土坝基础中的结构不稳定土体

本文介绍了巴西一在坝基础中结构不稳定土体的性能数据。在巴西的几个大坝坝址处发现了这些土体，在这些土体所观测到的典型性能特征中，主要特征是在饱和状态下其抗剪强度会显著降低，本文简要描述了土要的三轴抗测试结果，测定了土样在几种饱和条件下的抗剪强度。在这几种测试中，土样的饱和程度随不同测试中所采用的饮和方法不同而变化，这些方法包括渗透法和渗透与反压相结合的方法，讨论了这些不同的饱和方法对除土体抗剪强度而     

现浇绿化混凝土的性能及其在生态护岸中的应用研究

为了减少水文环境对坡面混凝土的破坏,保护坡面植被,选取适宜坡面防护的现浇绿化混凝土开展性能测试,研究其在多水环境下的生态护岸工程中的应用价值。结果显示,现浇绿化混凝土平均抗压强度为7.2MPa,平均孔隙率为26.9%,测试结果满足工程设计指标要求;当降雨强度达到6.4L/min时,表孔参数对弗劳德数影响较大。研究表明,选择铺筑厚度高的现浇绿化混凝土护坡,有利于植物生长,能够缩短施工周期。     

大口径水表现场运行初探

本文介绍了武汉市自来水公司对大口径水表的现场测试的情况，虽然由于各方面条件的限制，测的结果还存在各种疑点，但若将所有数据作为一个整体，从测试的准确度和现场运行状态两方面分析，还是可以给我们一定的启示     

拱坝建基面岩体力学参数的复核

介绍广东省新丰县鲁古河拱坝在施工地质过程中通过取岩样进行室内试验、现场超声波测试岩石强度及完整性、用回弹仪测定坝基岩石抗压强度等3种方法，对岩石有关性质进行测试，并将结果进行比较、统计，修正了初步设计阶段中提出的岩体物理力学参数，提出比较符合实际的变形模量等物理力学参数值。     

粗粒土的三轴测试及其强度特性

大型高压三轴试验的试样尺寸大，施加的压力高，因此在土体抗剪强度的测定及测试手段等方面具有自身的一些特点。本文在大量粗粒料三轴试验的基础上，对不同土料的强度特性及其测试手段的特点进行了综合分析研究。     

碾压混凝土拱坝诱导缝开裂试验研究

通过多组由深埋椭圆裂缝、深埋矩形裂缝和穿透裂缝3种型式形成不同削弱度的碾压混凝土试件轴拉试验，研究了试件的应力强度因子，分析了不同裂缝的应力强度因子计算公式。由于试件的断裂韧度与裂缝形式无关，假设深埋矩形预留缝试件的应力强度因子可以由深埋椭圆预留缝或穿透预留缝试件的应力强度因子通过修正求得，建立了矩形预留缝试件应力强度因子的近似解析表达式。考虑了尺寸效应后，求得碾压混凝土材料的断裂韧度。根据碾压混凝土拱坝诱导缝的构造特点，并考虑了相邻缝的影响计算出诱导缝开裂的等效强度。这一结果应用于沙牌碾压混凝土拱坝开裂计算的三维非线性应力场仿真计算中。     

老混凝土建筑物强度现场测试成果分析

通过屈家店等闸混凝土强度现场测试结果，讨论应用回弹值推算强度的可行性。指出根据现场的芯样强度、回弹值及碳化深度测定值，求得相关关系后，其推算强度误差要较按全国或河北测强曲线计算小得多，并避免由测强曲线带来的系统误差。     

三峡坝区爆破噪声测试与分析

对三峡坝区不同爆破设计参数的爆破噪声及坝区边界敏感区的声学环境进行了测试，并对测试结果作了分析。     

矩形水柱瞬间溃塌水流演进特性

水库大坝溃决水流在一定程度上可以概化为矩形水柱瞬间溃塌水流,通过建立重力作用下矩形水柱瞬间溃塌的数学模型,模拟研究矩形水柱瞬间溃塌的水流特性,并基于量纲分析法得到了溃坝过程中坝址处的流量公式,对比分析了不同深宽比时坝址处流量的变化过程。研究表明:当深宽比相同时,坝址处的流量变化规律一致;当深宽比不同时,峰顶流量随着深宽比的增大而减小,且其出现时刻延后。同时,在此基础上推求得到了基于深宽比的坝址峰顶流量公式及峰顶流量出现时刻公式,得到了公式中峰顶流量系数及时间系数与矩形深宽比n的关系。研究结果可为溃坝水流问题的研究提供借鉴。     

多功能球阀水力性能测试分析

介绍了多功能球阀在野外、室内现场应用测试的目的、装置及方法，并分别对测试结果进行了分析。测试结果表明，多功能球阀结构简单、操作使用方便、制作容易、造价低廉、便于管理，可推广应用.     

AN INVESTIGATION OF FLOW CHARACTERISTIC OF AERATED DRAG REDUCTION IN TUBE

Under the aerated conditions of wall and top intube, the turbulent flow in the tube was measured by usingLDA. The turbulent structure of the flow field and the mech-anism of aerating drag reduction in the tube were discussed. It is shown that the energy dissipations of turbulence flow andmean flow will reduce and the flow velocity (or flow rate) willincrease by injecting mini-bubbles to the wall or top of tube,namely the effect of aerating drag reduction is attained.     

INFLUENCE OF YOUNG'S MODULUS ON DRAG-REDUCTION IN TURBULENT FLOW USING FLEXIBLE TUBES

In order to develop technologies of friction drag reduction with a flexible tube to be used for water transport, experimental studies were carried out on the influence of Young's modulus on the turbulent drag reduction. The friction coefficients of flexible tubes with different Young's modulus were examined by using a sleeve-tube structure. The fluctuating vibration of the outer wall and the fluctuating pressure on the inner wall of the tubes were measured with a laser displacement sensor and a pressure sensor. The results are as follows. The smaller the Young's modulus of a flexible tube and the larger the Reynolds number, the larger the turbulent drag reduction rates become. The transition from laminar flow to turbulent flow can be delayed with an appropriate Young's modulus. Non-dimensional amplitude of fluctuating vibration on the outer wall is smaller than that of a viscous sub-layer thickness, and is positively correlated with the friction drag reduction.     

不同进流浓度梭锥管水沙两相流场三维数值模拟

为了获得全面详细的梭锥管内部流动特性,本文探讨进流浓度对梭锥管内水沙分离效果的影响,据此来揭示梭锥管水力分离水沙的机理。本文采用重整化RNG(renormalization group)紊流模型与简化的多相流Mixture模型在泥沙浓度为5和15 kg/m3时对梭锥管内水沙两相流场进行了三维的数值模拟计算。并将计算结果与PIV测量结果进行对比,计算结果与PIV测试结果一致。结果表明:在进流量相同时随着进流浓度的增加,在上锥管边壁清水上升通道内速度增加,水流挟沙力增强,随水流溢出的泥沙量增多,并且随着进流浓度的增加梭锥管各个断面泥沙体积浓度及紊动强度值也随之增加,上锥管得到的清水面积也随之减小,不利于梭锥管内水沙分离。     

明渠交汇口三维水力特性试验研究

支流汇入主流后，在交汇口下游附近形成复杂的流动现象，对于确定渠道有效过流断面、泥沙及含有物质输移及淤积、渠底及边壁冲刷等产生重要影响。本文目的在于采用试验手段探索干支渠交汇口的三维流动结构。在一个矩形断面且等宽、45°交汇的半封闭自循环水槽中，应用五孔毕托球对明渠交汇口三维流动特性进行了试验研究。试验结果表明，对于给定交汇口形状及尺寸，分离区形状基本保持不变，尺寸随主支渠流量比变化并具有较好的相关关系；在和主渠轴线正交的横断面上交汇水流存在横向分速，水面附近横向分速指向交汇口对侧固壁，临底附近横向分速指向交汇口一侧。对于流量比较大的汇流流动，断面环流是交汇口水流三维流动的一个重要特征。     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF THERMAL-HYDRAULIC PERFORMANCE OF A CIRCULAR TUBE WITH EDGEFOLD-TWISTED-TAPE INSERTS

Three-dimensional numerical simulations and experiments were carried out to study the heat transfer characteristics and the pressure drop of air flow in a circular tube with Edgefold-Twisted Tape (ETT) inserts and with classic Spiral-Twisted-Tape (STT) inserts of the same twist ratio. The RNG turbulence model for mildly swirling flows, the enhanced wall treatment for low Reynolds numbers, and the SIMPLE pressure-velocity method were adopted to simulate the flow and heat transfer characteristics. Within the range of Reynolds number from 2 500 to 9 500 and the twist ratio y from 5.4 to 11.4, the Nusselt number of the tube with ETT inserts is found to be 3.9% ? 9.2% higher than that with STT inserts, and the friction factor of the tube with ETT inserts is 8.7% ? 74% higher than that of STT inserts. The heat enhancement is due to higher tangential velocity and asymmetrical velocity profile with the increase and decrease of the periodic velocity within an edgefold length. It is found that main factors affecting the heat transfer of ETT inserts are the twist angle and the gap width between the tube and inserts. A larger twist angle leads to a higher tangential velocity, and larger Nusselt number and friction factor. The thermal-hydraulic performance slowly decreases as the twist angle increases. The gap width between tube and inserts has a significant influence on the heat transfer, while little influence on pressure drops. The thermal-hydraulic performance increases in average by 124% and 140% when the gap width reduces from 1.5 mm to 1.0 mm and 0.5 mm. The larger the gap width, the higher velocity through the gap will be, which would reduce the main flow velocity and tangential velocity. So a small gap is desirable. Comparing experimental and numerical results at variable air flow and tube wall temperature, the numerical results are found to be in a reasonable agreement with the experiment results, with difference of the Nusselt number in a range of 1.6% ? 3.6%, and that of the friction factor in a range of 8.2% ? 13.6%.     

侧式进/出水口扩散出流紊动强度变化规律研究

为探求侧式进/出水口紊动强度变化规律,构建了RSM紊流模型用于侧式进/出水口流向、横向及垂向三方向上紊动强度研究,分析了进/出水口三方向上紊动强度分布沿程变化,重点关注了拦污栅处紊动强度变化规律。研究发现边、中孔三向紊动强度各断面轮廓基本一致,横向与垂向的紊动强度均小于流向紊动强度。在沿程分布规律上,壁面附近紊动强度在扩散段有减小的趋势,孔口中间紊动强度逐渐增大,水流经过扩散段以后有回转趋势。水头损失与紊动强度呈正相关,紊动产生的水头损失先增大后减小,壁面产生的水头损失与断面平均流速呈正相关。在此基础上,探讨了孔口高度、隧洞坡角、雷诺数对进/出水口三向紊动强度的影响。结果表明,雷诺数、孔口高度、隧洞坡角基本不影响紊动强度场的断面分布及沿程变化规律,但会影响拦污栅断面处三向最大紊动强度值及其所在位置。     

水泵水轮机泵工况压力脉动和转轮受力特性

为研究水泵水轮机在泵工况下的内部流态变化对压力脉动和转轮叶片受力的影响,采用 SAS－SST 湍流模型对某一模型水泵水轮机的多个非设计工况进行非定常数值模拟,分析了水轮机 内部流态对导叶与转轮之间无叶区、尾水管内的压力脉动和转轮叶片径向受力的影响。结果表明: 在流量为 40% ～80%设计流量时,导叶区内产生旋转失速,转失速涡团初生于固定导叶进口,并随着流量的降低向活动导叶进口发展,且覆盖区域逐渐增大。旋转失速使压力和过流沿周向不均匀分布, 导致压力脉动和转轮径向受力波动大幅上升。在40%设计流量时,失速涡团发展最为充分,无叶区 压力脉动和转轮受力波动的低频分量幅值最高。旋转失速产生的低频脉动可向尾水管传播,形成的低 频压力脉动幅值约为无叶区低频脉动幅值的10%。当流量低于 40%设计流量时,导叶区旋转失速消失,复杂的涡结构形成的压力脉动低频成分没有周期性。此外,转轮进口的流动分离使尾水管内产生复杂的回流涡结构,导致尾水管内形成频谱丰富的压力脉动; 流量降低使转轮进口回流涡结构的湍动 能增加,导致尾水管内压力脉动幅值大幅上升。小流量工况下,转轮进口的涡结构演变是转轮径向力波动的主要影响因素。     

组合隔板式鱼道水力特性数值模拟研究

鱼道是为鱼类提供洄游通道的一种重要的工程措施。基于Flow-3D采用标准RNG k-ε紊流模型和Tru-VOF追踪自由液面方法,对鱼道池室内流场进行三维紊流数值模拟,研究池室内水流流速、流态空间分布,分析鱼道的水力特性对目标鱼类洄游上溯的影响。结果表明:溢流堰与竖缝组合隔板式鱼道在设计流速v=0.75 m/s条件下,竖缝处平均流速为0.83 m/s,竖缝处流速分布范围为0.76~0.89 m/s;堰上流速为0.90~1.12 m/s,回流区流速分布范围为0.09~0.25 m/s,流速大小在鱼类的克流能力范围之内,但靠竖缝隔板处存在明显的主流贴壁现象。为此开展了池室优化方案设计,使鱼道池室流态满足鱼类上溯要求。     

用二维紊流模型反映三维紊流效应的一点尝试

本文在二维雷诺应力代数模型的基础上，引入了一个附加的雷诺正应力，并用此紊流模型计算了四孔水口连铸结晶器的二维流场，计算的结果表明，用这一紊流数学模型计算出的流场能够反映紊流的各向异性，将所得的计算结果与用二维激光测速仪所测结果对比，表明两者符合较好。     

Assessment of the predictive capability of RANS models in simulating meandering open channel flows

The predictive capability of Reynolds-averaged numerical simulation(RANS) models is investigated by simulating the flow in meandering open channel flumes and comparing the obtained results with the measured data. The flow structures of the two experiments are much different in order to get better insights. Two eddy viscosity turbulence models and different wall treatment methods are tested. Comparisons show that no essential difference exists among the predictions. The difference of turbulence models has a limited effect, and the near wall refinement improves the predictions slightly. Results show that, while the longitudinal velocities are generally well predicted, the predictive capability of the secondary flow is largely determined by the complexity of the flow structure. In Case 1 of a simple flow structure, the secondary flow velocity is reasonably predicted. In Case 2, consisting of sharp curved consecutive reverse bends, the flow structure becomes complex after the first bend, and the complex flow structure leads to the poor prediction of the secondary flow. The analysis shows that the high level of turbulence anisotropy is related with the boundary layer separation, but not with the flow structure complexity in the central area which definitely causes the poor prediction of RANS models. The turbulence model modifications and the wall treatment methods barely improve the predictive capability of RANS models in simulating complex flow structures.