新疆布仑口-公格尔水电站冲击式水轮机调速器机械液压系统设计

在新疆布仑口-公格尔调速系统设计中,采用国内外领先的液压控制技术,并结合国内外高水头冲击式机组的运用研究成果所制造的水轮机调速器机械液压系统完全符合工程应用.介绍了该六喷嘴冲击水轮机调速系统的机械液压系统的设计方案,包括喷针控制单元、折向器控制单元、事故停机集中控制单元以及结构设计,希望能对类似多喷嘴大型冲击式水轮机调...     

低压气体流量标定技术研究

热式质量流量传感器用于测量35～41 kPa(绝压)的气体流量,需在该工况下对其进行标定.采用文丘里喷嘴作为标准器,在被测流量传感器处构建调压系统,调节压力可至40±0.1 kPa(绝压),建立低压气体流量标准装置,通过比较流量传感器输出值与文丘里喷嘴标准流量,标定流量传感器.对常压下校准的喷嘴在35～41kPa(绝压)条件下是可以作为标准器进行了分析,试验证明:装置的稳定性为0.6%,重复性为0.13%,临界背压比为0.5,低压气体流量标定方法科学可行.     

Use of de laval nozzles in spray forming

Spray forming is a near- net- shape fabrication technology in which a spray of finely atomized liquid droplets is deposited onto a suitably shaped substrate or pattern to produce a coherent solid. The technology offers unique opportunities for simplifying materials processing, often while substantially improving product quality. Spray forming is applicable to a wide range of metals and nonmetals and offers property improvements resulting from rapid solidification (e.g., refined microstructures, extended solid solubilities, and reduced segregation). Economic benefits result from process simplification and the elimination of unit operations. Researchers at the Idaho National Engineering Laboratory (INEL) are developing spray forming technology for producing near- net- shape solids and coatings of a variety of metals, polymers, and composite materials using de Laval nozzles. This article briefly describes the atomization behavior of liquid metals in linear de Laval nozzles and illustrates the versatility of the process by summarizing results from two spray forming programs. In one program, low-carbon steel strip >0.75 mm thick was produced; in the other, polymer membranes ∼5 μm thick were spray formed.     

Study of Computational Issues in Simulation of Transient Flow in Continuous Casting

Unsteady three‐dimensional turbulent flow and heat transport in the liquid pool during continuous casting of steel slabs has been computed using several different computational models, domains, grids, and inlet conditions. The most advanced computations employ a large‐eddy simulation code, UIFLOW with a second‐order central‐differencing scheme, 1.6 million nodes and a realistic simulation domain including the complete submerged entry nozzle. The model has been validated in previous work through comparison with PIV measurements in caster water models, and with velocity and temperature measurements in an operating steel caster. The present computations are compared with flow measurements in a full‐scale water model and with heat flux measurements in a jet impingement test problem. Results are compared between model domains of the full caster with symmetric half‐caster and two‐fold symmetric quarter‐caster simulations. The effects of thermal buoyancy and the solidifying steel shell walls are studied independently. The effect of different inlet conditions is investigated by comparing results including nozzle simulations that are both coupled and uncoupled with the mold domain and a simplified nozzle geometry. The importance of the Sub‐grid scale (SGS) model for treating the small turbulent eddies is investigated through simulations with and without the Horiuti SGS K model. A rigorous grid refinement study is undertaken, which indicates criteria for choosing the element size near the walls. Accurate heat transfer predictions are more difficult to attain than accurate velocities. Finally, comparisons are made with Reynolds‐averaged approaches, including standard K‐ε and low Re‐number K‐ε model computations of the same system. The relative advantages and disadvantages of the different flow simulation methods are evaluated.     

湛江发电厂3号汽轮机汽流激振分析及处理

对湛江发电厂3号汽轮机汽流激振的机理进行简要分析,并根据3号机组汽流激振的特点提出了消除与预防对策。     

“田”字型双级双向热底冷盖熔铝炉

介绍一种与地方铝厂技术水平,生产规模,产品结构相适应原新型铝炉。该炉是将中,小型企业无法操作使用的巨型熔铝炉分解成两组双级,双向炉,采用冷炉盖,热底连体结构,与普通单炉相比可减少１６个散热面;采用炉料预热罩强制烟气循环预热炉可节省４０％以上。     

双射流流化床空隙率的分布

在 ３００ ｍｉｎ×５０ ｍｉｎ×２６００ ｍｍ的二维射流床中,采用内径为 １１ ｍｍ的对称双射流管,研究了等速射流条件下射流管间距、喷口射流气速、静床高度对床层空隙率分布的影响,发现射流管间距、喷口射流气速是双射流产生射流区合并的主要原因;并得到了具体实验条件下空隙率分布的数据．同时研究了双射流管不等速射流条件下空隙率分布的规律．     

流场对陶瓷喷砂嘴的冲蚀磨损影响

根据喷砂工作原理和喷枪结构特征建立了引射段的自由射流模型。以一种具体喷枪结构参数为计算对象，研究了嚷砂嘴从入口截面至出口处的流场性质和变化过程。并在此基础上分析了流场对磨料运动和冲蚀磨损的彩响。结果发现部分磨料对喷砂嘴入口端面材料造成接近垂直角度的撞击；入口段冲蚀角较大使磨损严重，沿着顺流方向冲蚀磨损率减小；在出口处形成的射流扩散角使冲蚀角有所增大，导致出口磨损严重。与实验结果进行比较，发现两结果吻合，证明了该理论分析的正确性。     

陶瓷喷砂嘴结构参数对冲蚀磨损的影响

根据喷砂工作原理和喷枪结构特征建立了引射段的自由射流模型。研究了喷砂嘴结构参数(粗糙度、内径、长度)变化时,喷砂嘴和喷枪内的气固两相流场性质和变化过程。并结合陶瓷材料的冲蚀磨损机理,分析了流场对磨料运动和冲蚀磨损的影响。结果表明,合理选择喷砂嘴的结构参数对减轻喷砂嘴的冲蚀磨损,提高其使用寿命具有重要作用。该结论对进行喷砂嘴的耐磨结构设计具有重要的指导意义。     

西门子SF_6断路器灭弧室结构及其时间特性测试

简要介绍了西门子SF6断路器灭弧室定开距、石墨喷嘴以及滑动触头的独特结构 ,分析了用普通电压降法进行时间测试存在的问题 ,指出应用动态时间测试法测试西门子SF6断路器时间特性的必要性。