Bubble formation of liquid boiling in microchannels

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液态LPG在闪急沸腾下的喷雾可视化研究

文章设计了高压LPG喷雾实验装置,使用高速CCD相机和光学纹影法分别拍摄了不同喷油压力下,直喷发动机用相同喷孔径旋流喷嘴和非旋流喷嘴的液态LPG自由喷雾过程.结果表明:随喷射压力的增加,液态LPG喷雾的贯穿距离增大,而喷雾锥角减小;液态LPG在喷出后会产生闪急沸腾现象,导致LPG的喷雾贯穿距离比汽油喷雾的贯穿距离小一些,而喷雾锥角则大于汽油喷雾锥角;相对于非旋流喷嘴来说,旋流喷嘴燃油雾化效果更好,加速了喷雾的蒸发,有利于混合气的形成.     

Perspective on liquid metal enabled space science and technology

With the rapid development of deep space exploration and commercial flight, a series of tough scientific and technological challenges were raised, which urgently require ever advanced technologies to tackle with. Recently, liquid metals, as a kind of newly emerging functional material, are attracting various attention and many breakthroughs have been made on earth. Such a scientific trend also suggests promising approaches for solving those extreme challenges in space environment. To fulfill the increasing needs thus involved, this article is dedicated to systematically introducing liquid metal material and its related disciplines into space science and technology. Firstly, existing application of liquid metal cooling for space nuclear power was summarized. Then, some potential space practices were tentatively put forward, such as liquid metal thermal interface medium,liquid metal phase change material, liquid metal convection cooling, metal alloy thermal storage, liquid metal electromagnetic shielding and liquid metal electronic printing. Fundamental as well as practical issues that would differ with earth were interpreted. Finally, potential liquid metal space experiments were proposed to investigate the liquid metal hydrodynamic characteristic, wettability and phase change mechanism in space physical environment. Overall, liquid metal enabled space science and technology investigation will not only help efficiently solve the current and future space technological problems, but also aid to stimulate the advancement of liquid metal space material science.     

液态金属磁流体发电机空载电压

为了探究影响液态金属磁流体发电机空载电压的因素,建立发电通道三维流动模型. 采用计算流体力学（CFD）技术,研究发电通道入口速度、磁感应强度、通道宽度、通道高度、液态金属类别对空载电压的影响. 考虑哈特曼层电流回流现象,通过添加绝缘块,对发电通道装置进行结构改进. 从改进后的磁流体速度分布和电流密度变化两方面,分析空载电压优化机理. 结果表明：空载电压与入口速度、磁感应强度、通道宽度成正比,与通道高度无明显关系,但是通道宽度越大,空载电压相对误差越高;高密度、低电导率的液态金属会降低空载电压. 发电通道改进前,空载电压的相对误差为12.3%;改进后的发电通道,空载电压比改进前提高13.3%,相对误差降至0.6%.     

铁液电化学定硫传感器热力学分析

综合分析了金属液电化学定硫传感器在热力学上的可行性。结果表明，以氧化钇稳定氧化锆为固体电解质，硫氧化钇为辅助电极的定硫传感器在铁液硫含量的范围内性能稳定，精确度高，误差小。从理论上讲，该传感器完全可以适用于测定金属液中的硫含量。     

金属液固体电解质定硫传感器研究

在热力学分析的基础上，开发了以氧化钇稳定氧化锆作固体电解质，Y2O2S与Y2O3混合粉末为辅助电极的金属液定硫传感器．电池构造形式为：Ni—Cr｜Cr-Cr2O3｜ZrO2(Y2O3)｜Y2O3 Y2O3S｜[S]Fe｜Ni—Cr．采用整体成型技术组装定硫传感器半电池，分别在实验室和工业现场对传感器的性能进行了测试，结果表明，该传感器具有良好的化学稳定性和快速响应性．     

一类新离散孤子方程的达布变换与精确解

基于一个新的离散等谱问题 ,利用规范变换与Darboux矩阵方法 ,为一族新的离散孤子方程建立了一个达布变换。作为应用 ,获得了离散孤子方程的精确解 ,并借助Mathematica画出了该解的图形     

Thermal evaluation of the injectable liquid metal bone cement in orthopedic treatment

The thermophysical properties of bone cement are important parameters for its application in the orthopedic treatment. This article focused on the thermal evaluation of the low-melting-point metal(Bi In Sn alloy), which has been proved to be an excellent bone cement. Firstly, the basic thermophysical properties of Bi In Sn alloys with different melting points were measured.Secondly, 15 fresh porcine femurs placed in the saline bath, bone cements with different melting points and amounts were injected into the bone cavities, respectively. Thermocouples were used to measure the temperature changes of the bone-cement interface and peripheral bone tissue. The possibility of thermal necrosis was evaluated. Moreover, a three-dimensional human knee model was built to numerically assess the effects of thermal parameters, such as melting point and latent heat on tissue temperature distribution. All the experimental and numerical results implied the heat distribution in the tissue depended on the thermal performances of liquid metal bone cement(LMBC). For LMBC of the same melting point, with increased amounts, the damage to the bone tissue is more severe, while for the same amount of different melting point LMBCs, with the higher melting point, which will lead to more serious damage to the tissue. Also, higher latent heat of LMBC has distinct longer solidification process, which may cause irreversible damage to surrounding tissues. Therefore, in the future, for different clinical surgery needs, the appropriate liquid metal bone cement can be obtained by adjusting the thermal parameters.     

Alternating electric field actuated oscillating behavior of liquid metal and its application

As a class of newly emerging functional material, Gallium based liquid metals have attracted increasing attentions in many fields, such as chip cooling, printed electronics and microfluidics, etc. Particularly, the motion control of liquid metal droplet has been recently tried for its importance in microelectromechanical system (MEMS), microfluidics and potential use in micro-machine or reconfigurable soft robot. This paper is dedicated to explore the motion behavior of liquid metal droplet under AC electric field. The quickly induced oscillation phenomena of liquid metal droplet and surrounding electrolyte solution were observed and the major factors to influence such behaviors are theoretically interpreted and experimentally investigated, including the size of the liquid metal droplet, electrode voltage, electrolyte solution concentration and AC signal frequency etc. Moreover, some typical features to distinguish AC filed actuation with DC field are observed, such as intensive fluid waving induced by the resonance stimulation, and the efficient inhibition of solution electrolysis. Finally, two important applications of adopting AC induced surface oscillation of liquid metal droplet to develop solution mixer as well as fluidic pump were demonstrated which successfully avoid gas generation inside electrolyte environment. The bulk oscillation effects of liquid metal as clarified here could be very useful in a variety of areas such as solution disturbance and mixing, and fluid oscillator or pump etc.     

新型液态金属磁流体发电动力学特性数值模拟

为获得新型液态金属磁流体发电机的流动规律,对空载发电通道动力学特性进行三维数值模拟研究。采用基于Fluent软件的感应磁场法和修正的K-ε湍流模型保证计算精度;对比分析近壁面和中心层的速度及电磁力分布;定义速度波动程度,选取不同物理参数,对发电有效段下游的速度剖面及其波动程度量化分析。结果表明,发电有效段下游速度波动程度最大,速度剖面及其波动程度受发电通道参数的影响明显。当通道宽度相同时,相互作用参数决定速度剖面波动程度,相互作用参数与速度波动程度成正比;随着宽度增大,相互作用参数对速度波动程度影响下降。     

三元金属熔体活度系数计算的模型研究

利用自由体积理论和新一代几何模型,建立了三元金属熔体括度系数lnγ0i的模型表达式,计算出1873K温度条件下铁基熔体中组元的活度系数,并将模型计算结果与文献精选数据进行比较,表明活度系数的模型计算结果与文献精选数据相当吻合.     

液态CO_2相变致裂二次增透技术

针对平煤十三矿瓦斯压力高、含量高,前期水力冲孔效果不理想,钻孔后期抽采效率低等情况,将液态CO_2相变致裂技术应用于煤层二次增透。采用理论分析与现场试验相结合,阐述相变致裂机理,分析液态CO_2相变致裂技术优势,考察相变致裂效果。现场试验表明,相变致裂后,煤层裂隙大幅增加,抽采54 d,煤层瓦斯单孔平均抽采纯量为致裂前的1.08~1.73倍。     

形变Boussinesq方程的N-波达布变换和（2N-1）-孤子解

借助符号计算构造出形变Boussinesq方程的Lax对,构建了一个包含多参数的N-波达布变换,应用达布变换,得到形变Boussinesq方程新的（2N-1）-孤子解,通过图像研究孤子解的性质,这些解和图像对理解水波的传播现象可能有所帮助。     

MICP修复重金属污染溶液及矿化垃圾土试验研究

大量非正规垃圾填埋场面临超负荷运营困境,衍生出系列亟待解决的环境问题。重金属含量较高的垃圾渗滤液易对填埋场周边水体造成污染,填埋场开采扩容产生的矿化垃圾土也存在Cd、Pb、Zn和Cr(Ⅲ)等重金属超标现象,在资源化利用过程中容易造成二次污染,因此,垃圾填埋场重金属污染问题亟待解决。近年来,微生物诱导碳酸钙沉淀技术（MICP）固定重金属的能力被广泛探究,其中巴氏芽孢杆菌因环境适应性强、脲酶表达量高而备受关注。但相关研究中的修复对象主要为污染溶液和普通污染土壤,其与垃圾渗滤液以及矿化垃圾土在污染成因和化学成分等方面明显不同。鉴于此,开展巴氏芽孢杆菌修复重金属污染溶液和污染矿化垃圾土试验,探究巴氏芽孢杆菌生物修复重金属的可行性,分析生物修复前后矿化垃圾土中重金属形态变化以及修复机理。结果显示,巴氏芽孢杆菌对溶液中Cd、Pb、Zn和Cr(Ⅲ)修复率可分别达到95%、84%、5%和98%,对矿化垃圾土中可交换态Cd、Pb和Zn修复率亦可分别达到74%、84%和62%,可交换态Cr(Ⅲ)修复处理前含量几乎为0;经生物修复,矿化垃圾土中可交换态和碳酸盐结合态重金属含量降低,铁锰氧化物结合态和残渣态重金属含量增加;同时,矿化垃圾土中含Fe和Al成分以及MICP过程产生的碳酸钙沉淀共同促进重金属向更稳定形态转化。     

一种离子液体作为Q215钢表面前处理剂的抗腐蚀性能

以月桂酸、三乙烯四胺、氯化苄和四氟硼酸为原料,合成了一种水溶性咪唑啉离子液体,用红外光谱法对中间体咪唑啉及离子液体进行结构表征;以该离子液体水溶液作为金属表面转化膜处理剂,通过浸渍法对Q215钢片表面进行处理后作为工作电极,用塔菲尔方法测试了不同浓度、pH的处理液对碳钢自腐蚀电位和腐蚀电流密度的影响,结果表明,处理液质量浓度2.0g/L、pH 5.5条件下电极自腐蚀电位和腐蚀电流密度均小于其他处理条件;用交流阻抗法研究了不同浸泡时间对碳钢表面防腐蚀膜层极化电阻的影响,结果显示室温2.0g/L、pH 5.5离子液体的处理剂在浸泡工作电极45~60min后所形成的防腐蚀保护膜极化电阻较大,45min以后浸泡时间的增加引起的极化电阻增大程度不明显,离子液体在钢表面形成腐蚀保护膜已达稳定状态。     

沿海废灶兴垦时期的商灶之争

叙述了我地区民国初年“废灶兴垦”时期爆发的商灶剧争的经过，剖析了负责兴垦的垦务公司对灶民所有的荡产进行巧取豪夺的史实，证明了“废灶兴垦”的资本主义性质，指出了研究这段历史对建立海盐博物馆有着特殊重要的意义。     

Electrically driven chip cooling device using hybrid coolants of liquid metal and aqueous solution

Heat dissipation of electronic devices keeps as a tough issue for decades. As the most classical coolant in a convective heat transfer process, water has been widely adopted which however inherits with limited thermal conductivity and relies heavily on mechanical pump. As an alternative, the room temperature liquid metal was increasingly emerging as an important coolant to realize much stronger enhanced heat transfer. However, its thermal capacity is somewhat lower than that of water, which may restrict the overall cooling performance. In addition, the high cost by taking too much amount of liquid metal into the device also turns out to be a big concern for practical purpose. Here, through combining the individual merits from both the liquid metal with high conductivity and water with large heat capacity, we proposed and demonstrated a new conceptual cooling device that integrated hybrid coolants, radiator and annular channel together for chip thermal management. Particularly, the electrically induced actuation effect of liquid metal was introduced as the only flow driving strategy, which significantly simplified the whole system design. This enables the liquid metal sphere and its surrounding aqueous solution to be quickly accelerated to a large speed under only a very low electric voltage. Further experiments demonstrated that the cooling device could effectively maintain the temperature of a hotpot (3.15 W/cm²) below 55ºC with an extremely small power consumption rate (0.8 W). Several situations to simulate the practical working of the device were experimentally explored and a theoretical thermal resistance model was established to evaluate its heat transfer performance. The present work suggests an important way to make highly compact chip cooling device, which can be flexibly extended into a wide variety of engineering areas.     

Duality of boiling systems and uncertainty phenomena

Interactions among dry patches at high heat flux are theoretically analyzed. The high heat flux boiling experiments on metal plate wall with different materials and thickness are correspondingly conducted. The duality of boiling system, i.e. hydrodynamic performance and self-organized performance is identified. A unified explanation of hydrodynamic models and dry patches models is given. The scatter and uncertainty in boiling data can be mainly attributed to the intrinsic duality, but not the sole surface effects. The present experimental results explain why the deviation point at high flux boiling is seen only on occasion and why the self-organization of dry patches is often ignored in available literature.     

Ultrasonic transducer array tomography for detecting defect of metal plate based on Hilbert transformation

Hilbert transformation and improved ellipse localization method is applied in ultrasonic transducer array tomography to detect defect of metal plate.By combining the improved ellipse localization metho...     

Flux-measuring approach of high temperature metal liquid based on BP neural networks

A soft-measuring approach is presented to measure the flux of liquid zinc with high temperature and causticity. By constructing mathematical model based on neural networks, weighing the mass of liquid zinc, the flux of liquid zinc is acquired indirectly, the measuring on line and flux control are realized. Simulation results and industrial practice demonstrate that the relative error between the estimated flux value and practical measured flux value is lower than 1.5%, meeting the need of industrial process.