磁控电导流体传热的振荡强化

研究了圆管形通道中电导流体在磁场和声场作用下的传热性质,导出了等效增强热扩散率与振荡频率和Harttmann数Ha的解析关系.结果表明,外加磁场和振荡都能够使电导流体的传热得到强化.     

磁流体振荡传热实验研究

研究了水平管道中磁控磁流体的振荡传热增强，获得了通过声场和磁场都能控制磁流体传热的结果。实验显示，适当的频率出现纵向传热最大，适当的磁场大小出现纵向传热最大，过大或过小的频率和磁场传热增强并不理想。     

磁流体振荡传热实验研究

研究了水平管道中磁控磁流体的振荡传热增强,获得了通过声场和磁场都能控制磁流体传热的结果.实验显示,适当的频率出现纵向传热最大,适当的磁场大小出现纵向传热最大,过大或过小的频率和磁场传热增强并不理想.     

磁性流体在不互溶液体中流动及传热研究

本文分别从实验和理论角度研究了由水基磁性流体和煤油组成的不互溶物系中，单个分散相液滴在连续相中的流动及传热规律。通过对传热实验数据的整理，关联出一新的经验关系式，并将其与理论分析数值计算的结果进行了比较，两者的误差较小。本文还研究了磁场对流动和传热的影响，随着场强的增加，液滴下落的均速度增加，传热系数提高。     

振荡热管的研究现状与应用前景

振荡热管作为一种新型独特高效的传热元件,具有体积小、结构简单、传热良好、适应性广等优点.在电子元件散热、新能源利用及余热回收等领域都极具潜力.本文综述了振荡热管的结构、工作原理、运行机制;概括了国内外研究现状;列举了振荡热管在几个领域的工程应用及应用前景;在前人的基础上总结出振荡热管目前存在的问题,以及解决方法,指出振荡热管的多样化、微型化、实用化是今后的研究方向。     

热管式CPU散热器总传热能力的研究

本文对一种热管式CPU散热器的传热机理、传热路线和各传热阶段的热阻进行了定性分析和定量分析，建立了该热管式散热器传热模型，导出了其总传热系统的计算式，并给出了计算实例。     

EHD强化传热机理分析

通过综合国际上电水动力学ＥＨＤ强化传热的最新研究成果，分析了在电场力作用下流体所受到的各种力及其对单相对流传热，沸腾传热和凝结传热的影响，给出ＥＨＤ强化传热的基本方程，并对几个重要的影响因素进行了讨论，指出了ＥＨＤ强化传热的复杂性和研究方向１。     

空冷单元风机出口导流板优化的数值模拟

空冷单元结构的优化对于提高空冷凝汽器的换热效果有着重要意义。针对600 MW直接空冷凝汽单元的典型结构,建立了在风机出口安装弓形导流板的空冷单元物理模型。为了对被安装导流板的倾角和宽度进行优化,利用FLUENT软件对加装不同倾角和不同宽度导流板的空冷单元内部流场分别进行了数值模拟,分析了导流板不同倾角和宽度对内部空气流动和传热特性的影响,得到了在该单元中加装弓形导流板的最佳倾斜角度和最佳宽度,为空冷单元结构的优化设计提供一定的参考依据。     

板式脉动热管的磁流体实验研究

脉动热管被认为是超高热流密度功耗的工况中最具前景的散热元器件之一,与逐渐发展成熟的纳米技术一同被广泛应用于电子散热设备中,因此探究纳米流体脉动热管的运行与热特性变化机理十分重要。通过采用外加磁场的方法来强化纳米磁流体脉动热管传热的实验研究,搭建了纳米磁流体脉动热管的传热测试可视化实验台。分别测量了在磁场为25、5、1、0 m T以及在2种不同磁场方向(脉动热管蒸发段的正后方与正下方)作用下,板式脉动热管的温度分布和传热速率,研究了纳米磁流体、热负载功耗、磁感应强度与磁铁摆放位置等因素对其换热性能的影响。实验结果表明,用四氧化三铁/乙醇纳米流体作为工作流体,在磁场作用下可以显著强化脉动热管的传热性能,其中置于脉动热管蒸发段正下方的永磁体能够更多地优化脉动热管的传热性能,这可为超高热流密度功耗的工况提供借鉴指导。     

高炉炉墙三维传热的计算与分析

应用有限单元法分析了高炉炉墙的三维传热问题，探讨了简洁，实用的三维传热有限元求解方法，得到了近乎实际的计算结果。     

Particle image velocimetry for an automatic cooling device using temperature-sensitive magnetic fluid

An automatic cooling device has been developed by using a temperature-sensitive magnetic fluid as the coolant. A particle image velocimetry (PIV) system was used to measure the flow velocity of the fluid inside the loop. The efficiency of the device under varying conditions such as the heat load and the power of cooling were experimentally investigated. The effect of cooperation between external magnetic field and thermal field on the performance of the device was studied. As expected, a continuous flow induced by the thermal and magnetic field was observed in the loop, where heat was transferred by the circulating magnetic fluid. The synergic effect between the magnetic field and the temperature gradient has impact on the performance of the device.     

磁流体力学及磁流体的工程应用

简要介绍磁流体的一般性质、研究方法及研究现状．讨论磁流体的粘度、导热系数等物理特性及其在磁场作用下的变化规律．综述了磁流体力学的研究方法及磁流体流动时的控制方程组．给出磁流体在磁场方向与管轴一致的直管内流动时的流动方程．并举例介绍了磁流体在电子、机械、冶金、化工、动力、医疗等方面的应用开发及应用前景，指出磁流体在这些领域内应用有其他物质无法相比的优越性．     

磁场作用下倾斜方腔内纳米流体自然对流数值模拟

采用Chebyshev配置点谱方法对倾斜方腔内纳米流体自然对流换热进行了数值模拟.倾斜方腔的左右壁面为恒温壁面,上下壁面为绝热壁面,并施加了与方腔下壁面平行的磁场.方腔内充满了以水为基液的不同纳米颗粒.研究方腔倾斜角度γ、Gr数和纳米颗粒对纳米流体流动与传热的影响.研究结果表明:传热在倾斜角度为π/4时最大,当方腔倾斜...     

Peristaltic transport of MHD Williamson fluid in an inclined asymmetric channel through porous medium with heat transfer

The intention of this investigation is to study the effects of heat transfer and inclined magnetic field on the peristaltic flow of Williamson fluid in an asymmetric channel through porous medium. The governing two-dimensional equations are simplified under the assumption of long wavelength approximation. The simplified equations are solved for the stream function, temperature, and axial pressure gradient by using a regular perturbation method. The expression for pressure rise is computed numerically. The profiles of velocity, pressure gradient, temperature, heat transfer coefficient and stream function are sketched and interpreted for various embedded parameters and also the behavior of stream function for various wave forms is discussed through graphs. It is observed that the peristaltic velocity increases from porous medium to non-porous medium, the magnetic effects have increasing effect on the temperature, and the size of the trapped bolus decreases with the increasing of magnetic effects while the trend is reversed with the increasing of Darcy number. Moreover, limiting solutions of our problem are in close agreement with the corresponding results of the Newtonian fluid model.     

磁性流体行波泵实验装置的研究

磁性流体行波泵作为磁性流体的典型应用已经得到了普遍的关注。行波磁场的产生、泵体结构的设计、磁性流体的动力学特性等均为磁性流体行波泵研究的关键技术。根据行波磁场产生的形式设计了旋转型磁性流体行波泵。行波磁场作用下的磁性流体流量与产生行波磁场的永磁转子的磁极旋转的角度有直接关系,永磁转子磁极旋转过的角度越大,其流量也越多;行波磁场的强弱对磁性流体流量也会产生影响,当永磁转子磁极旋转相同角度时,磁场越强,其流量越大;在永磁转子旋转相同角度时,行波磁场的频率只能影响磁性流体的流速,对流量不直接产生影响。     

基于FLUENT的管壳式换热器壳程流场数值模拟研究

利用ANSYS参数化建模方法建立了管壳式换热器的参数化模型,在ANSYSFLUENT中对管壳式换热器壳程流体的流动与传热进行了数值模拟计算,得到换热器壳程流体温度场、速度场和压力场;分析了折流板间距及弦高对换热效率和壳程流体压降的影响,对于设计传热效率高、流体阻力小的换热器进行了有益探索。     

Simulation and control scheme of microstructure in magnetic fluids

By accounting for the external and internal force acting on the suspended magnetic nanoparticles and motion characteristics of the suspended magnetic nanoparticles in the magnetic fluids,the three-dimensional microstructure of magnetic fluids is investigated by means of the molecular dynamics simulation method. The distribu-tion of suspended magnetic nanoparticles and microstructure of the magnetic fluid are simulated in both absence and presence of an external magnetic field. The ef-fects of the nanoparticles volume fraction,the dipole-dipole interaction potential and the particle-field interaction potential on the microstructures of the magnetic fluids are discussed. The main results obtained here are summarized as follows. The suspended magnetic nanoparticles tend to aggregate and make the irregular distribution structure in the absence of an external magnetic field. When the mag-netic fluid is exposed to a magnetic field,the magnetic nanoparticles suspended in the carrier fluid tend to remain chained-alignment in the direction of the external magnetic field. The tendency of chain-alignment morphology of the suspended magnetic nanoparticles is enhanced with the nanoparticles volume fraction,the dipole-dipole interaction potential and the particle-field interaction potential.     

交变磁场下盘型磁流变流体阻尼器的动力特性

为了掌握交变磁场对基于剪切方式的盘型磁流变（MR）流体阻尼器动力特性的影响，试验研究了正弦磁场下支承在盘型磁流变流体阻尼器上的柔性转子系统的动力特性.通过测量不同磁场频率和强度下转子系统的运动轨道、振动时间历程和不平衡响应曲线，并与恒定磁场下的结果进行了比较.结果发现，磁场的频率对盘型磁流变流体阻尼器的动力特性有着显著的影响.随着磁场频率的增大，盘型磁流变流体阻尼器抑制转子振动的能力减小.当磁场的频率高于一个临界频率后，转子系统的动力特性与无磁场时的动力特性相同，正弦磁场不能够控制磁流变流体阻尼器的动力特性.磁场强度越大，正弦磁场的临界频率越高.     

Numerical Analysis of Magnetic Fluid Sealing Performance

1 Introduction There are many factors that can influence magnetic fluid sealing performance[1–4]. The material characteristics of magnetic fluid and the intensity of the magnetic field have a direct influence on the magnetic fluid seal. The main factors that influence the sealing performance include the sealing gap, the shaft eccentricity, the shaft diameter and the cen- trifugal force. Analyzing these factors is important for the design and manufacture of the magnetic fluid. The design and …