长洲水利枢纽库区移民安置规划设计

结合长洲水利枢纽水库淹没的特点,介绍长洲库区移民安置规划设计,提出了建设防护片工程、护岸工程、填土造田等措施来减少移民和淹没,同时结合当前移民安置的政策趋势,分析长洲水利枢纽库区移民安置规划存在的问题,并探求其他的移民安置方式.     

新建州河段暗渠输水系统水力过渡过程计算研究

运用特征线法研究引滦入津工程新建州河段暗渠水力过渡过程,建立了复杂边界条件的数学模型,采用不同的时间步长处理明流段暗渠缓流与临界流的过渡断面,计算因电站机组运行台数变化所产生的非恒定水流对明流段暗渠、调节池及满流段暗渠水力特性的影响,以及由此引起的暗渠输水流量变化特性,为工程设计及正常运行提供依据.     

基于特征辨识的PID水轮机调速器研究

介绍了一种基于特征辨识的PID水轮机调速器的设计方法,并引入了专家系统和智能控制的设计技术,通过水轮机调速器信息的在线提取,将其直接用于PID控制器和参数的在线整定。给出的仿真实例表明,该方法优于常规PID控制。     

双层堤基上覆层对堤基渗透破坏影响的试验

根据上覆层与下伏砂层的协调变形情况,将上覆层概化为完全不变形的刚性上覆层以及与下伏砂层始终协调变形的柔性上覆层,并利用室内试验对这2种极端情况进行模拟。通过对试验过程中的土体破坏情况、渗透流量、涌砂粒径以及破坏后土体的颗粒组成等方面进行分析,发现具有刚性上覆层的双层堤基在接触面上易形成空洞,而柔性上覆层较刚性上覆层具有更强的抗渗透破坏能力;同时,具有刚性上覆层的堤基发生渗透破坏时粗颗粒更易流失。对渗透破坏过程中的渗流场进行数值模拟,对比了不同渗透破坏阶段的水力梯度分析情况,简要分析造成2组试验差异的原因所在。研究结果表明,使上覆层与下伏砂层保持协调变形是控制渗透破坏发展的有效方法,建议在堤基建设时尽量增加上覆层柔性,使上覆层与下部土体有协调变形的能力。     

Hydraulic geometry of New Zealand rivers and its use as a preliminary method of habitat assessment

‘Downstream’ hydraulic geometry relationships describe the variation of water depth, velocity, and water surface width between rivers of different size at a characteristic discharge, whereas ‘at-a-station’ geometry describes the variation of hydraulic geometry with discharge within a reach. The instream flow incremental methodology (IFIM) also predicts the variation in water depth and velocity with discharge at a reach scale, so that hydraulic geometry relationships can potentially be used as a preliminary method of habitat assessment. Hydraulic geometry relationships were calculated from instream habitat surveys of 73 New Zealand river reaches with mean flows varying from 0.6 to 204 m³ s⁻¹ and an average gradient of 0.0047. The exponents of both at-a-station and downstream hydraulic geometry relationships were within the range of values reported in other international studies, although the exponents indicated that New Zealand rivers tended to experience greater changes in velocity and less in depth than the international average, probably because of high average gradient. The frequency distributions of water depth and velocity were positively skewed in most rivers, and on average the modal velocity was 90% of the mean velocity and the modal depth was 80% of mean depth. The use of at-a-station hydraulic geometry relationships for instream habitat assessment was compared to depth and velocity predictions using habitat simulation techniques (IFIM) in two streams. Measurements of stream width and depth at five cross-sections at two calibration discharges were used to establish at-a-station hydraulic geometry relationships. These predicted mean depth and velocity within 8% of the reach average values of the IFIM surveys within the range of calibration discharges and within 10–15% of the IFIM reach average when extrapolated beyond the calibration discharges. Hydraulic geometry can be used to indicate whether hydraulic conditions approach a ‘threshold’ such as a minimum acceptable depth or velocity, thus predicating the need for more extensive habitat survey and analysis. © 1998 John Wiley & Sons, Ltd.     

EFFECT OF AERATOR ON HYDRAULIC DRAG ACTING ON A CHUTE

The formulae used to calculate the friction in the non-uniform flow chute were examined with the experimental data. and the results show that the accuracy of the formula is enough for engineering applications. A comparison between the results of friction respectively from the uniform flow assumption and the non-uniform flow approximation indicates that the former is an order of magnitude larger than the latter in the case of steep chute. The hydr~3ulic drag on a steep chute with aerators was measured on the hydraulic model directly and the coefficient of the aerator effect on the drag was obtained. The variation patterns of the wall shear just down stream of the aerators were investigated and the mechanism of the increase in the drag by aerator were analyzed qualitatively with the measured water depths just downstream the aerators.     

液压动态仿真技术在抽水蓄能电站的应用探索

液压系统是抽水蓄能电站的一种重要动力设备,为了充分掌握其工作原理及工作过程,通过对深圳抽水蓄能电站尾水闸门液压系统进行动态仿真研究,从图形化建模实现系统仿真,模拟液压系统动态过程,实现故障分析和预控等应用需求;液压动态仿真系统也是学习和掌握液压设备的一套实用化辅助工具.     

长距离输水管道水力计算公式的选用

就长距离输水管道的材质、管道口径和衬里等管道特性因素,结合各设计规范的推荐公式进行了对比分析,并根据各水力计算公式的适用范围及限制条件,指出不同管道特性条件可能对水力计算结果造成的影响,建议在大口径长距离输水管道设计中采用对三个紊流区域均适用的柯列勃洛克公式替代海澄威廉公式,以期得到较为安全合理的设计成果。     

基于Weibull模型的混凝土冻融损伤寿命预测及应用

对北方严寒和寒冷地区水工混凝土结构而言,其抗冻性能是混凝土耐久性最具代表性的指标,也是影响工程实体服役寿命的关键因素。为了能够准确预测既有混凝土构筑物的使用寿命,本文以冻融损伤理论为基础,采用棱柱体试件进行了混凝土快速冻融物理模型试验,建立了基于Weibull模型和混凝土快速冻融试验的混凝土冻融损伤模型。基于该模型提出一种迭代逼近的混凝土寿命预测方法,通过室内试验和实际工程案例进行验证。结果表明：通过所建立损伤模型得到的冻融损伤预测值和试验实测值基本吻合,提出的寿命预测方法得到的预测数据较为可靠。     

凸台类型对离散型流道叠片过滤器水头损失的影响

离散型流道叠片过滤器是一种水头损失相对较小的新型叠片过滤器,其叠片表面均匀分布的凸台结构是影响叠片过滤器水头损失的主要因素之一。为探明凸台类型对内部流场的影响并进一步降低离散型流道叠片过滤器的水头损失,通过物理试验与数值仿真,对比分析了初始的右三角形和优化新增的菱形、椭圆形、上三角形、下三角形等共5种凸台类型的离散型流道叠片过滤器的水头损失及流场分布特征。结果表明：将离散型流道叠片过滤器凸台类型设置为下三角形有利于减小水流主流区与凸台边壁的接触长度和凸台间湍动能强度,降低离散型流道叠片过滤器的水头损失;与初始右三角形凸台相比,4种优化的凸台与主流区接触长度的降幅为9.61%~36.73%,最大湍动能的降幅为25.87%~49.96%,其中下三角形凸台降幅分别为29.99%和49.96%;根据模拟计算可得右三角形凸台流道间水头损失系数最大,下三角形凸台流道间水头损失系数最小,其能量转换效率最高;清水条件下,下三角形凸台离散型流道叠片过滤器水头损失相比初始离散型流道叠片过滤器降低了14.89%~21.93%。研究结果可为离散型流道叠片过滤器的结构优化提供参考。