三峡水电站水轮机蜗壳结构形式选择

目前国内外大型水轮机蜗壳结构主要有垫层蜗悫，充水加压蜗壳和安全联合承载蜗壳第三种形式。三峡水电站单机容量７００ＭＷ，蜗壳进口直径达１２．４ｍＨＤ值１７００ｍ＾２；机组台数多，且较长时间在低水头下运行，结合国外的经验，宜采用充水加压蜗壳，以确保机组安全运用。至于充水另压蜗壳可能存在的一些缺陷，经采取一些技术措施后也是可以解决的。     

Use of mesohabitat‐specific relationships between flow velocity and river discharge to assess invertebrate minimum flow requirements

The benthic macroinvertebrate community in the sixth order lowland River Spree (Germany) was investigated in order to assess ecological effects of a flow reduction. The benthic habitat was composed of visually distinguishable mesohabitats. Eight mesohabitats were delineated, Dreissena‐bank, unionid mussel bed, rip‐rap, coarse woody debris (CWD), alder roots, stable sand, shifting sand and mud. The mesohabitats differed in their physical structure and hydraulic nature. These functional habitats were partly inhabited by distinct invertebrate assemblages. The use of mesohabitat‐specific relationships between flow velocity and discharge seemed the most appropriate approach in order to assess the impact of flow reduction on lotic fauna. In combination with the species‐specific optima and tolerances for flow velocity, this approach can be used to develop a minimum flow level that mitigates the effects of flow reduction and enables the persistence of rheophilic invertebrates in their specific mesohabitat. Copyright © 2001 John Wiley & Sons, Ltd.     

Using an economic framework to inform management of environmental entitlements

There is much in the scientific literature dealing with methods to determine environmental water requirements in streams. However, most of these methods are suited to long‐term water resource planning and setting regulatory targets. In Australia, the environment is now recognized as a legitimate user of water with its own water entitlement. With this in mind, and in the context of a water market, transparent decisions need to be made as to how best to utilize environmental water reserves on yearly, monthly or even daily basis. Environmental water managers must identify priority flow components and environmental assets. This will call for information on environmental water requirements to be presented in a manner that informs operational decisions. This paper proposes that describing environmental requirements as a function relating to different flow levels, a relationship named here as an environmental response curve, is an important first step in making transparent decisions to achieve the best outcome from limited environmental entitlements. The environmental response curves allow the marginal benefit of water (or value of each additional ML) to the environment to be understood. This allows environmental recommendations to be more readily translated into operational rules. This is not a new environmental flows methodology. The contribution of this paper is representing existing data to allow operational decisions. This paper provides a possible way forward in representing environmental demands for operation of environmental water and highlights areas where our current knowledge falls short. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow and water temperature simulation for habitat restoration in the Shasta River,California

Low instream flows and high water temperatures are two factors limiting survival of native salmon in California's Shasta River. This study examines the potential to improve fish habitat conditions by better managing water quantity and quality using flow and water temperature simulation to evaluate potential restoration alternatives. This analysis provides a reasonable estimate of current and potential flows and temperatures for a representative dry year (2001) in the Shasta River, California. Results suggest restoring and protecting cool spring‐fed sources provides the most benefit for native salmon species from a broad range of restoration alternatives. Implementing a combination of restoration alternatives further improves instream habitat. Results also indicate that substituting higher quality water can sometimes benefit native species without increasing environmental water allocations. This study shows the importance of focusing on the limitations of specific river systems, rather than systematically increasing instream flow as a one size fits all restoration approach. Copyright © 2009 John Wiley & Sons, Ltd.     

纵向加速流绕椭球流动的精确解

本文基于理想不可压轴对称位流理论，导得纵向加速流绕椭球流动的精确解；利用Ｌｅｇｅｎｄｒｅ多项式还是导得椭球在静止介质中沿纵向作加速运动时，由此引起流体流动的精确解，以及这两种情况下作用在椭球上的附加阻力。所得结果具有一定的理论价值，且可用来检验数值计算方法。     

电厂从港池取水对进港航道及港池回淤的影响

在分析工程区域自然条件和泥沙条件的基础上，利用二维潮流数学模型的模拟电厂从港池取水对进港航道和港池水动力条件的影响，计算结果表明，电厂取水引起航道落潮流速降低产生的进港航道泥沙回淤及港池淤积不大。     

THE DYNAMIC EQUATION FOR A SPHERICAL BUBBLE IN UNIFORM SIZED SOLID PARTICLE-LIQUID HOMOGENEOUS SUSPENSION

The momentum equation for solid-liquid two-phase flow proposed by Elghobashi and Abou-Arab is taken as the governing equations for the liquid phase,and the Lagrangian dynamic equation for a spherical particle moving in the liquid flow as the basic equation for the relative motion of the particle in the liquid phase in the paper.The dynamics equation for a bubble in solid-liquid twophase flow is proposed,as well as the simplified equations under two extreme conditions with the relationship between the bubble collapse characteristic time τ_C~* and particle response time τ_(rel)~* being τ_C~*>> τ_(rel)~* and τ_C~* <<τ_(rel)~*.     

计算非均匀来流绕圆柱定常流动的流线：等涡量线迭代法

本文提出一种流线与等涡量线交替迭代的方法,用来计算速度剖面为折线的来流绕圆柱体的无分离流动。算例结果说明该方法可行。     

AN EXPERIMENTAL STUDY OF FLOW FIELD IN THE FLUID HOMOGENIZER

A Laser Doppler Anemometer (LDA) is used to measure and study the flow field in the working chamber of a homogenizer. Flow Patterns, distributions of mean and fluctuating velocities, shear rates are obtained in details. The characteristics of the flow field and the basic principles of homogenizing are presented. These results are very helpful for the improvement of fluid homogenizers.