Pipe-Wall Friction in Vertical Sand-Slurry Flows

This article describes the results of extensive laboratory tests of vertical flows of three sand fractions (0.12, 0.37, and 1.84 mm sands) in a 150 mm pipe. The tests revealed an interesting phenomenon of a surprisingly low contribution of the medium sand to the total friction of the mixture flow in the vertical pipe. The frictional pressure drop in highly concentrated flows at high velocities was lower for slurries of the medium sand than for slurries of both the fine sand and the coarse sand. The solids friction at the pipe wall is analyzed taking into account effects of particle-particle interactions and particle-liquid interactions in the boundary layer of a vertical flow of settling slurry. The analysis suggests that the observed phenomenon is associated with the hydrodynamic liquid lift force acting on solid particles traveling near a pipe wall. This off-wall force seems to be more effective for the medium sand particles than for the fine sand particles and coarse sand particles interacting with liquid in the boundary layer of the mixture flow. The excessive frictional pressure drop due to the presence of solids in vertical flows seems to be primarily produced by the combined effect of the Bagnold collisional force (the force that colliding particles exert against the pipe wall) and the liquid lift force acting on solid particles in the near-wall zone of the slurry flow.     

结构参数对蒸汽喷射压缩器性能的影响

采用有限体积法离散控制方程,标准k ε湍流模型,近壁面处使用壁面函数修正的方法对蒸汽喷射压缩器的超音速混合过程进行数值模拟。计算并分析了第二喉管与工作蒸汽喷嘴喉管面积比、喷嘴出口截面与混合段入口截面间的距离等几何参数对喷射器操作性能的影响。数值结果表明,喉管面积比及喷嘴位置的改变极大地影响着波系结构,在一定的设计工况下,总存在一个最佳的面积比及一个最佳的距离对应于最大的喷射系数,并给出了最佳几何参数下的主要物理特征。     

陶瓷复合体的抗热冲击性能研究

由陶瓷复合材料的抗热冲击实验，证明添加Ｗ（ＺｒＯ２）＝２０％时可使Ａｌ２Ｏ３复合陶瓷的热震温度达到３７０℃，如何添加Ｖ（ＳｉＣｗ）＝２０％可使Ａｌ２Ｏ３复合材料的热震温度达到４３０℃，使Ｓｉ３Ｎ４复合材料的热震温度达到６５０℃；如果采用Ｖ（ＳｉＣｗ）＝２０％，同时添加Ａｌ２Ｏ３，Ｙ２Ｏ３等活性剂，由于强化晶界的作用，可使Ｓｉ３Ｎ４复合材料的热震温度达到７００～７５０℃，还对各添加剂使陶瓷材料抗热冲     

核电站结构部件环境敏感断裂的系统监测和寿命预测

基于膜破裂滑移溶解机制导出的裂纹平均扩展速率关系式,结合电站运行工况的系统监测,运用反向直流电位降技术实现裂纹扩展的现场实时监测。该文已实际应征地国外一些核电站结构部件的完整性评估,寿命预测和优化电站运行工况等。本文介绍这一被称为ＳＭＡＲＴ（灵敏）监测的技术方法。     

库鄯输油管道减压阀性能及运行情况对比

为解决管道输送过程中大落差这一工艺难题,在库鄯输油管道的高点与低点间设立了减压站,通过减压站内的减压阀进行截流降压。文章介绍了库鄯输油管道RZD-RMBX型和CCI型减压阀的原理、结构、性能及技术参数,并对其运行情况进行比较,总结了各自的优缺点和调节性能上的差异,不仅对库鄯输油管道在不同工况下合理选用减压阀起到重要作用,而且对其他管道减压阀的选型也有一定的借鉴作用。     

沙尔湖浅埋煤层气注入/压降测试方法应用研究

针对沙尔湖构造浅埋煤层气储层低压低渗导流能力差、漏失严重及压力扩散情况复杂多变等特点,根据煤层构造特征和储层物性开展了浅埋煤层气注入,压降测试方法研究.优化设计了坐封位置、测试时间、测试最大注入压力和排量等参数,结合注入方式优化配置了井下测试管柱.通过优化设计和应用LPR-N阀、RD循环阀等新型测试工具,实现了大排量连...     

Radial explosion strain and its fracture effect from confined explosion with charge of cyclonite

Instrumented experiments were conducted in concrete models to study the explosion-induced radial strain and fracture effect of rock-like media under confined explosion with a charge of cyclonite. As a charge was exploded,two different radial strain waves were sequentially recorded by a strain gage at a distance of 80 mm from the center of charge. Through the attenuation formula of the maximum compressive strain(εrmax), the distribution of εrmax and its strain rate(ε) between the charge and gage were obtained. The effect of the two waves propagating outwards on the radial fracture of surrounding media was discussed. The results show that the two waves are pertinent to the loading of shock energy (Es) and bubble energy (Eb) against concrete surrounding charge, respectively. The former wave lasts for much shorter time than the latter. The peak values of εrmax and ε of the former are higher than those of the latter, respectively.     

基于能效分布矩阵方程的火电机组热力系统热经济性分析方法

定义了虚拟热力系统的概念,并在常规热平衡法、q—γ—τ矩阵形式和等效热降等概念的基础上,构造了热力系统能效分布矩阵方程。该矩阵方程全面反映了机组主系统和各种辅助系统对机组热经济性的影响状况,每个矩阵物理意义明确、规律性强,可以使热力系统的整体计算和局部分析变得更加清晰、简单、客观,非常适合于计算机程序化。     

钻铤因素对钻柱振动的影响分析

钻铤因素直接影响着钻柱振动的整体效果。钻铤长度是硬岩钻井中引起钻柱剧烈振动的一方面原因,同时也是解决钻柱振动的主要突破口。文中从钻铤的长度、固有频率、激励来源、钻铤共振及其临界转速、振动的控制等方面对钻柱振动问题进行全面分析论证,以公式的形式给出论证结果,便于钻井工程师们直接应用于生产实践。     

从全球气候变暖角度评替代冷媒HCFC—123与HFC—134a的使用前景

蒙特利尔议定书《修正案》规定了ＨＣＦＣ类化学品从２００４年起分阶段削减产量，联合国气候变化框架公约《京都协议》要求限期削减温室气体排放总量，以此为背景探讨了替代冷媒对全球环境问题的影响机理；在比较了两个国际环境协定的管制方法和前提的基础上，分析了ＨＣＦＣ－１２３的环境影响，提出了对ＨＦＣ－１３４ａ优势的三点反思；对两者的前景发表了四点看法。