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针对风机叶轮过载失效的情况,计算风机叶轮的载荷.利用三维软件建立叶轮三维模型,详细介绍三维湍流风模型的建立过程,仿真得到3种不同风速的湍流风模型下叶轮所受载荷,并对其进行分析,为风力发电机组主要零部件的优化设计提供参考. 相似文献
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建立了基于同位网格的结晶器内流场与温度场耦合计算的数学模型,并采用大涡模拟的湍流模型对结晶器内的瞬态流动进行研究。该模型适用于形状不规则的六面体网格。使用滞后修正的QUICK格式改进了对流项的离散格式,提高了程序在高雷诺数和不规则网格计算条件下的稳定性。使用块结构化网格对计算区域进行了剖分,对结晶器内瞬态流场进行了模拟,结果表明流场具有不对称性和不稳定性,水口射流存在周期性的摆动,上回流区位置和自由表面波高周期性变化,并且这些非稳态现象之间存在相互关联。 相似文献
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作者研究了冷态模型中模拟风口回旋区气流的流动结构,由此确定了一个重要的影响高炉气流分布的边界条件。发现在风口回旋区有一个由环流包围的限制流动型的中心射流流股。在电子计算机上对流函数的Laplace方程和矢量化的Ergun方程导出的流函数方程进行有限差分解法,得到了一些流线图,从而研究了高炉下部的气流分布及影响因素。计算表明高炉下部气流分布与回旋区的流动结构有密切的关系,这些结论对研究和控制高炉过程有一定参考价值。 相似文献
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作者研究了冷态模型中模拟风口回旋区气流的流动结构,由此确定了一个重要的影响高炉气流分布的边界条件。发现在风口回旋区有一个由环流包围的限制流动型的中心射流流股。在电子计算机上对流函数的Laplace方程和矢量化的Ergun方程导出的流函数方程进行有限差分解法,得到了一些流线图,从而研究了高炉下部的气流分布及影响因素。计算表明高炉下部气流分布与回旋区的流动结构有密切的关系,这些结论对研究和控制高炉过程有一定参考价值。 相似文献
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《特种铸造及有色合金》2017,(3)
以流体力学有关理论为基础,应用FLUENT软件建立高炉鼓风系统的模型。根据高炉操作工艺的需要,通过改变高炉某几个风口的直径,堵塞某几个风口,模拟研究这种操作对各风口间风量分配的影响;模拟研究风口回旋区的形状,并确定风量、风压、焦炭粒度和风口直径等对风口回旋区形状的影响。结果表明,堵塞风口将导致各风口间风量分配的不均匀性加大;风口直径减小时,该风口处的风量将显著减少;风口回旋区深度随风量、风温、风口直径以及风口插入深度增加而增加,随风口前焦炭粒度的增加而减少。 相似文献
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为了能够反映固液相变过程中潜热等对熔池动态行为的影响,基于旋转高斯体热源与高斯面热源相结合的混合热源模型,分析了相变潜热对焊接熔池温度场和熔池形状的影响.计算结果表明,在铍材激光钎焊过程的温度场和流场分析中,潜热的影响不是总可以忽略的,其误差取决于材料在物相转变时交界面温差的范围及材料熔解体积的大小.与不考虑相变潜热的情况相比较,考虑相变潜热时显示出较低的最高温度、较小的熔池范围和较窄的热影响区.通过对铍材焊接温度场、焊缝断面形状模拟结果与实际热循环曲线以及焊接接头形状的对比,表明,考虑潜热的计算模型会得出更精确的结果. 相似文献
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Deng-Kui Zhang Guo-Qing Wang Ai-Ping Wu Ji-Guo Shan Yue Zhao Tian-Yi Zhao Dan-Yang Meng Jian-Ling Song Zhong-Ping Zhang 《金属学报(英文版)》2019,32(6):684-694
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. 相似文献
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After nearly two years'tense construction the first phase of industrialized base of Shenyang Research Institute of Foundry 《中国铸造》2008,5(1):63-64
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. 相似文献
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Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
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. 相似文献
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R. González-Martínez 《金属学报(英文版)》2007,20(4):235-240
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. 相似文献
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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). 相似文献
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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. 相似文献
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B.W. Zhang B.W. Li 《金属学报(英文版)》2007,20(2):129-138
On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes' collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process. 相似文献
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R.Z. Wu Z.K. Qu B.D. Sun D. Shu J. Wang 《金属学报(英文版)》2007,20(3):193-198
The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results. 相似文献
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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. 相似文献
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Chao Yang He-Fei Huang Massey de los Reyes Long Yan Xing-Tai Zhou Tian Xia De-Liang Zhang 《金属学报(英文版)》2015,28(7):809
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. 相似文献