曲轴红套感应加热的数值仿真

为了将感应加热技术应用于曲轴红套工艺中,建议在曲臂孔内侧布置一个圆形线圈的同时,在位于曲臂孔与曲柄销之间的曲臂外围再布置一个矩形线圈,通过建立曲臂感应加热有限元分析模型,利用ANSYS软件对不同线圈参数条件下曲臂在感应加热过程中的温度场分布情况进行了数值仿真研究,结果表明,通过调整感应线圈电流密度、交变频率等工艺参数,可以确保曲臂孔四周温度分布均匀,进而满足曲轴红套工艺质量的要求。此外,还对感应加热的影响因素进行了探讨。     

Design and optimization of coil structure based on the uniformity of core temperature field

Coil structure size parameters during electromagnetic induction heating affect the temperature field and heating rate of a carbon fiber-reinforced polymer (CFRP) shell. In this study, a finite element analysis model is established on the basis of a single-screw coil structure, and the influence of coil diameter, length, turns, and position relationship on the temperature field distribution and heating rate of the CFRP shell is studied. According to image entropy theory, the influence of coil structure size parameters on the uniformity of a temperature field distribution is analyzed. Furthermore, the accuracy of the coil structure size parameters with respect to temperature field variation is verified with a CFRP induction heating experiment. This study provides theoretical support and a verification method for the selection, design, and optimization of the coil structure size parameters of CFRP shells during induction heating.

     

电磁感应加热系统的近似变压器模型

针对电磁感应加热中某一温度分布的控制电压难以计算的问题,建立了加热系统的近似变压器模型.首先,把加热线圈和加热物体分别等效成3个电感线圈,作为变压器的一次侧和二次侧绕组；其次,求出各线圈电阻电感参数和二次侧电流,然后由各绕组互感关系推导出的二次侧电流和一次侧电压关系式,估算出控制电压；最后,利用ANSYS软件仿真出控制...     

Improvement of the Uniformity of the RF Field Generated by the Helical Surface Coil of a Nuclear-Quadrupole-Resonance Spectrometer

A simple and rather efficient method is proposed for improving the uniformity of the RF field generated by a surface helical coil with nonlinearly distributed turns. An optimal law of the distribution of the turns of a helical coil is suggested. The results of a computer simulation of the field produced by this coil are presented and compared with the data for a conventionally used coil in the form of a linear spiral. The coils were tested during detection of nuclear quadrupole resonance signals on ¹⁴N nuclei in a (CH₂)₆N₄polycrystal and demonstrated the efficiency of the technique proposed for improving the field uniformity.     

一种任意正交折线线圈阻抗的解析建模新方法

提出了一种位于导体上方正交折线线圈的阻抗解析建模方法。首先,在前人研究的基础上,定义了外形位置因子,得出了单矩形线圈的入射场感应电压及散射场电压简化计算方法;其次,将多个矩形线圈自感电压及两两之间的互感电压叠加,建立了串联等效电感模型;再次,根据任意正交折线线圈的几何原理,将该线圈拆解为有限个相同截面的矩形线圈并进行重构,得出入射场阻抗及散射场阻抗的广义二重积分表达式。最后,利用Mathematica对回折线圈实例进行了计算与实验比较,并根据影响阻抗的各个变量绘制阻抗平面图。拆解重构方法可用于不同形状、不同激励频率、不同提离高度的正交折线线圈平行置于任意电导率导体上方的阻抗解析计算。     

热泵热水器蓄热水箱的数值模拟与结构优化

利用ANSYS数值模拟软件中的ICEM和FLUENT模块对静态加热式热泵热水器蓄热水箱内温度场和速度场进行了模拟计算,研究分析了不同的盘管直径及位置对水箱内部速度场与温度场的变化的影响,在此基础上提出了一个有关于冷凝盘管结构改进的优化方案。     

涡流热成像裂纹检测中的形状大小影响分析

涡流热成像无损检测技术可以对金属表面裂纹进行快速、准确的检测,但是不同的线圈、试件以及裂纹大小对检测效果影响很大。通过建立感应加热二维模型,选取裂纹处与非缺陷处温差作为特征量,对不同组成部分形状大小对涡流热成像检测的影响规律进行了数值模拟;对比分析了不同裂纹深度下温差随体积深度比的变化规律,采用数据拟合方法研究了相似裂纹检测规律,并提取出试件形状以及线圈形状对检测效果的影响曲线;最后进行了涡流热成像试验验证。结果表明:当裂纹深度较大时,体积深度比影响规律可分为上升阶段、平稳阶段和下降阶段;相似裂纹间温差变化符合二次变化规律;涡流热成像技术可有效检测超大或超厚试件表面裂纹;减小线圈提离、曲率和线径的大小有助于增强检测效果。实际检测过程中,可据此针对不同被检试件采用不同线圈,提高检测能力。     

一种小型磁谐振式无线电能传输系统的实验研究

针对基于电磁感应的无线充电的Qi标准实现充电的前提是两线圈必须相靠极近且位置相对固定的问题,对磁谐振式无线电能传输技术的原理及模型进行了研究,并分析了几个影响电能传输效率的因素。设计并制作了一种小型磁谐振式无线电能传输系统的发射端线圈,以增加无线电能传输的距离及产生较大范围的磁场,从而使接收端可以在更大范围内移动,接收端线圈则采用了通用的接收线圈以增加系统的实用性。实验结果表明,该系统能正常工作并且发现系统的谐振点,同时发现在该工作状态下传输的电能也最多,同时传输距离也变长。     

磁致伸缩微小驱动器驱动电磁线圈的设计研究

激励磁场强度对磁致伸缩驱动器驱动位移的大小具有决定作用。对于微小磁致伸缩驱动器 ,如何进行驱动线圈的整体设计 ,使小尺寸线圈产生较大磁场强度是本研究的主要目标。通过优选电磁线圈参数Gcoil确定线圈几何结构尺寸 ,并通过建立磁场强度Hcoil与电磁线圈的电流密度Jcoil进而与电磁线圈线径 之间的关系模型计算和优选电磁线圈线径来提高线圈电磁转化率 ,从而增大激励磁场强度是研究的具体方法。针对 7mm× 2 0mm的Terfenol D试样确定驱动线圈几何参数Gcoil=0 .17,线圈电流密度为最大时的线径 =1mm。 1mm线径的电磁线圈 ,经ANSYS计算 ,比线径为 0 .5mm线圈产生的磁化强度提高了 2 5 %     

内混式喷嘴雾化特性的试验与仿真研究

利用马尔文测雾仪对内混式喷嘴在不同工况下的雾化特性进行试验研究。根据试验结果,分析气压、水压以及气液比等因素对液滴粒径及均匀性的影响。利用Fluent软件对内混式喷嘴进行数值模拟,研究喷嘴混合段以及外流场的粒径变化。结果表明:随着气压、气液比的增加,喷嘴的雾化粒径减小,且气压为主要影响因素;内混式喷嘴内部粒径先增大后减小,在喷嘴出口处锐减,外流场中粒径沿轴向方向逐渐增大;将喷嘴出口处模拟粒径与实验结果对比,粒径大小及其变化趋势吻合较好。     

Analysis of the induction heating for moving inductor coil

Induction heating is a process that is accompanied with magnetic and thermal situation. This paper presents a simulation of a magneto-thermal coupled problem of an induction heating process for moving inductor coil. In the magnetic and thermal analyses, temperature-dependent magnetic and thermal material properties were considered. As the inductor coil moves in the process, solution domains corresponding to inductor changes into those of the air, and the solution domains of air change into those of the inductor. For these reasons, modeling of induction heating process is very difficult with general purpose commercial programs. In this paper, induction heating process for moving coil was simulated with the concept of traveling the position of the heating planes. Finite element program was developed and finite element results were compared with the experimental results.     

平板件电磁成形用线圈的设计

通过对线圈产生的磁感应强度的推导，并结合实验结果分析，得出线圈形状选择时遵循的原则：长形工件采用椭圆形线圈要优于圆形线圈，中心部位变形要求较高的工件应尽可能采用圆形线圈。通过对平板件上电磁力分布特点的分析，确定在成形特定尺寸的工件时，存在一个最小线圈尺寸，若线圈最外圈尺寸小于该尺寸，则工件边缘部分所受磁场力垂直向上，不利于工件的变形。从设备能量利用率的角度进行分析，得出在设备能量相同的情况下，板料厚度等于趋肤深度时，设备能量利用率最高，板料变形程度最大。在设备电容确定的情况下，可以通过改变线圈导线的材料、规格、线圈的匝数、匝间距等获得最高的设备能量利用率．     

A novel nanofluid manufacturing process using a cylindrical flow cooling method in an induction heating system

The main purpose of this study is to develop a cylindrical flow cooling method in an induction heating system that is capable of producing the nanofluid. The system consists of a high frequency induction heating system, vacuum system, temperature control system, and a cylindrical curtain collector. The raw material Zn is evaporated by the high frequency induction heating system. The gas phase Zn is condensed and collected by a water cylindrical curtain collector. During the process, the gas phase Zn is oxidized. The ZnO nanoparticles were collected and suspended in de-ionized water. Through transmission electron microscopy (TEM), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and particle size analyzer (PSA), a set of applicable parameters size can be obtained. Results show that the lower the collecting liquid temperature and the shorter the collecting distance, the smaller the nanoparticle size obtained. An aspect of UV/V is absorbency, the produced ZnO nanofluid absorbed UV when the wavelength is 360 nm to 380 nm.     

COMPUTER SIMULATION OF CONTINUOUS ELECTROMAGNETIC STIRRING FOR MAKING RHEOLOGIC SEMI-SOLID SLURRY OF ZL112Y ALUMINUM ALLOY

To realize the technology of fabricating the rheologic semi-solid slurry of ZL112Y aluminum alloy via continues electromagnetic stirring process, ANSYS software was used to simulate electromagnetic force field and fluid velocity field in the alloy melt in a crucible tube in three coils. In the first section of the paper, eletromagnetic force field and fluid velocity field caused by single coil were simulated. The result of this simulation gives an average velocity of 3.2 cm/s and it is called critical velocity because a fluid velocity over it will cause a fine and spherical structure of solid primary a in a semi-solid melt. And, from this result, a reasonable temperature of semi-solid of the alloy and an electrical current intensity were established. The electrical current intensity of the result of this simulation corresponded to the current intensity used in a practice experiment, in which the primary α was obviously refined and sphericized. Based on this simulation of single coil electromagnetic stirring, in the second section of the paper, eletromagnetic force field and fluid velocity field caused by three coils were simulated. The result of the simulation shows that, 1） there is a semi-solid zone of 32 mm from bottom of the crucible tube to the upper; 2） the electrical current intensities of three coils of 400 A, 600 A, and 400 A, which were set to top range, middle range and bottom range of the tube, respectively, were the optimum parameters of electromagnetic current intensity under the condition of this investigation; and 3） under effect of these electromagnetic current intensity, the fluid velocities of the melt in the tube were 6.3 cm/s in top range, 3.75 cm/s in middle range, and 3.9 cm/s in bottom range of it, respectively.     

电感式磨粒传感器中铁磁质磨粒特性仿真研究

针对机械装置的在线监测传感器,模拟了铁磁质磨粒通过传感器过程中传感器线圈的磁场和感应线圈的感应电压瞬态变化特性.考虑了线圈与铁磨粒的材料、线圈匝数和激励线圈的输入电压等因素,应用Jmag Designer I0.4软件建立了传感器的二维有限元模型.仿真结果揭示了磨粒运动过程中线圈磁场与感应线圈中感应电压的变化规律,获得了感应电压与球形磨粒的直径大小的立方成正比,与磨粒运行速度成正比.研究结果对于电感式磨粒传感器的开发具有重要的指导价值.     

互补式双层时栅角位移传感器研究

针对当前研制的双层时栅角位移传感器感应信号幅值小、时变磁场的均匀有效面积利用率低等问题,在原有“八”字形半正弦结构的基础上提出了一种双层互补式时栅角位移传感器设计方案。根据双层时栅位移传感器的特点,建立了其空间磁场分布模型,验证了双层时栅角位移传感器的互补式结构在构成行波上的优势;根据激励线圈的磁场分布规律进行建模,得到该参数状态下双层平面激励线圈的间距为0.235 mm。最后进行了有限元仿真分析和实验验证。仿真分析表明：采用互补式结构能有效增大感应信号强度,传感器的短周期误差峰峰值显著降低,能够有效抑制角度误差中的1次谐波和4次谐波。实验数据表明：传感器短周期原始误差为(-13.61″,13.30″),修正后误差为(-3.01″,0.78″);传感器长周期原始误差为(-19.60″,21.96″),修正后误差为(-2.62″,3.30″);相比单层“U”字形结构,1次误差减小了66.3%,4次误差减小了25.3%。     

基于平面线圈的高分辨力时栅角位移传感器

针对现有时栅角位移传感器采用漆包线绕制工艺加工线圈,导致线圈布线不均且容易随时间发生变化进而影响测量精度的问题,提出一种基于PCB技术的新型时栅角位移传感器。该传感器通过在PCB基板的不同层上布置特定形状的激励线圈和感应线圈,形成两个完全相同并沿圆周空间正交的传感单元;当在两传感单元的激励线圈中分别通入时间正交的两相激励电流后,通过导磁定子基体和具有特定齿、槽结构的导磁转子对传感单元内的磁场实施精确约束,使两传感单元的感应线圈串联输出初相角随转子转角变化的正弦感应信号;最后通过高频时钟脉冲插补初相角实现精密角位移测量。利用有限元分析软件对传感器进行了建模和仿真。根据仿真模型制作了传感器实物,开展了验证实验,并对实验中角位移测量误差的频次和来源进行了详细分析。经过标定和补偿,最终获得了整周范围内误差在-2.82″~2.02″的时栅角位移传感器。理论推导、仿真分析和实验验证均表明,该传感器不仅能实现精密角位移测量,还能在激励线圈和感应线圈空间极距和信号质量不变的情况下,将位移测量的分辨力从信号源头提高1倍,且结构简单稳定、极易实现,特别适用于环境恶劣的工业现场。     

Integrated numerical analysis to evaluate replication characteristics of micro channels in a locally heated mold by selective induction

High-frequency induction heating is an efficient way to heat mold surfaces by electromagnetic induction using a non-contact procedure. Due to its ability to rapidly heat and cool mold surfaces, this method has been applied recently to the injection molding of micro/nano structures. The present study investigates a localized heating method involving the selective use of mold materials to enhance the heating efficiency of high-frequency induction heating. A composite injection mold consisting of ferromagnetic material and paramagnetic material was used for localized induction heating. The feasibility of this localized heating method was investigated through numerical analyses in terms of its heating efficiency for localized mold surfaces and the resulting flow characteristics in micro channels. To take into account the effects of thermal boundary conditions of localized induction heating, a fully integrated numerical analysis effectively connecting electromagnetic field calculation, heat transfer analysis, and injection molding simulation was carried out. The proposed integrated simulation was applied to the injection molding of a rectangular strip containing micro channels, and the resulting mold heating capacity and replication characteristics of the micro channels were compared with experimental findings in order to verify the validity of the proposed simulation.     

多参数协同调制的高分辨力直线时栅位移传感器

为了解决高精度的直线时栅位移传感器依赖空间超精密刻线和刻线不均匀等问题,提出一种采用多参数协同调制的新型直线时栅位移传感器。该传感器通过在PCB基板上布置阵列的激励线圈和特定形状的感应线圈,通过调制感应的面积和线圈的参数,感应出电行波信号,经过整形后用高频时钟脉冲插补得到位移量。通过仿真分析设计与样机实验,得出实验结果表明,在不改变空间极距的情况下,使得分辨力在信号源头上提高1倍且有±68μm的测量精度。     

微机械电磁阻尼结构分析

提出采用电磁阻尼结构来提高微机械角度调节装置的响应速度.通过建立结构模型和分析结构参数对阻尼效果的影响,给出具体设计实例以及制作工艺,证实该阻尼结构的有效性和可行性.