涡轮桨变速搅拌槽内湍流混合的实验研究

以NaCl颗粒在水中的溶解为例,对湍流状态下周期性变速旋转的（改变桨叶转向或速度大小,分别称为周期性换向搅拌和周期性依时搅拌）Rushton桨搅拌槽内的混合特性进行了实验研究,并与稳速搅拌进行了对比。实验过程中测量了不同搅拌模式、不同桨叶安装高度时颗粒的溶解时间,结果证明,搅拌槽底部的流型对NaCl的溶解有重要影响;桨叶安装高度对溶解速度的影响不大,周期性依时搅拌时的溶解时间比稳速搅拌时稍短,而周期性换向搅拌则能明显加快溶解速度,提高混合效率。     

超声波钢包精炼冷态模拟

以某钢厂180t钢包为原型,进行超声波改善钢包熔池搅拌效果的冷态模拟实验。通过记录pH计示数变化研究底吹气体搅拌均混时间及超声波搅拌均混时间。实验结果表明,在底吹空气水模实验中,当吹气位置在距离中心为0．33R,流量为0．1m3／h时,底吹气体搅拌所需的均混时间最短为50s;超声波水模实验中,当波源伸入钢包的中心液面下25cm处,输出功率1．8kw,均混时间最短为35s;在超声波和底吹气体联合实验中。当吹气位置在距离中心为0．33R,流量为0．1m^3／h,波源伸入钢包的中心液面下25cm处,输出功率1．8kw时,均混时间最短为48s;可以看出超声波可明显缩短钢包均混时间,改善钢包精炼动力学条件。     

Effects of viscosity ratio and composition on development of morphology in chaotic mixing of polymers

This study investigated the effects of viscosity ratio (p) and composition on morphology development in an immiscible polymer system mixed under chaotic flow conditions. It was seen that morphology of the dispersed phase developed through a widely accepted route involving transitions from lamellas to fibrils and to droplets. It was found in experiments with p≥1 that the dispersed phase converted into droplets very rapidly with narrow droplet size distribution when p∼1. For higher values of p, the speed of morphological transitions slowed down, the droplet size distribution became wider, and much larger droplets were formed. Similar effects were observed at higher concentration of the dispersed phase. No self-similar scaling behavior was observed in the droplet size distribution, which can be attributed to the lack of self-similarity in the breakup of lamellas into fibrils.     

Fabrication of a gradient refractive index preform using laminar shear mixing

A gradient refractive index rod was successfully prepared by a new fabrication method using laminar shear mixing, and a graded index polymer optical fiber that satisfied IEEE1394b was obtained from the method. To fabricate the gradient refractive index rod, a liquid monomer mixture with a relatively low refractive index was placed in a prepared cylindrical glass reactor and a transparent polymer rod with a higher refractive index was introduced at the center of the reactor. The reactor and the polymer rod were then rotated concurrently with a small rotating speed difference to generate a Couette flow in the liquid phase. The centrifugal force generated by rotation and the polymer diffusion into the liquid monomer mixture developed a graded concentration profile in a radial direction. The Couette flow could reduce the concentration fluctuation in a tangential direction. In addition, the graded index profile could be controlled by the copolymer composition of the rod and its diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1100–1104, 2005     

窄分布醇醚羧酸盐与常用表面活性剂复配性能

用氧化法合成的窄分布醇醚羧酸盐(NAEC9)与月桂醇醚硫酸铵(ALES)、十六烷基三甲基氯化铵(1631)、八/十烷基葡糖苷(APG0810)进行复配,研究了NAEC9不同质量分数对复配体系表面张力、泡沫性、润湿性、乳化性、去污性的影响。结果表明,窄分布NAEC9与1631复配后在表面张力、泡沫性、润湿、乳化性能上有明显的协同增效作用,且NAEC9质量分数为66.7%时协同作用最强,此时,润湿时间由不润湿降低至37 s,30s泡沫体积最大(500 mL)。而NAEC9与ALES、APG0810复配体系在性能上协同作用不显著。在去污性能上,NAEC9与ALES复配体系对皮脂污布去污性能最好,对蛋白污布去污能力最差。阴离子表面活性剂NAEC9与阳离子表面活性剂1631复配具有良好的协同作用,表面活性增强的同时不会产生沉淀。     

Investigation of Flow Patterns in Continuous‐flow Stirred Vessels by Laser Doppler Velocimetry

The flow structure of a continuous‐flow reactor stirred by a Rushton turbine was investigated by laser Doppler velocimetry for two different mean residence time‐mixing time ratios. Velocity measurements were obtained for two inlet locations, corresponding to the incoming liquid stream being fed co‐currently or counter‐currently to the flow discharged by the turbine. In all investigated configurations and for all operating conditions, it was found that the flow disruption caused by the incoming liquid stream was observable mainly in the first vessel quarter, which followed the feed‐tube plane. From comparison of the velocities encountered in the various planes in the continuous‐flow reactor to the velocities of the batch reactor, it was also concluded that it may be possible to intensify the usage of the turbine‐stirred vessel by decreasing the characteristic times ratio, without considerable flow by‐pass and/or short‐circuiting problems.     

混凝土行业中基于JCS的海量数据协同模块的研究

随着国内预拌混凝土行业的发展,混凝土企业高层越来越意识到搅拌站信息化管理的必要性,各种混凝土搅拌站ERP软件在国内得到了迅速的发展,通过这种软件的信息化管理,后台数据库每天都会产生大量的生产数据。为了避免搅拌站之间的恶性竞争,混凝土行业协会和政府部门需要对某个区域乃至整个行业的搅拌站的生产运营情况有实时的了解,以便对其进行监管,最终促进行业的公平竞争。本文结合国内混凝土行业自身的特点,阐述了混凝土行业海量数据协同的总体构想和数学模型,之后从多维度论述了基于JCS多级缓存的海量数据协同模块的设计,最后,采用Socket的方式最终实现了Server端与Client端的一对多的数据通信。     

立方型状态方程结合Eyring理论在液体混合物黏度计算中的应用

Cubic equations of state (EOS) have been combined with the absolute rate theory of Eyring to calculate viscosities of liquid mixtures. A modified Huron Vidal gE-mixing rule is employed in the calculation and in comparison with the van Laar and the Redlich-Kister-type mixing rule. The EOS method gives an accurate correlation of liquid viscosities with an overall average deviation less than 1% for 67 binary systems including aqueous solutions. It is also successful in extrapolating viscosity data over a certain temperature range using parameters obtained from the isotherm at a given temperature and in predicting viscosities of ternary solutions from binary parameters for either polar or associated systems.     

高粘度金属漆搅拌器流场数值模拟

金属漆粘度值高,含金属颗粒,长时间放置出现液体分层现象,影响配色准度。为对搅拌器内金属漆进行充分搅拌,使金属漆达到较高均匀度,采用k-ε湍流模型和多重参考系模型(MRF),基于CFD(计算流体动力学)技术对不同搅拌桨组合下的金属漆搅拌器进行数值模拟。数值模拟结果表明,上层搅拌桨选择错位45°折叶涡轮桨叶,下层搅拌桨选择错位平直桨叶的搅拌器搅拌桨组合,与普通双层平直桨叶搅拌器相比搅拌效果更好,混合效率提高20.99%。     

TTShuffle：一种区块链中基于两层洗牌的隐私保护机制

区块链隐私保护技术中的去中心化混币机制CoinJoin和CoinShuffle,分别因为代理节点不可信和节点需要层层传递加密而存在安全或效率低的问题,因此提出了TTShuffle,一种两层的隐私保护机制。首先将所有混币节点分成不同的组,通过层层加密在组内进行第一层洗牌,保护组内交易的敏感数据;然后由每个组派一个节点作为本组的代表,进行第二层的组间洗牌,保护所有组的敏感数据得到最后完整的交易内容。通过安全和实验分析表明,TTShuffle中40个混币参与者混币时间低于10 s,相比CoinShuffle机制提高了混币的效率,减少了混币时间,也确保了混币过程的隐私安全。