Neutralization process of Xe^q＋ ion grazing on Al（111） surface

A code has been developed to simulate the neutralization and grazing process of slow highly charged ion Xe^q＋ on Al（111） surface under the classical-over-the-barrier model. The image energy gain of Xeq＋ ions are calculated and compared with experiment data. The simulation results of image energy gain are in good agreement with the experiment data. Meanwhile, in the present work, the reflection coefficient of incident Xe^q＋ on Al（111） surface as a function of the incidence angle, energy and charge state is also studied.     

Solidified floating organic drop microextraction in tandem with syringe membrane miro-solid phase extraction for sequential detection of thallium (III) and thallium (I) by graphite furnace atomic absorption spectrometry

In the present study, a novel method based on solidified floating organic drop microextraction (SFODME) combined with syringe membrane micro-solid phase extraction (SMMSPE) was proposed for the sequential separation and enrichment of Tl(III) and Tl(I) followed by graphite furnace atomic absorption spectrometry detection. In SFODME, Tl(III) can react with 1-(2-Pyridylazo)-2-naphthol at pH 8.0 to form the complexes which can be extracted into an organic drop, while Tl(I) was remained in the solution. In SMMSPE, flexible TiO₂@SiO₂ nanofiber membrane was used as the sorbent for the enrichment of Tl(I) in the sample solution after the separation of Tl(III). This method did not require tedious pre-oxidation/pre-reduction operation and time-consuming centrifugation/filtration steps, which may cause sample contamination and analysis errors. Main parameters influencing the separation and enrichment of the target species were studied. Under the selected conditions, the detection limits for this method were 1.7 and 2.6 ng/L for Tl(III) and Tl(I) with relative standard deviations of 6.1 % and 5.2 %, respectively. This method was successfully used for the determination of the target species in environmental water samples and two certified reference materials. The determined values were in good agreement with the certified values.     

预混式双流体静电喷嘴喷雾特性及荷电性能

为实现高湿环境下脱硫塔内复杂烟气的高效除尘,设计了一种预混式双流体静电雾化喷嘴,并对其喷雾特性及荷电性能进行了试验研究。试验测量了喷雾粒径、锥角和荷质比等参数,通过量纲分析,得到了该喷嘴粒径分布与雷诺数Re的数学模型。试验结果表明:喷雾粒径随气液比(GLR)的增加呈指数减小,当气液比小于0.1时,喷雾粒径随气液比增加迅速减小,当气液比大于0.1时,喷雾粒径减小幅度趋于平缓;喷雾粒径随雷诺数的增加呈线性减小。喷雾锥角随着气液比增加呈先增大后减小的趋势,当气液比为0.1时喷雾锥角最大。气液比增加,喷雾荷质比增加,荷电效果逐渐增强。荷电电压的升高使得喷雾的单分散性提高,弥散空间逐渐增加。     

E‐MALDI: optimized conditions during electrowetting‐enhanced drop drying for MALDI‐MS

We recently showed that electrowetting‐enhanced sample preparation for MALDI‐MS (eMALDI) can increase the intensity of the MALDI signal by 2–25 times compared with conventional drop drying by concentrating all the dried sample in a single spot rather than leaving behind a heterogeneous coffee‐stain pattern. Here, we demonstrate that the eMALDI signal enhancement can be further increased to more than 100 times by systematically optimizing the electrowetting actuation frequency and amplitude. This enables 30 times signal increase for a peptide standard. Simultaneously, drop drying times can be reduced approximately five times by increasing the actuation voltage and/or decreasing the initial drop volume. Copyright © 2017 John Wiley & Sons, Ltd.     

Application of the Density-Functional Method for Numerical Simulation of Flows of Multispecies Multiphase Mixtures

Numerical examples of application of the density functional used to describe isothermal flows of two-phase two-species mixtures are given. The following flows are calculated in a two-dimensional formulation: impact of a drop on a liquid layer, breakdown of a drop in the velocity field of the Couette flow, formation of the wetting angle of a drop on a solid surface, and development of the Rayleigh–Taylor and Kelvin–Helmholtz instabilities at the gas–liquid interface.     

Leaky Tap Behavior Described by a Simple Discrete Mapping

The complex variety of phenomena associated with the dynamical behavior of a dripping faucet is reproduced with a simple map deduced from a one-dimensional analog mass-on-spring simulation, which has a dependence on a reduced number of parameters. It is analyzed how the dynamics of the real tap depends on the flow rate and on the geometrical parameters of the tip. Experimental bifurcation diagrams and attractors illustrate the adherence of the mapping to the real dynamics. The enormous simplifications in reducing the actual physical system to a simple oscillator mapping allows to us to investigate more deeply the parameter space and to understand the most important dynamical mechanisms of the leaky tap.     

Numerical simulation of drop migration in channell flow under zero-gravity

The migration of deformable drops in the channel flow neglecting the gravity influence is investigated numerically by solving the incompressible Navier-Stokes equations using the finitedifference method coupled with the front-tracking technique. The objectives of this study are to examine the effectiveness of the present approach for predicting the migration of drops in a shear flow and to investigate the behavior of the drop migration in the channel flow under zero-gravity. To validate the present calculation, some typical results are compared with available computational and theoretical data, which confirms that the present approach is reliable in predicting the drop migration. With respect to the drop migration in the channel flow at finite Reynolds numbers, the drops either move to an equilibrium lateral position or undergo an oscillatory motion under different conditions. The effects of some typical parameters, e.g., the Reynolds number, the Weber number, the viscosity ratio and the density ratio of the drop fluid to the suspending medium, and the drop size, on the migration of drops are discussed and analyzed. The project supported by the National Natural Science Foundation of China (10125210) and the Hundred-Talent Programme of the Chinese Academy of Sciences     

垂直上升管内油—气—水三相弹状流压力降的研究

给出一种垂直上升油－气－水三相弹状流压力降的计算模型。该模型考虑弹状流中Ｔａｙｌｏｒ气泡周围下降液膜的变化历程。通过油－气－水弹状流的实验研究发现，该模型的数值模拟结果与低压工况下的实验值符合得较好。本模型是计算垂直油－气－水三相弹状流中液相的连续相为水相时的压力降的有效方法。     

Two-phase pressure drop in multiple thick- and thin-orifice plates

Two-phase flow pressure changes through singularities such as sudden expansion and sudden contraction of thick- and thin-orifice plates were modeled. The modeling was based on the reversible and irreversible losses through contractions and expansions. The volume-averaged momentum equation and the reversible mechanical energy equation were used to evaluate the irreversibilities. Local slip ratios, which were necessary for the prediction of pressure drop through these singularities, were correlated from a large number of experimental data. To check the validity of the analytical predictions, an experimental test section was designed, and experiments were performed to produce benchmark pressure-drop data for thin- and thick-plate orifices. The working fluid used for these experiments was R-113. The predictive methods developed agree well with the experiments by the authors and with a wide range of two-phase flow test results obtained by others for steam-water systems. A parametric study shows the relative importance of geometry and of the flow variables such as quality, liquid-to-vapor density, and viscosity ratios on the pressure drop multipliers conventionally used in two-phase flows.     

Experimental study of flow and heat transfer in rib-roughened rectangular channels

Secondary flow patterns, pressure drop and heat transfer in rib-roughened rectangular channels have been investigated. The aspect ratio of the channels is 1–8, and ribs are attached to the wide channel walls in order to set up swirling motions. The geometries tested consist of channels having cross ribs, parallel ribs, cross V-ribs, parallel V-ribs, and multiple V-ribs (Swirl Flow Tube). The flow patterns were investigated using smoke wire visualization and LDV measurements. The smoke wire experiments have been performed at Re=1100 and the LDV measurements at Re=3000 at periodic fully developed conditions. The heat transfer and pressure drop are described by j and f factors for Reynolds numbers from 500 to 15 000. The distributions of axial mean velocity and turbulent fluctuations are strongly influenced by the secondary flows. Large mean velocities and small fluctuations are found in regions where the secondary flow is directed towards a surface, while small mean velocities and large fluctuations are found in regions where the secondary flow is directed away from a surface. The Swirl Flow Tube provides a significant increase in the j factor at Reynolds numbers from 1000 to 2000, but unfortunately also an increase in the f factor. At higher Reynolds numbers, the j and f factors of the Swirl Flow Tube are of the same order of magnitude as for the other rib-roughened channels. It is found that the flow direction in a channel with parallel V-ribs has important influence on the j/f ratio. At Reynolds numbers above 4000, this channel provides the highest j/f ratio if the V-ribs are pointing upstream; while it provides the lowest j/f ratio of all rib configurations, if the V-ribs are pointing downstream.