EFFECTS OF SPLITTER BLADES ON THE LAW OF INNER FLOW WITHIN CENTRIFUGAL PUMP IMPELLER

Analysis on the inner flow field of a centrifugal pump impeller with splitter blades is carried out by numerical simulation. Based on this analysis, the principle of increasing pump head and efficiency are discussed. New results are obtained from the analysis of turbulence kinetic energy and relative velocity distribution: Firstly, unreasonable length or deviation design of the splitter blades may cause great turbulent fluctuation in impeller channel, which has a great effect on the stability of impeller outlet flow; Secondly, it is found that the occurrence of flow separation can be decreased or delayed with splitter blades from the analysis of blade loading; Thirdly, the effect of splitter blades on reforming the structure of "jet-wake" is explained from the relative velocity distribution at different flow cross-sections, which shows the flow process in the impeller. The inner flow analysis verifies the results of performance tests results and the PIV test.     

活性炭对氙的动态吸附性能及其结构表征分析

近年来,活性炭吸附放射性氙被越来越广泛应用于核电项目的尾气处理中。活性炭对氙的动态吸附系数与其孔结构关系甚大,而相关研究却很少,因此有必要研究二者的关系,为活性炭的选择与开发提供参考。本研究通过动态吸附平台测定温度为25C、表压为0时的四利活性炭对氙的动态吸附系数,并利用氮气吸附以及扫描电镜对活性炭进行分析表征。结果表明,比表面积为991.9 m~2/g的JH12-16活性炭对氙的动态吸附数最大,且活性炭对氙的动态吸附系数不和比表面积或孔容成正比关系。中孔和大孔对吸附氙只是起着通道作用,最佳吸附氙的孔径在0.55-0.60 nm。     

脉冲激光辐照ZrO2涂层的18-8不锈钢快凝组织与精细结构

利用脉冲激光辐照研究超高温度梯度下表层预置ＺｒＯ２纳米颗粒涂层的 １８－８奥氏体不锈钢的快凝组织形态、微结构特征及力学性质，结果表明，在表层约１５μｍ范围内形成Ｚｒ的合金化微区， Ｚｒ最大含量（原子分数）为４３．３％，但Ｚｒ成分分布存在不连续特征；预置纳米 ＺｒＯ２陶瓷涂层明显提高了激光作用深度．超高温度梯度和高冷却速率显著细化了快凝亚组织并得到超细枝晶及胞晶，并观察到位错胞及栅栏李晶两类亚晶，而激光熔区的外延生长机制未使晶粒细化．激光辐照后，合金化区硬度增加而弹性模量降低，其余部分硬度增加而弹性模量无变化．     

加氢反应进料泵机械密封泄漏分析及处理

对加氢反应进料泵(GA-102A/B)的机械密封泄漏的主要原因进行了计算分析,指出摩擦副端面温度过高是导致机械密封失效的主要原因,通过采取对机械密封安装前的检查、对机械密封辅助冷却系统的改造等措施,解决了密封泄漏问题。     

Poly (vinyl alcohol)-assisted solvothermal growth of CdS dumbbells and necklaces

Novel dumbbell-like and necklace-like CdS was synthesized via a facile solvothermal route using poly (vinyl alcohol) as assistant agent. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, and photoluminescence spectrophotometer. Based on time-resolved experiments and comparative experiments, a possible nonequilibrium–equilibrium growth mechanism was initially proposed.     

Singularity Characteristics for a Lip-Shaped Crack Subjected to Remote Biaxial Loading

In this paper, the conformal mapping method was adopted to solve the problem of an infinite plate containing a central lip-shaped crack subjected to remote biaxial loading. A kind of leaf-shaped configuration was also constructed in order to solve the problem. The analytical result showed that the singularity order of the stress field at the tip of a lip-shaped crack remains -1/2, despite the difference in notch-crack width. This revised version was published online in July 2006 with corrections to the Cover Date.     

放映镜头的结构与使用注意事项

一、单片透镜的各种像差单片透镜存在许多缺点 ,它所成的像不能完全反映原物体的真实面貌。这种影像与原物体不一致的现象称为像差。透镜的像差可分为两种 ,由于透镜对各色光的折射率不同而引起的像差称色像差 ;由于透镜各部分对光的折射作用不同而引起的同一色光的像差 ,称单色像差。单色像差又分为球面像差、彗形像差、像散及像场弯曲和畸变等。1.球面像差(1)凸透镜的球面像差 :对凸透镜照射一束宽阔而与光轴平行的光线 ,经过透镜后不在光轴一点上汇集 ,这样一种被透镜折射后的光线焦点不一致的现象称为球面像差 ,如图 1所示。近轴光线在…