直流平面电磁泵流槽结构的实验研究

目的 研究直流平面电磁泵流槽结构与静压头的关系和相对效率 .方法 在以水银为传输介质的模拟直流平面电磁泵上进行实验 ,测量不同流槽结构在相同工作参数下静压头的大小 ;并以理论计算值为1 0 0 %的效率 ,计算了不同流槽结构的相对效率 .结果 不同结构的流槽 ,在相同工作参数下产生的静压头不同 ,相对效率有很大的差别 .结论 电磁泵的流槽结构对电磁泵的压头及相对效率有显著影响 .抑制工作电流的漫流 ,优化电力线方向 ,尽可能减小流槽腔体表面积 。

Analysis of Turbulence Structure in the Stirred Tank with a Deep Hollow Blade Disc Turbine by Time-resolved PIV

The turbulence structure in the stirred tank with a deep hollow blade(semi-ellispe) disc turbine(HEDT) was investigated by using time-resolved particle image velocimetry(TRPIV) and traditional PIV.In the stirred tank,the turbulence generated by blade passage includes the periodic components and the random turbulent ones.Traditional PIV with angle-resolved measurement and TRPIV with wavelet analysis were both used to obtain the random turbulent kinetic energy as a comparison.The wavelet analysis method was successfully used in this work to separate the random turbulent kinetic energy.The distributions of the periodic kinetic energy and the random turbulent kinetic energy were obtained.In the impeller region,the averaged random turbulent kinetic energy was about 2.6 times of the averaged periodic one.The kinetic energies at different wavelet scales from a6 to d1 were also calculated and compared.TRPIV was used to record the sequence of instantaneous velocity in the impeller stream.The evolution of the impeller stream was observed clearly and the sequence of the vorticity field was also obtained for the identification of vortices.The slope of the energy spectrum was approximately-5/3 in high frequency representing the existence of inertial subrange and some isotropic properties in stirred tank.From the power spectral density(PSD) ,one peak existed evidently,which was located at f0(blade passage frequency) generated by the blade passage.

Optimization of Channel Structure of Alkaline Water Electrolyzer by Using an Expanded Mesh as a Bipolar Plate

Alkaline water electrolysis(AWE)is the most mature technology for hydrogen production by water electrolysis.Alkaline water electrolyzer consists of multiple electrolysis cells,and a single cell consists of a diaphragm,electrodes,bipolar plates and end plates,etc.The existing industrial bipolar plate channel is concave-convex structure,which is manufactured by complicated and high-cost mold punching.This structure still results in uneven electrolyte flow and low current density in the electrolytic cell,further increasing in energy consumption and cost of AWE.Thereby,in this article,the electrochemical and flow model is firstly constructed,based on the existing industrial concave and convex flow channel structure of bipolar plate,to study the current density,electrolyte flow and bubble distribution in the electrolysis cell.The reliability of the model was verified by comparison with experimental data in literature.Among which,the electrochemical current density affects the bubble yield,on the other hand,the generated bubbles cover the electrode surface,affecting the active specific surface area and ohmic resistance,which in turn affects the electrochemical reaction.The result indicates that the flow velocity near the bottom of the concave ball approaches zero,while the flow velocity on the convex ball surface is significantly higher.Additionally,vortices are observed within the flow channel structure,leading to an uneven distribution of electrolyte.Next,modelling is used to optimize the bipolar plate structure of AWE by simulating the electrochemistry and fluid flow performances of four kinds of structures,namely,concave and convex,rhombus,wedge and expanded mesh,in the bipolar plate of alkaline water electrolyzer.The results show that the expanded mesh channel structure has the largest current density of 3330 A/m^(2)and electrolyte flow velocity of 0.507 m/s in the electrolytic cell.Under the same current density,the electrolytic cell with the expanded mesh runner structure has the smallest potential and energy consumption.This work provides a useful guide for the comprehensive understanding and optimization of channel structures,and a theoretical basis for the design of large-scale electrolyzer.

Corrosion resistance and cytocompatibility of Ti-20Zr-10Nb-4Ta alloy surface modified by a focused fiber laser

The corrosion resistance and cytocompatibility of Ti-20 Zr-10 Nb-4 Ta（TZNT） alloy modified by surface laser treatment were investigated. The scanning electron microscopy（SEM） measurements indicated that laser treatment on TZNT alloy generated groove morphologies with the width of^40 μm and the depth of ~10 μm on the surface. The water contact angles along the groove direction decreased by 51%compared with that of the untreated alloy. The laser treatment promoted the oxidation of metallic Ti, Zr and Nb and produced more stable oxides on surface. The corrosion potential increased by 50% and corrosion current density decreased by72% compared with that of the untreated alloy in the anodic polarization test for the alloy in Hank’s solution at 37°C. This indicated the improvement of the corrosion resistance by laser treatment. The cytotoxicity testing results showed that the laser-treated TZNT alloy performed similar MC3 T3-E1 cell viability compared with the untreated alloy. The cells displayed oriented growth along the groove direction due to the increased hydrophilicity. This novel material may be a new candidate in orthopedics and dentistry implantations fields.