水力旋流器结构与分离性能研究（六）：柱段结构（长度）

研究了水力旋流器主段长度对其分离性能的影响，结果表明，随着柱段长度的增大，水力旋流器处理能力呈单调上升趋势，其分离修正总效率呈上升趋势，其溢流浓度则呈单调减小趋势，在水力旋流器用于固液分离场合时，其柱段长度宜较长为佳。     

水力旋流器分离空间匹配优化研究

首次系统地研究了水力旋流器分离空间匹配系数对其分离性能和能量耗损等方面的影响，结果表明，随着柱锥空间比值的增大，分离修正总效率上升，能耗系数降低，分离粒度和分离精度则呈二次曲线形变化。最后给出了适应不同场合要求的水力旋流器的最佳分离空间匹配系数和圆筒段长度推荐值。     

油水分离水力旋流器锥段长度对速度场影响研究

油水分离水力旋流器锥段长度对旋流器的性能影响非常巨大,用CFD计算方法对旋流器通过运用雷诺切应力RSM湍流模型与代数滑移应力ASM,基于欧拉法的Mixture两相流模型进行模拟分析。得到大小锥段长度变化对两锥段的轴向与切向速度影响,结果表明旋流器内旋流轴向速度对大、小锥段长度均敏感,外旋流切向速度对大锥段长度敏感。研究结果为优化旋流器结构与设计提供参考．     

基于响应面法的水力旋流器结构参数优化

为了进一步增强水力旋流器的分离性能,采用响应面优化方法(Response Surface Methodology,RSM)对同向出流水力旋流器的结构参数进行优化,寻优范围为大锥段长度在51.3～62.7mm、小锥段长度在120.6～147.4mm、出水管长度在90～110mm内,构建了区域内结构参数对旋流器底流口含油浓度影响的数学关系模型,并获取了最佳结构参数。开展数值模拟和室内实验,对优化后旋流器的分离性能进行验证,结果显示,优化后的旋流器结构较原始结构可将分离效率提高4.45%,实验值与模拟值呈现出了较好的一致性,充分验证了优化结果的准确性。     

低砷磷生产工艺中分相器的优化技术研究

通过建立计算流体力学模型,采用Fluent软件,选用雷诺应力模型(RSM模型)作为湍流模型对该工艺中的液-液旋流分相器进行流体力学数值模拟,通过数值模拟仿真优化旋流器的各结构参数,同时研究不同操作参数和物性参数对旋流器分离效率的影响,并在此基础上进行结构参数的优化.模拟结果表明,溢流口直径为30 mm,溢流管伸入长度为60 mm,圆柱段长度为80 mm时旋流器分离效率最佳.     

水力旋流器分离性能强化研究

设计了一种在旋流器轴心线位置具有中心固棒的新型水力旋流器,该中心固棒的引入有效地消除了旋流器内的中心空气柱。实验研究了该中心固棒替代空气柱对旋流器性能指标的系统影响。研究结果表明,采用中心固体棒取消旋流器内的空气柱后,旋流器的分离性能得到了有效的强化。与具有空气柱的旋流器相比,不管旋流器锥段结构如何变化(从普通直锥、到抛物线型锥、到双曲线型锥),具有中心固棒的旋流器均具有更高的分离总效率、更高的修正分离总效率、更小的修正分离粒度以及更高的分离精度。随着旋流器锥段内部空间的增大,中心固棒使旋流器分离性能提高的幅度也增大。     

钢筋玄武岩纤维混凝土短柱轴心受压承载能力试验研究

为了研究玄武岩纤维对钢筋混凝土受压构件中增强功能,推进玄武纤维的应用,本文首先对添加0.1%体积掺量的5种长度玄武岩纤维混凝土进行纤维最佳长度研究;得到最佳长度为12 mm玄武岩纤维对混凝土立方体强度增强效果最佳;其次选择12 mm和24 mm的两种玄武岩纤维混凝土最佳掺量进行研究,得到最佳掺量0.15%.在此基础上,本文以体积掺量0.15%,长度为12 mm和24 mm玄武岩纤维混凝土各制作了3根钢筋玄武岩纤维短柱,制作普通钢筋混凝土短柱3根,并对所有试验柱进行了轴心受压极限承载力试验,结果发现,钢筋玄武岩纤维混凝土短柱的轴心受压极限承载能力较普通钢筋混凝土柱最大提高了28%;玄武岩纤维提高了钢筋混凝土短柱的延性.另外,钢筋玄武岩纤维混凝土短柱轴心受压极限承载力试验值大于理论计算值,说明玄武岩纤维不仅提高了混凝土抗压性能,也提高了钢筋和混凝土共同作用效能.     

锥段长度对微型旋流分离器内流场影响的数值模拟

采用CFD软件FLUENT对3种不同锥段长度的微型旋流分离器中的液相流动规律进行数值模拟.模拟结果表明,随着旋流器锥体长度的增加,旋流器内切向速度降低,径向速度减小,轴向速度增大,压降减小,分流比增大.适当加长旋流器长度可获得较佳的分离性能,然而过分增加旋流器长度,分离性能反而会降低.     

压载水旋流器结构因素对分离性能影响分析

随着全球贸易和船舶运输的发展,压载水对环境的影响越来越大。水力旋流分离设备是压载水净化的重要固液分离设备。本文使用计算流体力学,建立数学模型模拟压载水旋流分离过程,模型包括多相湍流雷诺应力模型RSM、处理气液界面的自由表面多相流动模型VOF、处理固体颗粒运动规律的离散相模型DPM。通过数值模拟计算柱段长度、底流口直径和溢流口直径这几个关键因素对旋流器内部流场和分离效率的影响,获得了各个因素对分离效率的影响规律：柱段长度变化对旋流器分离效率的影响不大;底流口直径对旋流器压力降的影响不明显,但对分流比的作用比较大;溢流管直径的增大有助于降低能耗和增大溢流口流量,但随着溢流管直径的增大,分级粒度变大。这些规律为高效旋流分离净化压载水奠定了基础。     

利用旋流器式浮选柱分选煤泥

本文简要介绍旋流器式浮选柱结构和工作过程，并通过几个代表性煤样的分选试验，分析归纳了该浮选柱的性能及特点。     

On the length of statistical segment in flows of polymers

This paper presents a simple statistical model for calculations of the flow segment for polymer melts. The comparison of calculations with available data for five polymers demonstrates the model consistency. The model calculations show that the length of flow segment is generally more than the length of the Kuhn segment, and for high molecular weight polymers, the length of the flow segment is considerably less than the length of polymer chain between molecular entanglements. Our calculations also allowed for indirect evaluation of activation energies for monomer fluids, which are poorly determined from experimental data.     

Investigation on isothermal crystallization,melting behaviors,and spherulitic morphologies of multiblock copolymers containing poly(butylene succinate) and poly(1,2‐propylene succinate)

In this article, isothermal crystallization, melting behaviors, and spherulitic morphologies of high‐impact multiblock copolymers, comprising of PBS as hard segment and poly(1,2‐propylene succinate) (PPSu) as soft segment with hexamethylene diisocyanate as a chain extender, were investigated. The results from differential scanning calorimetry (DSC) suggest that the two segments of multiblock copolymers are miscible in amorphous region. The crystallization kinetics were analyzed by the Avrami equation. The effect of PBS segment length as well as the introduction of PPSu segment on the crystallization kinetics and melting bebaviors of block copolymers was studied. Both crystallization rate (G) and spherulitic growth rate (g) are markedly increased with the increase of PBS segment length or decreased with the incorporation of PPSu segment. All the multiblock copolymers show the multiple melting behaviors, whose position and area depend on PBS segment length and the presence of PPSu segment. The melting peaks shift to higher temperature region with increasing PBS segment length. Spherulitic morphologies of the multiblock copolymers after being isothermally crystallized were examined by polarized optical microscopy. It is the first time to investigate the effect of one segment length on crystallization bebavior of block copolymers based on a fixed weight ratio systematically. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

柱型水力旋流器筛分软木浆的评价

Pulp fiber length characterization is addressed in this article. It is .suggested that the proposed separation index H（L） is a viable index to the fiber fractionation performance for evaluating hydrocyclones. Fractionation of softwood （coniferous wood） bleached chemithermomechanical pulp （BCTMP） fiber was carried out with a cylindrical hydrocyclone. Pulp fiber length characteristics in different streams were examined using the fiber quality analyzer （FQA）, and the cumulative fiber length fraction, the fiber length fraction density function and the separation index H（L） for different streams were obtained. It is found that H（L） is very useful for characterizing the fiber fractionation performance by indicating the separation capacity of hydrocyclone for individual subgroup of fibers in different streams under different operation conditions. Results of H（L） show that there exists a critical fiber length. A higher proportion of fibers longer than the critical fiber length is in the overflow stream, and a higher proportion of fibers shorter than the critical fiber length in the undertow stream. The data obtained from FQA suggest that the split ratio is the most significant parameter for fiber fractionation performance, which is the best when the split ratio is in the range between 0.14 and 0.2. The effect of feed rate on fiber fractionation performance is weak.     

高固含量水性聚氨酯的合成及其成膜性能的研究

采用预聚体分散法制备出50%以上固含量的水性聚氨酯,考察了软链段分子链长及硬链段含量对聚氨酯相分离行为、热性能及力学性能等的影响。研究表明:硬链段含量、软链段链长的提高和离子基团的增加均有利于拉伸强度的提高。     

Packing of Cylindrical Particles with a Length Distribution

The packing of cylindrical particles with log-normal and modified power-law length distributions has been experimentally studied. The results indicate that the packing density is heavily dependent on the parameters in the two distributions. However, this dependence cannot be predicted by the direct analogy to that for the packing of spherical particles. It is postulated that the packing of nonspherical particles be governed by two factors: the shape effect and the size effect, which respectively correspond to the unmixing and mixing states of a particle mixture and are quantified from the specific volumes of the two states. Analysis of the results suggests that the shape effect is dominant for the packing of cylindrical particles with a wide length distribution.     

聚(对苯二甲酸丁二醇酯-co-ε-己内酯)的合成及表征

以聚对苯二甲酸丁二醇酯(PBT)和ε-己内酯(CL)为原料,通过PBT端羟基引发CL开环聚合,然后在高温、高真空条件下缩聚,制备了不同硬段含量的聚(对苯二甲酸丁二醇酯-co-ε-己内酯)共聚酯(PBT-CL)。通过1H NMR、IR、DSC对PBTCL进行了表征。结果表明PBT-CL具有嵌段聚合物特性。共聚酯的熔点随硬段含量升高而上升。硬段序列长度随硬段含量增加而增加,比通过单体法制备的共聚酯要长。     

Photostability of polyetherurethaneureas

Polyetherurethaneureas (PEUUs) were synthesised from polyethylene-glycols (PEGs) of molecular weight 400, 600 and 1000, 4,4′-diphenylmethanediisocyanate (MDI) and aliphatic diamine chain extenders, 1,3-propanediamine (PDA) and 1,6-hexanediamine (HDA). Polymer films were irradiated with 365 nm light at 293 K and the effects of polyether soft segment length and urea hard segment on photo-oxidative stability were studied by following the variation in weight-average molecular weight (M _w), gel formation and stress-strain properties. Changes in ultraviolet and infrared spectroscopy were monitored on photo-oxidation and hydroperoxide content determined. The soft segment length was increased by increasing the molecular weight of PEG from 400 to 1000 and hard segment structure was changed by variation of diamine. It was noted that the structure of urea and polyether soft segment length plays an important role in photostability of PEUUs. PDA chain extended PEUUs were more stable than HDA chain extended PEUUs.     

Dielectric properties of segmented polytetramethyleneoxide-based polyurethanes

Three series of segmented polyurethanes, based on polytetramethylene oxide (PTMO) soft segments, having molecular weights of 650, 1000, and 2000 and MDI/butane diol hard segments, were synthesized and their dielectric properties examined. The effect of the soft segment length, soft segment concentration (ssc) as structural variables, and frequency and temperature as experimental variables, on relative permittivity and tan δ, were examined. The results were discussed in terms of the structural parameters such as the degree of phase separation and soft segment phase state. It was found that both soft segment length and ssc strongly affect dielectric behavior.     

Tuning the properties of segmented polyurea by regulating soft‐segment length

Polyurea is being widely advocated as a “retrofit” coating on structures, which mandate protection against blast. The physical properties of polyurea can be tuned by judicious choice of reactants, and the processing methodology employed for its preparation. The purpose of this study is to establish the dependence of material properties on the soft segment length in polyurea. Polyurea formulations were prepared by reaction of commercially available isocyanate prepolymer with poly(propylene oxide) based amines of varying molecular weights (230–2000 g/mol). The effect of increasing the soft segment length on the mechanical properties of polyurea under both quasi‐static as well as dynamic conditions was determined. Ductility was found to increase proportionally with increasing soft segment length, with a concomitant decrease in the tensile strength. All the compositions exhibited sub‐ambient glass transition temperature, which was found to reduce with increasing soft‐segment length. Time–temperature superposition principle was used to arrive at master curves for all compositions. The frequency essential to initiate the process of dynamic “rubber to glass” transition was found to be directly proportional to the soft segment length. All the formulations were found to be capable of exhibiting an elastomeric response even under high frequencies typical of blast loadings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46284.     

热塑性聚酰胺酯的制备及结构性能关系

聚酰胺酯是一种由两种链段（硬、软段）组成的嵌段共聚物。其玻璃化转变温度（Ｔｇ），熔点（Ｔｍ），动态模量（Ｇ′）等与硬、软段的组成，含量紧密相关。硬段的链长分布影响其结晶结构从而影响其机械力学性能。先制备具有均一链长的含有酰胺键的硬段单体，然后与二元醇进行缩聚反应生成酯键是制备性能良好的聚酰胺酯的较好途径。