共查询到19条相似文献,搜索用时 78 毫秒
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本文介绍了可控功率源电磁勘控的基本原理,它的研究任务及在地球物理应用方面的要求.讨论了国外脉冲磁流体发电机的特点,它的研究现状,未来前景及研究等问题. 相似文献
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盘式磁流体发电机工质因其主要吸收切线方向法拉第电流产生的自激焦耳热而形成非平衡电离等离子体。当盘式通道型线一定时,等离子体松弛区域的变化将改变发电通道入口等离子体吸收自激焦耳热区域的大小,引起发电通道入口等离子体电离状态变化,导致等离子体非平衡电离不稳定,严重影响发电机输出性能。本文采用非平衡盘式磁流体发电机的非稳态准一维数学模型进行数值模拟,分析较高磁感应强度下盘式磁流体发电机等离子体松弛区域对等离子体稳定性和磁流体流动特性的影响。分析结果表明:当发电通道型线和气体滞止状态一定时,等离子体松弛区域的改变抑制发电通道中电子数密度的波动,维持等离子非平衡电离的稳定性,促进发电机性能的提高;磁感应强度越高,等离子体松弛区域越小,最优阳极位置越靠近圆盘中心,发电通道中等离子体越容易达到非平衡电离的稳定;等离子体松弛区域的改变抑制了发电通道中或发电通道前等离子体流动中激波的产生,维持了发电通道中等离子体适当的超音速流动,促进发电机性能的提高;磁感应强度越大,发电通道中激波的产生越受等离子体松弛区域的影响,发电机的性能极易恶化。 相似文献
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在磁流体发电机中,为了提高工质电导率,通常需要加入少量低电离电位的碱金属,即种子。前期研究表明,在一定工况下存在最佳种子份数使发电机性能最优。本文通过非稳态准一维数值模拟,研究了盘式磁流体发电工质电离、等离子体流动和发电机性能特性,获得了热源参数和磁感应强度对最佳种子份数影响的变化规律,提出较宽最佳种子份数变化范围的调控方法。模拟结果表明,对于所给定的发电通道,在热源条件一定时,随着磁感应强度增加,最佳种子份数及其变化范围减小,种子流量的控制越精确。当磁感应强度一定时,随着热源滞止压力降低,最佳种子份数几乎保持不变,而且,最佳种子份数的变化范围增大,降低了种子流量控制的要求。另外,磁感应强度越低,在较低的热源滞止压力条件下,最佳种子份数变化范围越宽。 相似文献
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本文的目的是说明不同设计参数对发电机临界转速的影响,并阐明所谓"临界转速"的意义。根据作者的经验,"临界转速"有许多不同的意义或定义。因此,同一物体的临界转速值也不尽相同。为此作者提出了"临界转速"的定义。 相似文献
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为了实现对磁场测量仪器进行计量检定,设计并实现一种高准确度的磁场发生器标准装置。该装置采用磁屏蔽技术,设计了坡莫合金材料制作的多层屏蔽结构,形成了标准磁环境;设计由数模转换器(DAC)、互导放大器、CPU、输出控制电路、直流基准电源、消磁电流源、显示器和键盘等外围设备组成的数字式磁场控制器,磁场控制器控制通过加勒特线圈的电流以达到输出标准磁场的目的。该装置将模拟量转换成数字量,产生的标准磁场具有高分辨率和高准确度的特点。 相似文献
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Katsunori Yamada Tetsuhiko Maeda Yasuo Hasegawa Yoshihiro Okuno 《Electrical Engineering in Japan》2006,156(1):25-32
The performance of a liquid metal MHD generator is investigated with a two‐dimensional numerical simulation. The effects of the electrode length, the position of current lead connection, and the insertion of an insulator on the performance are examined taking account of the current flow in the electrode. There exists an optimal electrode length for a given distribution of applied magnetic flux density. For a short electrode, the efficiency decreases because the power output becomes small. For a long electrode, on the other hand, the efficiency also decreases owing to the leakage current from the upstream and downstream edges of the electrode. An optimal current lead position was revealed. This fact is ascribed to the distributions of induced magnetic field and the current flow in the electrode. It was found that insertion of the insulator is effective for improving the performance, by which the eddy current can be reduced. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 25–32, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/ eej.20165 相似文献
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Shin'ichi Wakui Kazumasa Ide Miyoshi Takahashi Gustavo Montoya Futoshi Hiyama Yasuomi Yagi 《Electrical Engineering in Japan》1998,123(3):73-83
This paper describes variations of turbine generator steady-state reactances for load conditions. When the turbine generator is of small size, magnetic saturation of the stator and rotor core is a problem. Therefore, it is important to understand the variations of the reactances for load conditions. The reactances of a 592-MVA turbine generator are calculated with d- and q-axis equations considering magnetic saturation and two-dimensional numerical magnetic field analysis. The results are as follows. (1) The equivalent synchronous reactances considering cross-magnetizing are smaller than the original synchronous reactances for load conditions. (2) Numerical values of the d- and q-axis mutual reactance and the field and q-axis mutual reactance are at their maximum when the d-axis linkage flux is nearly equal to the q-axis linkage flux under constant voltage. (3) The d-axis synchronous reactance drops with increasing reactive power under constant voltage and active power, but the q-axis synchronous reactance increases. (4) The variation of the equivalent d-axis synchronous reactance with increasing reactive power is similar to that of the d-axis synchronous reactance, but the variation of the equivalent q-axis synchronous reactance is different from that of the q-axis synchronous reactance. © 1998 Scripta Technica. Electr Eng Jpn, 123(3): 73–83, 1998 相似文献
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为了研究风速突然变化对永磁风力发电机主轴的电磁力作用,特别是在已发生一定的主轴偏心的情况下风速突变对主轴的影响,利用数学表达式和仿真对气隙磁场进行了计算和分析。根据发电机气隙偏心故障时气隙磁场变化的特点,计算气隙磁导和磁场密度,并利用ANSOFT MAXWELL软件建立永磁风力发电机的二维模型,分析电流变化引起的电磁力及其对主轴的作用。仿真结果表明:风速突变引起的电流变化影响永磁风力发电机气隙磁密。转子偏心使发电机转子产生沿偏心方向的磁拉力,风速突变时转子收到的不平衡磁拉力比正常风速运行更大。 相似文献