Development of a Flat‐Plate Cooling Device for Electronic Packaging

In this study, a microcapillary pumped loop (MCPL) that can be used as a cooling device for small electronic and telecommunications equipment has been developed. For thin devices such as an MCPL, securing a vapor flow space is a critical issue for enhancing the thermal performance. In this letter, such enhancement in thermal performance was accomplished by eliminating condensed droplets from the vapor line. By fabricating the grooves in the vapor line to eliminate droplets, a decrease in thermal resistance of about 63.7% was achieved.     

Scanning droplet cell investigations on single grains of a FeAlCr light weight ferritic steel

Polycrystalline Fe7.5Al7Cr is a ferritic light weight steel that shows a strong anisotropic dissolution behaviour. This electrochemical phenomenon was investigated by use of a scanning droplet cell (SDC). The crystallographic orientation of the single grains was determined by electron back scatter diffraction (EBSD). The fraction of grains with a near 〈1 1 1〉 orientation (<10°) was 1.88 times higher than that of the near 〈0 0 1〉 orientation prior to annealing and 3.58 times higher after annealing. Voltammograms were performed on single grains with low index planes. The critical current density was 53% higher on 〈0 0 1〉 grains as compared to 〈1 1 1〉 grains. These results are used to discuss the electrochemical behaviour of the polycrystalline FeAlCr.     

Prediction of the size distribution of secondary ejected droplets by crown splashing of droplets impinging on a solid wall

Crown splashing is frequently observed during the impact of a droplet on a rough or wet wall. The size distribution of secondary ejected droplets has been experimentally observed to satisfy the log–normal distribution which contains two free parameters: the most probable diameter d_s and the width of the distribution γ. The most probable diameter will be determined through a simplified physical analysis. The width of distribution will be determined by using the principle of maximum rate of entropy production. The theory, containing no free parameters, predicts known experimental results with an acceptable engineering accuracy, provided the Froude number is high enough.     

油/聚合物溶液体系动态界面扩张模量的测量

以十二烷为油相,以HPAMMo 4000(M=2.0×107,HD=24%)在0.5%NaCl盐水中的溶液为水相,用法国ITConcept公司的Tracker型全自动液滴界面张力仪在30℃测定了油水界面的动态扩张模量E。结果表明,初始滴体积V对E～t曲线无明显影响;固定V=20μL,E达到动态平衡值所需时间(振荡周期λ=10s)随水相聚合物浓度CP增大而缩短,E平衡值随CP增大而增大,随λ增大而略有减小,因此V,t,λ等测量参数均需采用实验方法确定。根据纯水表面张力测量值,此方法的实验误差为0.7%。介绍了测量原理。用此法测定胜利孤岛原油(70℃粘度52.9mPa·s)与0.75、1.0、1.5g/LMo 4000溶液间的E值,分别为16.4、17.8、21.4mN/m。图3表2参7。     

High data rate measurements of droplet dynamics in a vertical gas-liquid annular flow

Two-dimensional phase Doppler anemometry techniques have been used to achieve simultaneous measurement of the velocity and size of individual droplets entrained into the gas core during upward annular gas-liquid flow. Data rates greatly exceeding those of other experimental techniques have been achieved. Information is presented on the centreline variation of droplet velocity and droplet size, together with size and velocity correlations, for a range of flowrates and hydrodynamic development lengths from 135 to 228.     

Arc light sensing of droplet transfer in pulsed GMAW process and its mechanism

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Design and fabrication of medical micro-nebulizer

The application of a spray device to treat respiratory disease has long been known to be effective. Clinical studies have shown that the finer the droplet size, the deeper position of trachea that can be reached. With the aim of enhancing the curative effect, this study proposes a new design of micro-nebulizer, integrating a piezoelectric actuator, micro-nozzle plate, and the cavity of the micro pump to achieve a high-quality atomizing effect. In this research, we built a novel portable micro-nebulizer device with a changeable and cleanable medication chamber, which can generate a spray droplet of less than 4.04 μm in size (sauter mean diameters, SMD) and has a nebulizer rate of 0.5 ml/min. The device has an electrical requirement of drive voltage only 3 V, with a low power consumption of 1.2 W and an optimal operation frequency of 120 kHz. According to the simulations and experiments, it can be inferred that the droplet size distribution of the micro-nebulizer described in this research is finer and more uniform than that of the current conventional devices; furthermore, the system power consumption is lower than that of the ultrasonic-type nebulizer.     

脉冲MIG焊熔滴过渡最佳方式的控制

基于一个脉冲过渡一个熔滴且熔滴体积不变的思想,提出了在峰值电流和基值电流不变的条件下采用送丝速度预置和峰值弧压调节峰值时间与基值时间的控制方式。试验结果表明:采用这种控制方式,能够在不同送丝速度或不同干伸长下实现一个脉冲过渡一个熔滴且熔滴体积基本不变。     

气溶胶粒子对光场增强的研究

本用几何光学方法对光束通过透明气溶胶粒子时，产生的光场增强现象进行了分析。导出了气溶胶粒子前向临界区域光能密度有较大增强，而在光轴上相对较小。并对液态气溶胶粒子做了实验，用波长γ＝０．４８８ｕｍ的激光束照射气溶胶粒子，在实验中观察到了光场增强点，可以预言：光学击穿等非线性效应，将言先从增强点发生。     

HAN基液体发射药液滴燃烧的简化模型

针对ＨＡＮ基液体发射药的ＬＰ１８４６液滴的燃烧特点，建立相应的分区简化模型。在一些简化假设的基础上，找到了液滴质量燃速的近似解析解。理论计算值和实验数据吻合较好。