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。     

阀笼式调节阀套筒窗口形状设计与流量特性分析

我国的阀笼式调节阀技术起步晚,传统的设计过程常常依赖经验公式,产品的实验结果与设计要求存在较大误差。因此,以阀笼式调节阀套筒为设计对象,基于阀笼式调节阀的孔板流量计原理,推导得到套筒横截面积的通用公式和4种流量特性(直线型流量特性、等百分比型流量特性、抛物线型流量特性和快开型流量特性)不同开度下套筒的横截面积,建立模型并用FLUENT软件进行仿真模拟,将调节阀在不同开度下相对流量的实验值与理想设计值进行对比。结果表明:此设计方法在调节阀开度为30%～80%时具有可靠性,不仅有效满足设计要求,而且该方法设计周期短、成本低、精度高。此外,通过推导的阀笼式调节阀套筒的通用面积公式,可改变套筒进口处和出口处的压力值和不同固有流量特性要求,得到符合特定要求的套筒,故具有一定的工程应用价值。     

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。     

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。     

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。     

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。     

滑板式调节阀流场的数值模拟及性能预测

针对新型滑板式调节阀产品模型,采用基于各向同性涡黏性理论的k-ε双方程模型求解,获得了阀门内部流场不同开度下的压力场和速度场,预测了阀门出现空化现象的位置,建立了阀门的流量特性曲线和流阻特性曲线。通过研究发现,滑板式调节阀流通能力强,具有线性流量调节功能;阀门在小开度情况下,内部流场紊乱,存在大尺度的漩涡;仿真结果可为此类新型阀门的开发与优化提供了依据。     

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%。     

电磁比例节流阀新型节流槽的建模与特性仿真

提出一种线性节流槽,利用它能够实现节流槽的过流截面面积与节流槽开口的大小呈线性正比例关系。将它用于电磁比例节流阀,可以实现通过节流阀口的流量与阀芯位移呈线性规律变化,配合使用比例电磁铁,很容易实现电磁比例节流阀的电信号对通过阀口流量的比例控制。根据电磁比例节流阀的实际工作环境,以MATLAB作为仿真平台,对电磁比例节流阀的稳态特性进行仿真,得到了电磁比例节流阀在不同开口时的流量特性曲线、刚度特性曲线和阀口开度与流量关系曲线,并对仿真结果进行分析,分析结果对于优化电磁比例节流阀的设计参数有重要的指导意义。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。