排气端面间隙对平衡式双螺杆压缩机流场特性影响的分析与研究

针对排气端面间隙对平衡式双螺杆压缩机内部流场特性的干扰问题,基于SCORG软件和PRO/E软件相结合的方法构建可充分考虑实际排气端面间隙的压缩机流体模型并对其进行高质量代数网格划分。在此基础上,运用CFX软件对3种不同尺寸排气端面间隙的平衡式双螺杆压缩机流体模型进行内部流场特性的精确数值分析,得到了流场压力分布、速度分布以及排气压力脉动随排气端面间隙间的变化关系。所得结果可为平衡式双螺杆压缩机间隙优化设计及工程应用提供重要理论支撑,对平衡式双螺杆压缩机结构及性能的优化研究具有重要参考意义。     

基于啮合接触线加载负荷下双吸平衡式双螺杆压缩机轴向力的算法

针对双螺杆压缩机螺杆转子轴向力计算过程复杂且效率低的问题,在通过实例计算验证了基于啮合接触线加载负荷法与经典法计算精度十分接近的前提下,给出了基于啮合接触线加载负荷下的双吸平衡式双螺杆压缩机轴向力算法实例,强调了此法的有效性。     

平衡式双螺杆压缩机数值模型构建与数值模拟

双螺杆压缩机是工业领域中可燃气等介质回收输送的主流装置。针对使用中的双螺杆压缩机转子单向受力的不足,提出一种可实现工作负载相向配置的平衡式双螺杆压缩机。为研究其工作过程中内部流场特性,基于平衡式双螺杆压缩机工作原理及基本结构建立了其流体数值模型,利用CFD技术,采用SIMPLEC算法及RNG/κ-ε湍流模型对其工作过程进行了数值模拟,得到了平衡式双螺杆压缩机工作过程中流体压力、速度以及密度的分布情况,为平衡式双螺杆压缩机工程应用提供参考。     

流热固耦合下的双螺杆压缩机转子结构特性研究

针对双螺杆压缩机工作过程中转子的结构特性问题,综合考虑压缩机产生的压力场和温度场,对螺杆转子进行流热固耦合研究。通过有限体积法求解压缩机工作过程中产生的压力场和温度场,采用数值插值技术将其加载到转子的结构网格上,建立转子的真实受力模型。进一步求解转子的静平衡方程得到转子的位移场和应力分布,并利用L形大直径掩埋管道对所提出的方法进行验证。研究结果表明:温度场是螺杆转子产生较大变形和应力的主要原因,选择合适的转速可以降低转子的变形和应力。研究结果对压缩机的结构设计和优化有一定的理论意义。     

某型号双螺杆压缩机流场分析及试验验证

针对双螺杆压缩机内部流体域结构复杂且呈周期性变化的特点,提出一种针对5~6齿双螺杆压缩机流场仿真研究的方法。该方法利用Scorg和Pumplinx软件联合对双螺杆压缩机流场进行仿真分析,避免了出现动网格负体积现象,解决了通过编写复杂的UDF函数定义阴、阳旋转方式的难题。仿真分析结果表明:作用于转子上的流体压力从进气口到出气口沿着轴线方向呈逐渐递增趋势,压力较高的压缩、排气域与压力较低的吸气域以接触线为界限两侧分布,压力呈波动性变化;温度变化呈非稳态特性,越靠近排气口变化越剧烈。通过试验的方式对双螺杆压缩机出口温度、压力的变化进行测试,试验结果表明,仿真数据与试验数据吻合度较好。因此,该仿真方法为螺杆压缩机的设计与深入研究提供了参考。     

平衡式双螺杆压缩机支承结构设计

基于平衡式双螺杆压缩机的技术特点及工作要求,提出一种充分体现其轴向力平衡为优势结构特征的平衡式双螺杆压缩机支撑件的结构形式,并根据阴阳转子受力分析的状态数据给出支承件负载计算方法与算式,可为平衡式双螺杆压缩机支承件的精确设计及其性能的再优化提供理论依据。     

双吸平衡式双螺杆压缩机流致噪声分析

双吸平衡式双螺杆压缩机采用对称结构,能够大幅降低机械噪声,从而流致噪声成为主要的噪声。为了研究双吸平衡式双螺杆压缩机内部流体噪声的具体声压级分布,提出利用CFX计算得到双吸平衡式螺杆压缩机的瞬态流场,再将结果进行离散傅里叶变换,运用Actran计算流致噪声。分析计算结果发现:压缩机的噪声频率声压级与压缩机的排气频率及其倍频相关;压力脉动变化率越大声压级越大;转子区域的声压级大于排气区域,排气区域大于进气区域;不同于其他压缩机,双螺杆压缩机的高频声压级仍然较大。     

齿顶及齿间间隙对双螺杆压缩机转子结构特性的影响

为研究间隙对双螺杆压缩机螺杆转子结构特性的影响及避免转子发生干涉与磨损现象，针对双螺杆压缩机中齿顶间隙和齿间间隙对螺杆转子结构特性的影响进行数值模拟分析。结果表明：随着齿顶间隙和齿间间隙的增大，阴、阳转子的最大变形呈现先增大后减小的趋势，但其变化范围较小；随着齿间间隙的增大阴阳转子的最大应力总体呈现增大的趋势，随着齿顶间隙的增大阴阳转子的最大应力趋于不变；当齿顶间隙大于或等于0.17 mm、齿间间隙大于或等于0.33 mm时，能够避免因转子变形发生干涉与磨损问题。     

栅格法三维六面体网格自动生成算法与优化

提出了以栅格法六面体网格生成为基础方法,基于实体模型几何特征的六面体网格自适应生成算法,首先对模型进行识别,根据实体模型几何特征建立加密源点信息场,并进行相容性控制,采用栅格法生成核心网格,然后进行核心网格与模型边界的拟合,为克服该方法在实体模型表面网格质量较差的缺点,采用节点位置平滑和拓扑关系优化对网格质量进行优化,生成质量较高的六面体网格。网格划分实例表明,该方法实用性强,效果良好。     

金属塑性成形有限元六面体网格自动划分

六面体网格具有计算精度高、网格数量少等特点 ,是工程三维有限元分析一种重要网格。本文提出了一种基于栅格的六面体网格自动划分方法 ,它首先采用栅格法生成核心网格 ,然后把核心网格与模型边界拟合 ,为克服由于边界拟合造成的表面网格质量下降 ,采用包络表面网格的方法生成零厚度表层网格 ,通过表面网格平滑和内部节点位置平滑处理 ,最终生成具有较高质量的全六面体网格。网格划分实例说明 :该法具有原理简单 ,算法可靠 ,编程方便 ,划分网格质量高等特点。最后还对该算法进行了讨论。     

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.     

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。     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

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.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

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.     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.