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研制的应用于超导磁体系统的电阻应变计,在强磁场下工作,在外磁场的作用下,具有磁阻效应,使之产生视应变。本文着重介绍了不同磁场强度,磁场方向,不同试件材料以及应变计结构对应变计视应变变化的实验研究,从而得到一些规律性的结果。实验研究在磁场从0-8T超导磁体中进行。 相似文献
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基于流体多组分传输的气体绝缘母线温度场数值计算与分析 总被引:1,自引:0,他引:1
气体绝缘母线的工作状态与其散热性能以及温升直接相关。建立了有限元模型计算母线导体焦耳热损耗以及外壳涡流损耗,根据流体力学理论,采用流体多组分传输模型计算母线流场与温度场分布。利用单元映射方法实现涡流场、流场以及温度场的间接耦合,综合考虑母线与其内部绝缘气温度变化特性。针对分相封闭母线及共相封闭母线两种不同母线结构稳态与瞬态温度场进行数值计算,分析了母线与气体及外部空气边界的对流与辐射换热效应、流体物性参数随温度变化特性。针对分相封闭母线及共相封闭母线两种不同母线结构稳态与瞬态温度场进行数值计算,分析了母线与气体交界面对流与辐射换热量的比例关系、传热系数分布以及母线温升随电力负荷与时间的变化过程。通过对比计算结果与传统工程算法、单组分分析方法以及实验结果,验证了该模型的正确性。 相似文献
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气体绝缘母线的散热性能研究是母线设计及状态检测的重要环节。分别建立了分相及三相共箱式母线涡流场、流体场以及温度场有限元分析模型,将涡流场分析得到的焦耳热损耗作为热源间接耦合至流体场与温度场。进行温升计算时,考虑了对流与辐射换热过程中流体密度、导热系数以及动力粘度随温度变化的特性。通过确定换热边界条件,求解出不同结构母线的温度场分布,与实验数据的对比验证了计算结果的正确性。应用此热计算模型研究了环境温度、气体压强以及负荷电流对不同结构母线温度场分布的影响,所得出的结论对于母线设计及其运行期间的状态检测具有一定的参考意义。 相似文献
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基于CPUs/GPUs架构,采用混合热格子-Boltzmann方法,对微重力环境下三维航天器舱简化模型内的混合对流问题进行了详细的非稳态数值模拟。结果表明:具有恒热流边界的元器件位于进风掠过的模型壁面中心时,热壁面平均努塞尔数■最大,换热最强;保持雷诺数Re不变而缩小模型尺寸到1:5及以下时,模型在全重力情况下与原型在无重力时的热壁面■相同,流场和温度场瞬态变化过程几乎一致,可用来指导在地面进行微重力下的实验研究;多GPUs结合格子Boltzmann方法计算的超高效率,可实现航天器电力系统和设备舱内流动换热的实时预测。 相似文献
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研究用于轨道交通的横向磁场电励磁磁通切换磁悬浮直线电机特殊结构下的温升问题,设计冷却系统以保证电机正常运行。分析电机的结构和运行原理,建立了三维稳态温度场数学模型,并推导出边界条件方程。考虑电机各部分热交换的情况,确定各材料的导热系数以及电机不同部分的对流换热系数。通过有限元方法计算出电机的铜损耗与铁损耗,并求出相应的生成热。利用三维有限元法对电机不同工况下的温度场进行计算,得到了电机铁心、电枢、励磁绕组的温度场分布情况。最后,设计冷却系统,比较自然风冷和强制水冷的温度分布,证明该冷却系统装置的可行性和合理性。 相似文献
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A conduction-cooled superconducting magnet with central field of 10T and warm bore of 100 mm was designed based on a Nb3Sn and two NbTi superconducting coils. At the first stage, the NbTi coils have been fabricated and tested. A two-stage 4 K Gifford-McMahon (GM) cryocooler with the second-stage power in 1W, 4.2K is used to cool the magnet from room temperature to 4 K. The superconducting magnet with the same power supply has the operating current of 116A. The magnet can be rotated with a support frame to be operated with either horizontal or vertical position. A pair of Bi-2223 high temperature superconducting current leads was employed to reduce heat leakage into 4.2K level. The NbTi coils reachto the operating current of 120A without training effect to be observed during charging of the magnet during 40 minutes charging time and generate the center field of 6.5T. The training effect in the NbTi magnet directly cool-down by cryocooler and inter-winding support structure in magnet can be remarkably improved. The superconducting magnet has been stably operated for more than 275 hours with 6.5T. In this paper, the detailed design, fabrication, stress analysis and quench protection characteristics are presented. 相似文献
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Teruo Azukizawa 《Electrical Engineering in Japan》1995,115(2):135-143
In a superconductive electrodynamic suspension system, superconducting coils experience a space harmonic magnetic field generated by induced current in the levitation coils installed along the guideway. Current in a superconducting coil varies to keep the total magnetic flux constant when the coil is exposed in an external magnetic field. However, superconducting coil current was treated as constant in the conventional analysis because the electromagnetic forces can be estimated easily. The purpose of this paper is to determine the behavior of the persistent current in making reliable and tough superconducting magnets. A simple method to analyze fluctuating persistent current in a superconducting coil is proposed first. Calculated results for the normal running condition showed that the fluctuations of persistent current are less than 1 percent of the initially excited current for the sidewall levitation system, and less than 2 percent for the ground levitation coil system. Even when the null flux guidance cable is short-circuited, the fluctuation is less than 5 percent. Considering that the magnetic shield effects by the conductive cryostat vessels were neglected in this analysis, the fluctuating magnetic field by levitation coils will never affect the stability for a superconducting magnet. 相似文献
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ⅠIntroductionIt is expected that the middle and small-scale mag-nets immersed in liquid helium will be replaced by theeasy-operating conduction cooled superconducting magnetin near future[1~3].For the aimof superconducting mag-net applications in the advanced material processing,awide bore conduction-cooled superconducting magnet withavailable warmbore of100 mmand center field of 10 Twas designed.The NbTi superconducting coils have beenfabricated and tested.The systemis automated by using… 相似文献
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Akifumi Kawagoe Fumio Sumiyoshi Hidemune Wakamatsu Hidemi Hayashi Satoshi Hanai Takataro Hamajima 《Electrical Engineering in Japan》2005,153(4):12-19
A new type of cable‐in‐conduit conductor composed of HTS tapes was proposed as a winding for high‐performance HTS coils with high current capacities and low AC losses. In the fabrication of the conductor, the twist of stacked tapes around their axes was made before inserting them inside conduits. The twist angle should be changed continuously along the axis to reduce face‐on oriented magnetic fields applied to the tape in the winding conductor during coil operation. In order to confirm the high current capacity of this type conductor, two single‐layered solenoidal coils wound with sample conductors composed of five stacked Bi‐2223 tapes with bias angles of 20 and 0° were fabricated and tested in liquid nitrogen. A copper magnet system was used in this experiment to generate the spread magnetic field with a spread angle of 20° from the coil axis to the radial direction, which simulates the profile of magnetic fields near the edge windings of practical coils. A large improvement on critical‐current degradation affected by spread magnetic fields was successfully observed for the test coil wound with the 20° bias conductor. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 12–19, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20218 相似文献
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对一种强流径向电子束浸没式磁聚焦系统进行了研究和设计。首先介绍了浸没式聚焦径向电子束原理和聚焦系统结构,接着仿真研究了在不同磁场分布下浸没式聚焦400 k V/30 k A径向电子束稳定传输的束轨迹,并根据电子束波动情况优化了径向磁场分布,然后设计了基于永磁体和螺线圈混合结构的径向电子束聚焦系统,最后分析了螺线圈绕制方式对聚焦系统的供电系统的影响。结果表明,径向电子束在设计的聚焦系统磁场下能以小波动稳定传输,并且与单线绕制螺线圈相比,双线绕制螺线圈回路脉冲电流前沿更短,脉冲电流宽度更窄,所需电容更小,更有利于径向电子束聚焦系统的小型化。 相似文献
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高电流密度超导储能磁体的研制 总被引:7,自引:0,他引:7
分析了不同结构超导储能磁体的特点,针对储能量为MJ量级的超导储能磁体计算了漏磁场分布和超导材料的利用率,提出了储能为1 MJ的单螺管型超导储能磁体的设计方案。采用窄液氦通道技术,利用多芯NbTi/Cu复合超导线,研制了储能量为1 MJ的紧凑型超导储能磁体。磁体内径为439 mm,外径为600 mm,高为550 mm。在运行电流为305A时,磁体的最大磁场为4.9 T,中心磁场为4 T。对超导磁体的试验结果表明,磁体的最大运行电流为303 A,放电功率为100 kW。研制的超导储能磁体可作为恒压/恒功率放电的不间断电源的关键部件。 相似文献
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External magnetic disturbance influences the quality of the image obtained with a magnetic resonance imaging (MRI) system because it causes magnetic resonance frequency drift. When a superconducting magnet in persistent current mode operation is exposed to external magnetic disturbance coil current varies to keep linkage flux constant. Conventional analysis is usually formulated with constant current and does not provide correct evaluation of drift of magnetic field in the magnet. This paper proposes a method of numerical analysis of magnetic field considering conservation of linkage flux in a superconducting magnet under a persistent current mode operation. This method is applied to evaluate drift of the magnetic field in a superconducting magnet for magnetic resonance imaging due to external magnetic disturbance. Analysis results show good agreement with the experimental results. 相似文献
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An improved functional approach for designing MRI (magnetic resonance imaging) main magnets with active shielding is presented.
By nulling one or two external moments as well as a certain series of internal moments of the magnetic field, new designs
with improved shielding in combination with or without shorter magnet lengths are obtained. The improved method can be employed
to design short and practical superconducting magnets at any given field strength. The resulting designs yield the desired
field homogeneity inside the region of interest without using superconducting shim coils. This approach requires only a modest
amount of computing power. One of the design steps, a contour plot of the continuous current solutions, can be utilized to
study stretch goals for favorable design parameters. 相似文献