冷却孔复合角和排列方式综合作用对平板气膜冷却效果的影响

研究复合角和排列方式综合作用对平板气膜冷却效果的影响。采用数值模拟的方法,保持射流圆孔尺寸、间距及倾斜角不变,分别对四种孔阵的平板气膜冷却进行了流动和传热的分析。利用Realizable k-ε湍流模型,标准壁面函数边界处理和SIMPLE算法,分析速度、涡量、冷却效率,对比冷却孔复合角和排列方式综合作用对平板气膜冷却效果的影响。结果显示:复合角和叉排同时存在时可改善平板展向上的冷却效果,而在平板流向上对冷却效果的影响不明显。结合吹风比得出较优的孔排方式。     

Payments for watershed services: Directing incentives for improving lake basin governance

This study introduces the emerging integrated ecosystem management approach known as Payments for Watershed Services (PWS) as utilized for lake and reservoir basin governance. PWS is built on the central concept of providing economic incentives to watershed stakeholders to assist in management efforts. It channels conservation payments from downstream payers to finance conservation activities conducted by upstream payees. The upstream conservation activities are expected to enhance ecosystem functions, thereby improving water‐related ecosystem services desired by downstream stakeholders. Information on 163 PWS projects in 34 developing countries through the year 2008 was collected and analysed, including their common goals, processes, outcomes, scientific assumptions and socioeconomic rationales. This study recognized one unique PWS characteristic, namely the role of intermediary organizations (i.e. brokers) in integrating the economic incentives of upstream payees and downstream payers in order to facilitate their transactions by means of contracts. Although 75% of the reviewed PWS projects have focused on rivers, and only 10% have considered lakes and reservoirs, the similarity of the intermediary functions performed by lake management organizations and PWS intermediary organizations suggests a greater potential for the future application of PWS designs in lake basins. Drawing on components in the field of New Institutional Economics to interpret the intermediary function within the PWS framework, a three‐part PWS design with 15 steps is proposed in this study for lake basin governance, with a Costa Rican PWS scheme serving as an illustration. This study seeks to communicate the scientific and socioeconomic frontiers for developing locally suitable and integrated watershed governance structures to lake management organizations and other watershed stakeholder groups.     

保证混凝土框架柱延性的设计方法

框架柱是混凝土框架结构的关键构件,其延性很大程度决定了整个结构的延性水平。为探讨如何在设计中保证混凝土框架柱的延性,结合我国混凝土结构抗震设计规范,较为系统地总结了从概念设计、材料选择、确定柱的延性需求及延性水平到构造措施的完整设计方法。研究发现,缜密的概念设计、合理的柱截面尺寸及配箍对保证柱的延性至关重要。     

桩群排列方式对水流结构特性的影响

利用室内水槽试验模拟了桩群不同排列方式工况下水流的运动规律,借助三维超声波多普勒测速仪(ADV)量测了不同断面、不同垂线、不同测点的时均流速,得到了不同工况下的流速分布、紊动强度、雷诺应力,并分析了它们的变化特征。结果表明:桩群使流速重新分布,在桩群区与非桩群区交界处流速明显减小,且桩群布置密度大时,水流绕流流速最大;当桩群排列方式改变时,各断面的三向紊动强度都会发生较大改变,但是对于某一方向上的紊动强度各断面仍有一定的相似性;修桩后雷诺应力分布规律有所不同,水流上侧的雷诺应力较大;桩群排列方式的改变不仅使雷诺应力沿程变化较大,而且改变了雷诺应力时均值的大小及最大值出现的位置。     

新形势下水利质量管理制度体系构建与制度安排

从制度层面分析了新时期的水利质量管理问题.宏观上,在对现有水利质量管理制度诊断和梳理基础上,考虑构建中国水利质量管理制度体系框架;微观上,重点树立民生水利理念,并基于服务管理视角创新性地提出制度安排模型.     

瀑布沟水电站导流洞封堵施工

瀑布沟水电站两条导流洞均布置于左岸,洞轴线相距45 m,在封堵施工中,于永久堵头施工前先完成临时堵头施工,在临时堵头的保护下再施工永久堵头。临时堵头浇筑不分层,通仓浇筑,确保其施工快速完成,发挥挡水功能。永久堵头分两段、分层施工,在仓内布置钢筋并布设了固结灌浆、回填灌浆和接缝系统,并在永久堵头与临时堵头接合处设置钢筋网。     

桥巩水电站工程金属结构设计

文章介绍桥巩水电站工程金属结构的设计成果、启闭机的选型、闸门的结构设计特点及门槽设计的新思路和方法。目前电站已运行多年,闸门和启闭设备运行良好,证明设备选型正确、布置合理、设计是合理、可靠的。     

Process intensification of fine coal separation using two-stage flotation column

Flotation column is widely used as the separation equipment for fine mineral due to its high selectivity. However, this device may be unsuitable for the coarse particle flotation and has high handling ability. A two-stage flotation column with dimensions of 2 000 mm× 1 000 mm×4 000 mm was designed to enhance the column flotation process. The energy input was modified by adjusting the flow rate and the head of circulating pump. The flotation column was designed with low energy input in the first stage （speed flotation stage） to recover easy-to-float materials quickly, and high energy input in the second stage （recovery stage） to recover difficult-to-float minerals compulsorily. Contrast experiments on the throughput and coarse coal recovery of high ash coal from the Kailuan Mine were conducted using conventional single-stage flotation column and the two-stage flotation column. The results show that the combustible matter recovery of the two-stage flotation column is 5.25% higher than that of the conventional single-stage flotation column. However, the ash contents of clean coal for both columns are similar. Less coarse coals with low ash are obtained using the two-stage flotation column than that using the single-stage column flotation with the same handling ability. The two-stage flotation column process can enhance coal flotation compared with the conventional single-stage column flotation.     

塑料花环填料液相总传质模型的估测

采用塑料花环填料,研究了空气-氧气在水中的解吸过程,解吸在常温常压下进行,采用溶氧仪测试氧在水中的浓度,根据实验数据得到了液相总体积吸收系数关联式.该式不仅简单,使用方便,且实验值与计算值较一致,实验结果对塑料花环填料的设计有一定的指导作用.