三峡电站排沙孔工作门区及通气管道空化特性研究

针对三峡电站排沙孔工作门区及通气管道设计体型,通过减压模型试验研究了通气孔分流对高流速有压泄水段空化特性的影响。成果表明:在通气孔节制阀全开时,通气孔底部出口区会产生强烈的蒸汽型空化,而节制阀区无蒸汽型空化发生;在通气孔节制阀半开或全关时,上述两部位的空化强度大大降低,基本上无空蚀破坏的危险性。为保证高流速有压泄水建筑物安全可靠的运行,工程上要避免该部位出现分流设计。     

不对称引水系统双调压井涌波研究

在无阻尼的假定下,建立并求解了不对称引水系统双调压井涌波的二元二阶微分方程组.研究表明:双调压井涌波存在两个波动频率,任意一个调压井涌波波动为两个波函数之和,而涌波波幅与引水系统水力参数、涌波方程的初始条件有关.以某电站为例,采用两机组导叶瞬间关闭的假定处理初始条件,研究调压井涌波波幅与引水系统水力参数的关系,揭示了不对称双调压井引水系统控制工况下,小机组对应的小调压井涌波波幅在一定范围内并不随着调压井面积的增加而减少的特殊现象.提出不对称引水系统双调压井的面积设计还应根据涌波波幅与调压井面积的变化曲线、避开使得调压井涌波波幅较大的区域的观点.     

一维河流水团示踪试验数据的模糊线性回归

将模糊线性回归的概念引入分析河流水团示踪试验数据、确定河流水质参数的计算过程中,建立计算河流水质参数的模糊线性回归模型,利用该模型能计算出不同置信水平下水质参数的取值范围。算例验证结果表明,应用模糊线性回归模型可以有效地确定河流的水质参数,且计算过程具有一定的稳定性、可靠性和灵活性,模糊线性回归模型是分析河流水团示踪试验数据、确定河流水质参数的一种有效的途径。     

水轮机水力阻抗特性研究

推导了开度不变、转速不变和出力不变、转速不变两种运行条件下水轮机水力阻抗计算公式,分析了这两种运行条件下机组水力阻抗的差异,指出在混流式水轮机运行范围内,在前者条件下机组水力阻抗大于0,在后者条件下机组水力阻抗小于0.通过理论分析和数值计算相结合的方法,研究了机组水力阻抗对水电站有压输水系统自激振动特性的影响.研究表明:机组水力阻抗的正负决定了系统衰减因子的正负及大小,对系统频率的奇偶性具有选择性.     

Flow resistance in a compound gravel-bed bend

In this paper, the effect of a gravel-bed in a compound bend (similar to sinusoidal top view) of a natural river (Zayandehrud River flowing through Isfahan, Iran) has been investigated for flow resistance analysis, measuring the velocity with a micro current meter. The data were analysed and the following observations were made. In a compound bend, the law of the wall can be valid for up to 66% of the flow depth from the bed. The parabolic law is the most effective method for the determination of shear velocity. Based on the existing criteria for verifying the equilibrium boundary layer, the flow cannot be in equilibrium. The shear stress distribution and the sediment transport parameters have considerable influence on resistance to flow. Froude number and the flow depth relative to the representative gravel size have little effect on the flow resistance estimation.     

三峡水利枢纽工程非恒定流通航影响研究Ⅰ:上、下引航道

三峡水利枢纽在汛期调洪和船闸充、泄水运行全过程,在上、下游引航道内将产生不同程度的非恒定流,对航运构成相应的不利影响。本文结合坝区河势特点及上下游引航道布置,试验研究了大坝泄洪及船闸充泄水非恒定流对上、下引航道通航影响,同时进行了非恒定流通航条件评价及改善措施研究。     

二维有自由面渗流分析的有限元并行计算

建立了一个基于MPI消息传递的微机机群系统,进行了有自由面渗流的有限元并行分析。通过预处理共轭梯度法和逐个单元法技术的结合来求解方程组,采用前后处理的并行、负载均衡等技术,改善了程序性能。通过对土坝渗流进行并行数值模拟验证了模型的正确性和有效性。加速比、计算效率和可扩放性的测定表明,该模型对大型问题能够减少存储空间,提高运算速度,具有良好的可扩放性,有能力对大型工程,特别是土坝的渗流问题进行快速精确的模拟。     

淹没扩散出流不稳定现象研究

抽水蓄能电站上水库的进出水口,在抽水工况下,各个水平分流孔口的出流类似于矩形扩散管嘴的淹没出流。针对国内某一在建的抽水蓄能电站上库进出水口的模型试验;采用先进的量测手段,获得了大量进出水口拦污栅处的三维流速资料,发现出水口的水流流态是不稳定的,除随机的脉动外还存在不稳定的摆动:对各流速分量进行了频谱分析和相关性分析,得出各分量的摆动频率和脉动频率及其互相关系数。研究成果可作为进出水口拦污栅设计的参考。     

Case Study: River Training and Its Effects on Fluvial Processes in the Lower Yellow River, China

More than 50?years’ river training practices in the Lower Yellow River provide valuable experience in river management for flood control in rivers having rapid flow changes, silting beds, and active channel migrations and are of importance in understanding the fluvial processes in regulated rivers with high sediment loads. Planned channel alignments for river training in the Lower Yellow River usually consist of a series of consecutive moderate bends representing the natural tendency of flows. Flow guide works, namely spur dikes, were constructed on the concave banks of the planned bends to protect the channel against scouring and migration by deflecting the current away from bends and further guiding the main flow from one bend to the next one. As a result, well-planned flow guide works can play a crucial role in limiting channel shifting and migration and in establishing a relatively stable channel. Enough flow guide works, on both sides together reaching about 80% of the channel length, may change the transitional and braided channel patterns to a confined meandering pattern.     

快速干道路基排水测试方案研究

在上海市外环线(浦东段)二期工程中，突破了传统的道路排水设计，设置了综合排水试验段，建立了自动化的综合排水测试系统，实现了数据自动采集并通过电话拨号上网进行远程传送。着重论述了路基排水测试系统的水力学设计。