黄河下游引黄灌区水沙调控模式,即,沉沙输水模式、输水沉沙模式、分水滞沙模式和输水输沙模式;根据不同水沙调控模式的形成条件、调控效果和存在的水沙问题,分析了适合不同水沙调控模式的输水输沙关键技术和重点调控目标,分别为沉粗排细调控、远距离输沙调控、分沙入支渠调控和泥沙入田调控;泥沙远距离分散输送技术是实现灌区水沙资源优化配置的重点。     

含沉水植物河道水流流速特性研究

在梯形平底水槽中,用塑料草模拟了沉水植物对水流的影响。结果表明：（1）流速不同、相对植物高度不同的情况下,植物对流速的影响是不同的;（2）含沉水植物的水流垂向流速分布曲线存在一条流速分界线,在其上部流速变大,下部流速变小,流速分界线在植物冠层以上,在相对水深h／H=0．3附近;（3）两株植物叶片之间是否有交叉重叠对水流的阻碍作用是有区别的;有交叉重叠时会额外增加水流阻力;在流速分界线以下,叶片有交叉重叠时流速减小幅度较大。     

河流生态等级划分

我国目前没有河流生态等级的划分标准,通过借鉴国外标准,根据河道线和水流状况、河底、水-岸的交错状况以及河道宽度的多样性、河堤、木本植物5个参数,将我国的河流划分为7个生态等级.     

水电站尾水管隔墩结构与水力 联合优化研究

采用Girimaji非线性紊流模型和Willam-Warnke五参数破坏模型分别模拟弯肘形尾水管水流状态和混凝土材料,并使用APDL语言编制了尾水管隔墩的结构和水力联合优化程序。使用该程序对一河床式水电站尾水管技术改造进行分析,得到了隔墩下移的较优值,为工程设计提供了可靠的数值依据。     

上海洋山港区一期工程潮流模型试验研究

通过潮流水工模型试验 ,模拟洋山港区一期工程方案实施前后 ,港池和航道流速变化特征、水流流态、港区通道潮流变化 ,并估算通道水域水深变化 ,为优化工程方案和设计提供科学依据     

入湖浅水三角洲形成过程实验模拟分析

本文基于自然模型法,对入湖浅水三角洲的形成发展过程进行实验模拟,从河型和流场变化的角度,分析其河道演变过程规律。通过改变上游来沙和下游水位,研究不同边界条件对三角洲形成过程中河道摆动及河型发育的影响。实验结果表明:(1)河槽在顺直、分汊及无河槽的形态间交替演变,下游淤积的河坝会导致地形抬高、反水压力以及溯源淤积现象,促进河道发生周期性横向摆动。(2)三角洲表面流场形态及流速大小随河型变化,且与演变阶段有关。(3)上游多沙和下游高水位,都能使河型周期历时变短,主流摆动角度变大,摆动点位置向上游移动,较多来沙可以使河道形态由鸟足状向辐射状发育。在这一演化过程中,来沙影响占主导而水位影响居次要,水位变化条件不会从根本上改变河道形态的类型。     

某立式轴流泵 CFD 计算与模型试验性能比较分析

针对宣州区某立式轴流泵站水泵装置进行分析,验证水泵设计选型的科学性、合理性,尽量减少和避免如伴随冲击、二次流、汽蚀等有害物理现象,防止影响机组的安全运行。设计中采用 CFD 技术对立式轴流泵装置全流道进行了数值模拟计算,并针对进水流道、泵段、出水流道的内部流态进行了分析判断应用,从而得出立式轴流泵全工况外特性。结合水泵装置模型试验得到水泵试验外特性数据,对比试运行参数,验证了水泵基本性能。结果表明 CFD 计算能初步快速的判断避免不利流态,试运行的工况点水泵性能与 CFD 计算和模型试验结果较相近。因此,对大中型立式轴流泵站同时进行 CFD 计算和装置模型试验是必要的,均对水泵的性能可做出比较准确的判断。     

入汇主河的泥石流龙头运动机理研究

作者基于野外观测资料和模型试验，提出了泥石流与主河交汇的两种模式，即：有上下分层交汇和无明显分层的潜入式交汇。建立了潜入式交汇的泥石流龙头运动方程，并讨论了模型参数的取值。计算结果得到以下结论：当主河水流费劳德数比较小(Fr＜0.35)时，入汇主河泥石流龙头在主河的运动速度近似以线性减速，且与试验值吻合较好；混合流粘滞系数和绕流系数对龙头运动速度影响较大；泥砂沉降速度对龙头内部体积比浓度有显著影响。     

Reach‐scale interactions between aquatic plants and physical habitat: River Frome,Dorset

Substrate and flow velocity are two key physical factors influencing the distribution of aquatic plants. These two controls are closely related and reflect interactions between flow regime, quantity and calibre of sediment supplied to and bounding river channels, and channel dimensions. Seasonal growth of aquatic plants has important impacts upon flow resistance, flow velocities and sediment dynamics. This paper focuses upon the reach scale and the aggregate impact of the seasonal growth of aquatic plants on the meso‐habitat characteristics of chalk rivers. It provides a contribution to the broader literature by illustrating how submerged and emergent macrophytes interact with one another at the reach scale to control flow patterns and the retention of fine sediment. The research was conducted within the River Frome, Dorset, UK. Four sets of observations from 2004 of the seasonal growth of aquatic plants, flow velocity behaviour and the storage of fine sediment are presented. Aggregate velocity behaviour over the four observation periods is classified using agglomerative, hierarchical cluster analysis. The spatial arrangement of patches exhibiting different aggregate velocity behaviour are explored and the degree to which velocity behaviour can be attributed to physical characteristics of patches and the growth of aquatic plants is discussed. Conclusions include: (i) patterns of aggregate velocity behaviour within reaches are strongly influenced by macrophyte growth; (ii) average fine sediment deposition is higher around emergents such as Sparganium erectum than submerged plants such as Ranunculus penicillatus subsp. pseudofluitans; (iii) complementary flow patterns evolve across the river channel as aquatic macrophytes grow and it appears that this allows marginal emergents to scavenge fine sediment from faster flow velocity threads that become diverted towards the channel edges. (iv) These processes are important for mesohabitat evolution and maintenance, and they also contribute to patterns of bank erosion and aggradation. Copyright © 2006 John Wiley & Sons, Ltd.     

3-D hybrid LES-RANS model for simulation of open-channel T-diversion flows

The study of flow diversions in open channels plays an important practical role in the design and management of open-channel networks for irrigation or drainage.To accurately predict the mean flow and turbulence characteristics of open-channel dividing flows,a hybrid LES-RANS model,which combines the large eddy simulation (LES) model with the Reynolds-averaged Navier-Stokes (RANS) model,is proposed in the present study.The unsteady RANS model was used to simulate the upstream and downstream regions of a main channel,as well as the downstream region of a branch channel.The LES model was used to simulate the channel diversion region,where turbulent flow characteristics ate complicated.Isotropic velocity fluctuations were added at the inflow interface of the LES region to trigger the generation of resolved turbulence.A method based on the virtual body force is proposed to impose Reynolds-averaged velocity fields near the outlet of the LES region in order to take downstream flow effects computed by the RANS model into account and dissipate the excessive turbulent fluctuations.This hybrid approach saves computational effort and makes it easier to properly specify inlet and outlet boundary conditions.Comparison between computational results and experimental data indicates that this relatively new modeling approach can accurately predict open-channel T-diversion flows.     

水流移床力及河道运动力学的初步探讨

本文首次提出了水流移床力和河道运动力学的概念，并建立了水流移床力与流量脉动强度的关系。水流挟沙力是水流挟带泥沙通过河道的能力，而移床力则是水流改造河道的能力。非恒定流输沙使水流具有移床力，因而造成河道运动。研究发现，流量脉动强度愈大，移床力也愈大。不同频率的脉动对移床力有不同的贡献。在缺少河道实测运动资料的情况下，可以利用流量脉动能谱算出修正系数k推算实际水流移床力。由移床力与流量脉动的关系可以推论，水流脉动强度愈大，河道愈不稳定。利用水流移床力公式，可以计算和预测河道运动的速度和距离。     

一种简洁有效的河道平面二维流动数值模型

本文提出了一种简洁有效的河道平面二维流动数值模型。模型采用跟踪河道中心线走向的正交曲线坐标系，曲线网格可用代数方法直接生成。这种河道正交曲线网格较好地适合了河流的形态特征及流动特性，模型基于显式有限差分，利用水面回算消除不稳定性。并使模型在空间和时间上均达到二阶精度。模型采用显式非恒定流渐近迭代法计算河流恒定流场，为了有效地抑制非线性不稳定性发展，二维模型初值由准二维计算结果提供。本文针对弯道水槽试验成果。多体绕流，边池回流和天然山区河流情况，对数值模型进行了测试和验证。结果表明，模型具有较强的模拟复杂流态的能力。     

Fluid speed variability and the importance to managing fish habitat in rivers

To properly manage streams for fish habitat it is necessary to move beyond standard evaluations and the acceptance of relationships between variables that are derived either from rivers of much greater scale or those which are based on time-averaged conditions. Clearly, the relationship between moving fluid and channel boundary is the most important in smaller streams that are used as habitat by fish, as variations in speed patterns causing erosion or sedimentation of the bed will determine the success of spawning activity. To this end, an evaluation of fluid speed profiles is presented using field data collected from spawning streams in Ontario, Canada. The data have been subjected to an interpolation algorithm, minimum curvature, to deliver a more accurate view of fluid speed patterns. The results show that fluid speed patterns vary completely within the same cross-section under different flow regimes, even when the mean depth and mean speed of the flow are virtually unchanged, and that mean speed depiction of flow is inaccurate when considering particle transport/deposition. A comparison of data collection practices is presented which shows that flow measurement from the common 60% of the depth at mid-channel produces large errors in speed prediction on moving towards the bed and surface of the channel. Errors in the prediction of near-bed fluid speeds can result in the entrainment of particles within the preferred spawning range of salmonids, which was not predicted through the use of mean fluid speed for the cross-section or through the less intense data collection technique. The minimum curvature technique of data interpolation is shown to be an accurate method for visualizing fluid speed patterns.     

赣江象山枢纽一期临时航道通航水流数值模拟应用研究

赣江主支象山枢纽为通航河流枢纽,工程施工期妥善处理船舶通航问题尤为重要,应结合工程分期施工方案,提出对应的通航方案.一期工程施工由临时航道通航,二期工程施工由船闸通航.本文针对一期工程施工临时航道通航水流条件问题,采用数值模拟计算方法,建立二维水动力数学模型对不同流量条件下的水流流态进行计算分析.结果表明:在施工一期时...     

Fish assemblage patterns across a gradient of flow regulation in an Australian dryland river system

Hydrological regime, physical habitat structure and water chemistry are interacting drivers of fish assemblage structure in floodplain rivers throughout the world. In rivers with altered flow regimes, understanding fish assemblage responses to flow and physico‐chemical conditions is important in setting priorities for environmental flow allocations and other river management strategies. To this end we examined fish assemblage patterns across a simple gradient of flow regulation in the upper Murray–Darling Basin, Australia. We found clear separation of three fish assemblage groups that were spatially differentiated in November 2002, at the end of the winter dry season. Fish assemblage patterns were concordant with differences in water chemistry, but not with the geomorphological attributes of channel and floodplain waterholes. After the summer‐flow period, when all in‐channel river sites received flow, some floodplain sites were lost to drying and one increased in volume, fish assemblages were less clearly differentiated. The fish assemblages of river sites did not increase in richness or abundance in response to channel flow and the associated potential for increased fish recruitment and movement associated with flow connectivity. Instead, the more regulated river's fish assemblages appeared to be under stress, most likely from historical flow regulation. These findings have clear implications for the management of hydrological regimes and the provision of environmental flows in regulated rivers of the upper Murray–Darling Basin. Copyright © 2010 John Wiley & Sons, Ltd.     

交汇河道水沙运动与河床响应研究进展

汇流是平原河网常见的河道形态,河网交汇处伴随着水流、含沙量、地形、水温、生态和环境等的突变,是控制水、沙、污染物输移的重要节点,因此了解汇流处水、沙等物质输移和特殊床面形态对日益恶化的河网水环境的综合治理有非常重要的理论和实际意义。笔者主要从交汇河道的特殊水流结构、泥沙运动规律以及河床对水沙运动的响应分别进行概述和总结,提出了目前交汇河道研究中存在的一些问题,并对交汇河道水沙运动与河床响应研究的研究方向提出了展望。     

明渠水流阻力系数计算公式分析与比较

按不同流态及流区对明渠水流阻力系数的计算公式进行了归纳和总结。以实测资料为依据,利用不同的阻力系数计算公式按明渠均匀流理论分别计算了实际输水明渠的过流能力,并将计算流量与实测流量进行对比,其相对误差在-7.9%～2.68%之间。其中,以紊流粗糙区的指数型公式和对数型公式的相对误差为小（-2.0%～2.68%）。在粗糙系数一定的条件下,不同阻力计算公式求得的阻力系数相差不大。从工程实用和计算方便的角度考虑,指数型公式较其它形式有更好的适应性,其计算的精确性往往取决于粗糙n的选择,用阻力平方区的公式计算过渡粗糙区的流量仍有较好的结果。     

三峡与丹江口水库下游河道河型变化研究进展

在收集三峡与丹江口水库下游河道河型研究成果基础上,总结与分析了三峡与丹江口水库下游河道不同河型的成因,包括来水来沙条件,河道边界条件和比降变化。结果表明,丹江口水库建成运用后,汉江中游河道演变为相对稳定的分汊或单一河道,下游弯道发生撇弯切滩;三峡水库建成运用后,下游河道的变化程度要小于汉江下游。指出了三峡水库下游河道河型变化的复杂性,及需要进一步研究的课题,研究成果可供大型水利枢纽工程下游河道河型变化机理研究参考。     

巢湖兆河分洪闸泄流特性试验研究

受周边地形条件及环境限制,巢湖兆河分洪闸与河道呈垂直布置,进流条件不利。针对分洪闸与河道垂直布置这一特征,分别对开敞式和涵洞式分洪闸进行了水工模型进口流态试验分析,结果表明涵洞式分洪闸进流流态优于开敞式分洪闸,能更好地保证各闸孔的均匀进流。针对涵洞式分洪闸方案,研究了分洪闸敞泄和控泄的泄流能力,指出敞泄状态下进口行近流速对流量计算影响明显,在水闸规划设计中,应计入行近流速影响。为改善消能效果及出口水流与下游的衔接,进行了多方案消能防冲改进试验,结果表明尾坎作为一种冲击式消能工布置在挖深式消力池末端,可使出口水流流速分布更加均匀并与下游水流衔接更为平顺,明显增强消能防冲效果。     

Fiber orientation distributions in slit channel flows with abrupt expansion for fiber suspensions

The lattice Boltzmann method was used to investigate numerically the fiber orientation distributions in slit channel flows with abrupt expansion for fiber suspensions even in the concentrated regime. The channels have a thin slit geometry with 1：4 and 1：3 expansions. Both the interactions between fibers and that between fibers and channel walls were taken into consideration. Some of numerical results are qualitatively in agreement with the experiment data. It is found that most of fibers are aligned in the flow direction in all the suspensions in the entrance region of the expansion. Fiber orientation distributions, having different patterns in different regions of the flow, depend on the expansion ratio of the channel. The mechanical fiber-fiber interaction largely affects the fiber orientation in the downstream of the expansion and in the salient corner for the cases of concentrated suspensions. The hydrodynamic interaction plays an important role on the fiber orientation in the dilute suspension.