An experimental investigation of the convective instability of a jet

This paper is an experimental study of the convective instability of a jet. It is well known that a jet issuing forth from a nozzle is unstable due to surface tension forces that cause it to break downstream into drops. We apply a disturbance of a given frequency at the nozzle tip. This applied frequency determines the wavelength and the growth rate of the growing disturbances and, thereby, the drop size. We measure the wavelength and the growth rate by fitting the entire digitized image of a jet to the functional form suggested by the linear theory. Thus, it makes use of the entire profile instead of the small number of points used in previous studies. Also, in contrast to previous work, we independently measure the jet velocity and the wave speed. At high non-dimensional jet velocity, the experimental results for the growth rates and the wave numbers agree with the linear stability theory of an infinite jet in the absence of gravity. At very low velocity (low Froude number) gravity is important and the agreement is not good.     

An experimental investigation of interfacial instability in separated blood

Experiments are done with separated human blood decelerated at constant rates to determine the maximum deceleration rate while avoiding remixing of the layers, which have different densities and viscosities. The deceleration rate affects both the stability and separation of particles through sedimentation. The velocity at onset of instability for a constant deceleration rate is experimentally determined for a 12-cm-diameter disk. Parameters of cell pack thickness, plasma thickness, and total thickness are investigated experimentally, and the only statistically significant parameter to affect stability is rate of deceleration. The data describe a correlation separating regions of stability and instability. To understand stability in decelerating flow of separated blood plasma and cells, the equations of motion are solved for a two-layer fluid flow with a moving boundary and free surface. Inclusion of non-Newtonian rheology of blood predicts large discontinuities in the shear rate, which is proposed as the cause of the interfacial instabilities. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1376–1386, 2019     

水性木器涂料施工方式浅论

总结归纳了各具特色的9种水性木器涂料的施工方式和工艺,包括刷涂、喷涂、擦涂、浸涂、滚涂、辊涂、淋涂、静电喷涂和美式涂装,探讨了在不同的木头材质、涂膜要求、施工环境和工件形状的条件下,应如何选择不同的施工方式。     

竹木百页窗辊涂专用丙烯酸涂料的研发和应用

采用热塑性丙烯酸树脂搭配醋酸丁酸纤维素,制得具有快干、高透明度及优并耐候性的辊涂专用涂料,极大地提高了辊涂作业的效率。     

聚酯型网纹漆的制备及性能研究

以聚酯树脂为主体树脂,添加辅助树脂、网纹粉、网纹漆催化剂等组分,制备具有美术效果及相应漆膜性能的聚酯型网纹漆。对漆膜的纹路、T弯、MEK、冲击、水煮、耐候性能进行考察,结果表明,颜基比为0.3~0.6、氨基比为1/4~1/6、氨基树脂D、辅助树脂添加12%~14%、网纹漆催化剂添加7%~10%、网纹粉添加3%~5%、膜厚27μm、PMT 224℃的RAL9002网纹卷钢涂料具有良好的网纹效果。     

轿车漆膜抛光表面的原子力显微镜研究

用原子力显微镜技术研究了黑色金属漆漆膜表面在打磨抛光处理过程中,漆膜表面形貌在纳米尺度上的变化图象,跟踪了在抛光过程漆膜表面微观缺陷的变化,认为在漆膜抛光时发生在表面的摩擦过程导致漆膜表面微观形貌变化,大量的微观裂纹的出现及在抛光过程中的亚微观缺陷尺寸的变化,对漆膜表面特征有一定影响。     

挖掘机结构件涂装工艺技术比较分析

主要介绍了挖掘机结构件合线涂装与分线涂装两种方式的涂装工艺及工艺设计参数,并就工艺线路布置、输送方式、设备、人员、能耗及经济性作了比较分析。     

Ni-P化学镀层换热器应用动向

化学镀Ｎｉ－Ｐ镀层换热器在石化行业近年得到一定的工业应用,但由于工艺控制等原因,镀层具有孔隙,影响使用,采用镀后化学处理及涂数有机涂层等,能使换热器是一步提高。     

精密涂布工艺应用新进展

精密涂布工艺在功能性薄膜生产中起着重要作用。当今材料工业的迅速发展,对涂层提出更薄、更均匀的要求。特别象平板显示器(FPD)中所用的功能性光学薄膜,如防反射膜、防眩光膜等,其涂层厚度往往小于1μm。另外,锂电池电极的涂层则要求采用间歇式涂布方法来生产。本文着重介绍了近年来微凹版涂布和条缝涂布工艺在平板显示器、有机发光二极管(OLED)、锂电池行业中应用的新进展。     

改性环氧带锈涂料的研究

研究了以改性环氧树脂和聚乙烯醇缩丁醛为基料的钢铁带锈涂料 ,通过对成膜物质、转化剂、渗透剂、颜料等的研究 ,得到了集稳定、转化、渗透为一体的多功能涂料。经过实验测试 ,该涂料的各项性能指标均达到了设计要求 ,并且本工艺方案简单易行、省时高效 ,具有较高的实用价值。     

从目前我国涂料产业与市场的新变化看其未来对策选择

介绍了我国涂料产业和涂料市场的新变化及其未来发展趋势。     

Prediction of macromolecular transport through the deformable porous media of an artery wall by pore theory

To determine the transport properties of macromolecules in the media of an artery wall deformed inhomogeneously by the transmural pressure, we combine a simple mechano-hydraulic model based on a two parameter strain-dependent permeability function, which was developed by Klanchar and Tarbell [1987], with a pore theory. The combined theory allows us to calculate the spatial distributions of porosity, solute partition, pore radius and macromolecuiar solute concentration in the media and their dependence on the transmural pressure. The predictions from the pore theory are in good agreement with experimental measurements of sucrose space, albumin space and albumin concentration profiles in the media of rabbit aortas at transmural pressures of 70 and 180 mmHg. The prediction indicates that albumin transport through the aortic media is dominated by convection rather than diffusion. It is further demonstrated that the transport properties of planar tissue samples, which are often used inin vitro experimentais, may be quile different from those of intact vessels in their natural cylindrical configuration because of the variation in tissue deformation. Using the pore theory we are also able to calculate the interstitial shear stress associated with transmural volume flow which may act on the smooth muscle cells residing in the media and find it to be on the order of several dyne/cm². This level of shear stress will stimulate endothelial cells and may also affect smooth muscle cells.     

粉末涂料的静电涂装技术

粉末喷涂的喷涂效果在机械强度、附着力、耐腐蚀、耐老化等方面优于喷漆工艺,成本也在同效果的喷漆之下。针对粉末涂料的静电涂装及其前景和发展空间,分析了粉末涂料静电涂装的特点及技术要求,阐述了静电粉末喷涂的工作原理,介绍了粉末静电喷涂的基本原料及主要设备,提出了粉末静电喷涂工艺及施工要求,同时指出了粉末静电喷涂作业的常见问题及处理方法。     

Methanol synthesis under periodic operation: An experimental investigation

Experiments have been conducted on Cu/ZnO and Cu/ZnO/Al₂O₃ catalysts at 225°C and 2.86 MPa in an isothermal, differential packed bed reactor to identify promising periodic operations strategies and find cycling variables which give the largest improvement in the synthesis rate relative to steady state. Modulating the H₂ and CO₂ concentrations appears to be the best strategy. However, the increased rate under composition modulation was insensitive to cycle period, amplitude and split in the cycle period range from 2 to 30 min. Higher methanol yield resulted from the suppression of the reverse water gas shift reaction. Higher rates under cycling arise from structural or compositional changes to the catalyst surface.     

15万套塑料件涂装线的工艺探究

介绍了具有15万套塑料件涂装能力的涂装线及其涂装工艺。     

聚氨酯粉末涂料的研制与涂膜影响因素分析

运用正交试验法，确定制备聚氨酯粉末涂料的挤出机工艺参数，进行了树脂/固化剂摩尔比、固化催化剂含量、固化时间和温度等条件对涂膜性能的影响的研究，从而得到较为理想的条件。     

粉末涂料制造工艺及其技术研究进展

本文从粉末涂料的制造、涂装的原理分析了其在涂料领域中的优势，探讨了粉末涂料的发展前景及技术发展趋势。     

复合电镀层应用的新动向

介绍了复合电镀层应用的新动向，如电解工业用电极的制备，铝发动机气缸的应用，重点介绍Sn-Ag纳米微粒复合镀层做为无铅可焊镀层的溶液，pH值，霍氏槽及可焊性试验的结果，还介绍了具有装饰和优良憎水性的镍－聚四氟乙烯微粒复合镀层，简述了其工艺过程，溶液组成和操作条件，镀层特性及应用。     

无铬锌铝涂层的研究进展研究

介绍了无铬锌铝涂层的工艺流程、防腐蚀机理、膜层性能特点,以及国内外研究概况和应用领域,并对无铬锌铝涂层技术的发展提出了展望。