套筒调节阀节流窗口型线参数化设计方法研究

针对套筒调节阀节流窗口型线设计难点,根据流体力学、流量特性和窗口型线几何方程的相关理论,对其等百分比流量特性的窗口型线进行参数化设计。以可调比为50∶1的DN80-Cv,max (44)套筒调节阀和DN200-Cv,max (275)套筒调节阀为例,基于理论研究设计其窗口型线。借助ANSYS Fluent软件,分别对两台阀门5%、10%、20%、…、100%开度模型进行仿真,得到各开度下仿真流量系数与理论流量系数之间的误差均不超过10%,满足节流窗口精度设计要求。分别对两台调节阀5%、10%、20%、…、100%开度模型进行流量试验。结果表明：阀门在5%和10%开度时,试验流量系数和理论流量系数误差较大;在20%~100%开度时,试验流量系数和理论流量系数误差均在10%以内,且流量控制精度较高;节流套筒与阀塞之间的环向间隙对阀门小开度时的流量系数影响较大;理论流量特性曲线、仿真流量特性曲线和试验流量特性曲线高度吻合,验证了所提方法的正确性。     

单座柱塞式调节阀等百分比型流量特性设计研究

通过研究调节阀的流阻系数，发现调节阀的流阻系数主要受阀体和阀芯两部分结构影响。将调节阀的结构特性与等百分比型流量调节特性相结合，推导出等百分比型调节阀各开度下流通面积的求解公式，并依据该公式计算结果运用等值面积曲线法给出了柱塞式调节阀阀芯型线设计方法。结果显示：依靠该方法所设计的阀芯，调节阀仿真模拟得到的流量调节特性与理想流量调节特性高度吻合。该方法有较高的准确性和可靠性，在一定程度上减轻了传统阀芯设计需要多次进行试验修正的工作量。     

套筒调节阀等百分比节流套筒开孔参数化研究

针对套筒调节阀节流套筒设计难点,根据调节阀流量方程和流量特性的相关理论,结合开孔几何设计方程,对其等百分比流量特性的节流套筒开孔进行参数化研究。以可调比为50∶1的DN50(C_(vmax)24)、DN250(C_(vmax)450)和DN500(C_(vmax)1860)套筒调节阀为例,进行多孔节流套筒的设计。采用Fluent仿真软件,分别对3台调节阀10%、20%、30%、40%、50%、60%、70%、80%、90%和100%开度时的模型进行仿真试验。结果表明:DN50(C_(vmax)24)套筒调节阀除10%开度外,其余开度时仿真和理论流量系数相对误差均在10%以内;DN250(C_(vmax)450)和DN500(C_(vmax)1860)套筒调节阀所有开度时的仿真和理论流量系数的相对误差均在10%以内,且相对精度较高;理论和试验流量特性曲线高度吻合。研究结果弥补了该套筒调节阀节流套筒设计方法上的不足,为调节阀行业的发展提供助力。     

多孔型套筒阀流量数值仿真与试验研究

按照调节阀流通能力的定义设定边界条件,利用FLUENT流体仿真软件对多孔型套筒阀进行数值模拟分析,仿真得到其流量特性。搭建了循环式多级并联调节阀流量试验平台,并对套筒阀进行检测,得到其流量特性曲线。通过对比试验数据、仿真数据以及标准直线流量特性曲线,可知测试阀仿真流量特性与试验值相吻合,误差在允许范围内,说明仿真数据和试验检测结果可靠。仿真数据和试验方法可为设计开发具有高精度流量特性的调节阀提供参考。     

面向调节阀的流量控制仿真研究

针对柱塞式调节阀进行流量反馈控制时过于依赖流量测量装置、流量调节时间长的问题，进行流量控制仿真研究。基于Fluent流体仿真软件，建立10%～100%开度值下的调节阀三维流道模型，并在0.2～1 MPa进出口压差下仿真得出调节阀内部流场分布，建立阀口流量与阀芯开度、调节阀进出口压差三维数据表。建立调节阀开度控制模型，同时完成模糊PID控制器的设计。通过MATLAB对3种调节阀流量控制系统进行仿真分析。结果表明：基于所设计的开度控制模型进行流量调节时，有效地提升了阀门的快速性，阀门开度响应时间小于1.8 s,同时完全消除了超调量，更易达到稳定状态。     

基于CFX的迷宫式调节阀内流场流动特性的仿真

针对某特定型号的迷宫式调节阀,用SolidWorks建立其三维实体模型,通过布尔操作取其内部流场作为研究对象。应用CFX方法对调节阀内部流体流动特性进行仿真,得到该阀内流场流动的三维可视化结果。根据仿真结果分析迷宫式调节阀内部流场的流动特性,得到在阀芯不同开度下该阀的理想流量特性曲线以及相同开度下压差和质量流量之间的关系曲线,为后续研究新的阀门、阀门故障诊断以及阀门流场优化等研究提供很重要的参考。     

直线型柱塞式平衡调节阀结构优化研究

为解决依靠经验公式设计的柱塞式平衡调节阀流量特性与预期的直线型偏差较大的问题，提出一套优化直线型柱塞式调节阀阀芯结构的方案。该方案将流量系数与流量系数增量共同作为评价线性贴合度的准则，以实验测试为前提，以数值模拟为主要手段，逐段对阀芯结构进行调整优化，并通过数值模拟来验证方案的合理性以及准确性。结果表明：依靠该方案优化后的阀芯结构使得流量特性高度贴合直线型，各开度下流量系数较理论值的偏差由优化前多数在8%以上降低到集中在2%以下；各开度下流量系数增量较理论值的偏差由优化前多数在15%以上、最大值达63.26%降低为集中在5%以下、最大值仅为13.62%。     

基于CFD的调节阀内流场流动特性研究

针对某调节阀,建立其三维流场模型。应用CFD方法对调节阀内部流体流动特性进行仿真,得到该型号调节阀内流场流动特性的三维可视化结果。根据仿真结果分析调节阀内部流场的流动特性,得到在阀芯不同开度下调节阀的理想流量特性曲线以及相同开度下流量和压降的关系曲线,为后续的阀门故障诊断及流动性能优化等研究提供参考。     

迷宫式调节阀内部流动与损失量化研究

迷宫式调节阀具有独特的迷宫式盘片结构,在减缓或避免旁路系统中出现汽蚀、闪蒸、振动和噪声等不利影响时起重要作用。然而,盘片结构也会导致阀内流场变化复杂,流动损失加剧。介绍迷宫式调节阀的工作原理,建立调节阀仿真模型,通过流量系数和质量流量验证仿真模型的准确性。对不同阀口开度下的气动特性进行分析,并利用熵产率及熵产率体积分数对各开度下损失进行量化研究。结果表明：随着开度的减小,阀内速度整体呈减小的趋势,但压力并未呈线性变化;阀内低频段的速度波动,可能是导致阀内噪声和流致振动的重要原因;高损失区域主要集中在迷宫盘片的通流区域,而损失随着开度的增大呈规律性增大。     

纯水节流阀口抗气蚀性能实验研究

介绍了纯水节流阀口和气蚀试验模型的设计，实验对比研究了异型纯水节流阀口和常用的锥形节流阀口的抗气蚀性能。在不同的流量、压力和阀口开度等实验条件下，研究了两种不同结构节流阀口的流量-压差特性；对在不同阀口开度和进口压力下阀出口压力脉动进行了频域分析，得出了其相应的临界气穴系数。实验结果表明：采用异型原则设计的纯水节流阀口较常用的锥形节流阀口流量-压差特性曲线的斜率小，即刚度大，临界气穴系数小，抗气蚀能力强，阀口两端能够承受更大的压差。     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.