低渗透污染土水动力弥散参数试验研究

污染土的治理中通常采用降低渗透性的措施来控制其二次污染。通过获得其水动力弥散参数可以对其二次污染进行评价和预测，但是现有的土柱试验以及求解方法不适用于低渗透污染土水动力弥散参数的测定和求解。针对低渗透污染土水动力弥散参数试验和求解的问题，提出采用改进的柔性壁渗透仪测定其污染物的穿透曲线，根据所获得的穿透曲线，采用数值反演的方法计算污染土的水动力弥散参数。结果表明，采用柔性壁渗透仪和数值反演的方法，能够满足低渗透污染土水动力弥散参数测定的需要。     

动水压力波高阶双渐近时域平面透射边界Ⅱ:计算性能

为了准确模拟动水压力波在半无限水库中传播引起的辐射阻尼，本文基于比例边界有限单元法构造了高阶双渐近时域平面透射边界。首先将描述半无限水库的连续波动方程转化为半离散的比例边界有限单元方程描述，然后通过特征模态变换将以动力刚度矩阵形式表达的控制方程解耦，获得了模态动力刚度的连分式解答，再通过引入辅助变量将透射边界在频域的动力刚度表达等效为一个高阶矩阵方程，对其施加傅立叶逆变换后即得到时域透射边界条件。频域模态动力刚度的计算结果表明：该双渐近透射边界可以在全频范围内迅速的逼近准确解，表现出优良的收敛性能。     

Hydrodynamic Characteristics of Chinese Sturgeon Spawning Ground in Yangtze River

Since the construction of the Gezhouba Dam on the Yangtze River in 1981, it has been found that the Chinese Sturgeon, Acipensor sinensis, performs natural propagation annually in a narrow reach downstream close to the Gezhouba Dam site. This might allow one to better investigate the river hydrodynamic conditions of the Chinese Sturgeon spawning ground. In this article, spatial Kinetic Energy Gradient （KEG） and absolute value of vorticity were computed along the river sections from measured data. The relation between Spawn Density per Unit Area （SDUA） and vorticity strength and between SDUA and KEG were worked out. The Results showed that the vorticity and KEG were both effective parameters for describing the hydrodynamic characteristics of Chinese Sturgeon spawning ground. The Chinese Sturgeons prefer to spawn in the river sections where the value of vorticity strength is larger than 0.4 s^-1 and KEG is larger than 0.029 Jkg^-1m^-1.     

Correlations for the particle deposition rate accounting for lift forces and hydrodynamic mobility reduction

A numerical procedure is presented which allows one to predict the deposition rate of microparticles suspended in a liquid flow onto the confining walls. Particle transport is not only diffusive but also affected by hydrodynamically induced lift force and reduced particle mobility. An appropriate expression for the lift‐induced migration is introduced into the numerical procedure. Its results agree quanititatively with previously published experimental data showing a significant effect of lift‐induced particle transport. Based on the numerical results algebraic correlations are obtained, which enable to calculate the particle deposition rate in situations where lift forces and mobility reduction diminishes the particle deposition rate.     

大湖之都大型楼盘区墨溪湖引水活水工程设计

工程选择了赣抚平原灌溉总渠为墨溪湖活水水源,并采用浅水湖泊平面二维水动力模型和水质模型模拟计算了引水活化需水水量,根据输水水流流态形式选择了合适的输水管材。为节约用地和避免影响周围景观,中途提升泵房设计为全地下式泵房形式。通过介绍工程设计情况,总结了工程设计特点。     

INVESTIGATION OF VORTEX SHEDDING INDUCED HYDRODYNAMIC VIBRATION IN VORTEX STREET FLOWMETER

0 INTRODUCTIONWhen a bluff body is placed in a flow stream,vortices form behind it and shed alternately from eachside. The shedding frequency keeps in a direct ratiowith the mean velocity over a wide range of Reynoldsnumbers.The idea of building a flow meter based on theassumption of a constant Strouhal number was firstproPOsed by Roshko, whose work indicated that theStrouhal number remains at an almost constant valueof 0.2 in the Reynolds number ranged 300 < Re <2 x l0s .For about thr…     

大型风电液力机械传动装置的理论分析

本文对大型风电液力机械传动装置的工作原理进行理论分析,介绍了其主要参数的计算方法.     

Behaviour of organised disturbances in fully developed turbulent channel flow

In our earlier work we have shown the relevance of stability theory in understanding the sustenance of turbulence in turbulent boundary layers. Here we adopt the same model to study the evolution of organised disturbances in turbulent channel flow. Since the dominant modes are wall modes we find that the stability characteristics in the two flows are nearly identical although the boundary conditions (at the edge of the boundary layer and at the centre of the channel) are different. Comparisons with the experiments of Hussain and Reynolds are also presented.     

铀溶液临界装置抗震分析

铀溶液临界装置充装大量液体,抗震分析采用简捷有效的附加质量法处理液动压力的关键问题.容器高架夹套、质量分布上重下轻以及连接松脱的结构特点导致系统抗震能力较差.对此,通过对交叉加固和平板约束方案的对比分析,最终采用在装置上部增加约束的方法极大提高了系统抗震能力,使装置抗震性能满足了有关要求,并为设计提供了可行的结构优化方案.