共查询到20条相似文献,搜索用时 687 毫秒
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采用漩涡破碎(EBU)燃烧模型、k-ε双方程湍流模型及SIMPLEC算法,对等离子发生器内部的燃烧流场进行了数值模拟,得到了关于等离子燃烧流场相关特性参数分布。该数值模拟对等离子发生器的研究具有指导作用。 相似文献
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论述了用于金属材料表面热处理的等离子弧发生器的工作原理、结构特点和参数设计.试验证明这种发生器对材料的表面局部硬化非常有效. 相似文献
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等离子体流动控制技术已经在流动控制领域成为热点和焦点。为了研究等离子体对于飞翼布局飞机稳定性的影响,本文研究中采用闭环飞行控制律对飞翼布局飞机模型的操纵舵面进行操控,同时增加等离子控制,对该模型飞机在失速迎角附近区域开展三自由度(3DoF)的虚拟飞行试验研究。结果表明,等离子打开后,在俯仰运动上,使得飞机俯仰振荡幅值变小,增快振荡衰减,在滚转运动上,对滚转角命令的跟随性变好;在偏航运动上,增加了偏航阻尼,改善了原来偏航运动的偏离问题。因此,等离子流动控制对于飞翼布局飞机在失速迎角附近的稳定性改善具有良好的效果,对未来等离子技术的实际应用提供了借鉴和指导。 相似文献
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大后掠三角翼和双三角翼因为在高速流场中有较低的波阻,一直是高速运输机的候选布局,这种机翼的最大缺点是升力线斜率相对较小,限制了飞机的低速性能,特别是它的起飞着陆性能,加上其翼梢流场很容易在较低升力系数时就处于失速状态,会给飞机带来不利的上仰不稳定性,同时大大减弱了副翼的效率。为了改进这种机翼的固有缺陷,空气动力学专家们曾设计了诸如前缘襟(缝)翼、翼刀、涡流发生器等来减缓特别是翼梢区的流场分离,但这类机械系统或气动设计都会带来一些机械设计和重 相似文献
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应用流体控制方程、传热传质方程、粒子输运方程、Maxwell电磁场方程建立多场耦合数学模型,通过数值计算方法研究超声速等离子喷枪内外等离子体流动特性。所采用的内送粉三维模型包含阴、阳电极固体以及阳极边界层区域,考虑了等离子气体的电离与复合反应,以及局域热平衡效应,得到了超声速等离子喷涂在纯氩和氩氢混合气氛中的气流温度场、速度场分布以及电弧电压分布。结果表明:在加入氢之后,喷枪内等离子体温度提高了30%,速度提高了67%;喷枪外气流速度和温度在距喷嘴出口0~50mm间梯度变化大于喷涂距离50~100mm,且径向速度和温度梯度变化随着喷涂距离增大越来越小。计算得到的电弧电压与测量值相差4.4%,说明了考虑阳极边界层后计算模型的合理性。 相似文献
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受吴仲华先生"叶轮机械三元流动理论"的启发,在前期压气机等离子体流动控制研究的基础上,进一步提出等离子体激励式压气机的概念,即将等离子体激励融入到S1,S2流面压气机气动设计之中,以释放常规压气机设计中失速裕度、负荷极限等因素的约束。本文旨在探讨等离子体流动控制在新一代高负荷压气机中应用的前景和研究趋势,通过原理论证与实例分析,首先阐述了等离子体激励式压气机的概念,然后梳理了压气机等离子体流动控制研究的若干进展,以论述等离子体激励式压气机设计的研究基础,最后给出了等离子体激励式压气机的典型技术路径和理论基础。 相似文献
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The Near-Earth Plasma Environment 总被引:1,自引:0,他引:1
Robert F. Pfaff Jr. 《Space Science Reviews》2012,168(1-4):23-112
An overview of the plasma environment near the earth is provided. We describe how the near-earth plasma is formed, including photo-ionization from solar photons and impact ionization at high latitudes from energetic particles. We review the fundamental characteristics of the earth’s plasma environment, with emphasis on the ionosphere and its interactions with the extended neutral atmosphere. Important processes that control ionospheric physics at low, middle, and high latitudes are discussed. The general dynamics and morphology of the ionized gas at mid- and low-latitudes are described including electrodynamic contributions from wind-driven dynamos, tides, and planetary-scale waves. The unique properties of the near-earth plasma and its associated currents at high latitudes are shown to depend on precipitating auroral charged particles and strong electric fields which map earthward from the magnetosphere. The upper atmosphere is shown to have profound effects on the transfer of energy and momentum between the high-latitude plasma and the neutral constituents. The article concludes with a discussion of how the near-earth plasma responds to magnetic storms associated with solar disturbances. 相似文献
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R. J. Strangeway 《Space Science Reviews》1991,55(1-4):275-316
Many significant wave phenomena have been discovered at Venus with the plasma wave instrument flow on the Pioneer Venus Orbiter. It has been shown that whistler-mode waves in the magnetosheath of the planet may be an important source of energy for the topside ionosphere. Plasma waves are also associated with thickening of the ionopause current layer. Current-generated waves in plasma clouds may provide anomalous resistance resulting in electron acceleration, possibly producing aurora. Ion-acoustic waves are observed in the bow shock, and appear to be a feature of the magnetotail boundary. Lastly plasma waves have been cited as evidence for lightning on Venus. 相似文献
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Cassini Plasma Spectrometer Investigation 总被引:1,自引:0,他引:1
《Space Science Reviews》2004,114(1-4):1-112
The Cassini Plasma Spectrometer (CAPS) will make comprehensive three-dimensional mass-resolved measurements of the full variety of plasma phenomena found in Saturn’s magnetosphere. Our fundamental scientific goals are to understand the nature of saturnian plasmas primarily their sources of ionization, and the means by which they are accelerated, transported, and lost. In so doing the CAPS investigation will contribute to understanding Saturn’s magnetosphere and its complex interactions with Titan, the icy satellites and rings, Saturn’s ionosphere and aurora, and the solar wind. Our design approach meets these goals by emphasizing two complementary types of measurements: high-time resolution velocity distributions of electrons and all major ion species; and lower-time resolution, high-mass resolution spectra of all ion species. The CAPS instrument is made up of three sensors: the Electron Spectrometer (ELS), the Ion Beam Spectrometer (IBS), and the Ion Mass Spectrometer (IMS). The ELS measures the velocity distribution of electrons from 0.6 eV to 28,250 keV, a range that permits coverage of thermal electrons found at Titan and near the ring plane as well as more energetic trapped electrons and auroral particles. The IBS measures ion velocity distributions with very high angular and energy resolution from 1 eV to 49,800 keV. It is specially designed to measure sharply defined ion beams expected in the solar wind at 9.5 AU, highly directional rammed ion fluxes encountered in Titan’s ionosphere, and anticipated field-aligned auroral fluxes. The IMS is designed to measure the composition of hot, diffuse magnetospheric plasmas and low-concentration ion species 1 eV to 50,280 eV with an atomic resolution M/ΔM ∼70 and, for certain molecules, (such asN
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+ and CO+), effective resolution as high as ∼2500. The three sensors are mounted on a motor-driven actuator that rotates the entire instrument over approximately one-half of the sky every 3 min.This revised version was published online in July 2005 with a corrected cover date. 相似文献
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温度、密度对目标等离子体隐身效果影响的FDTD分析 总被引:1,自引:0,他引:1
采用等温近似,给出覆盖目标的不均匀的、各项同性的、热的、碰撞的、等离子体的电磁反射的三维FDTD算法的公式。在一维条件下,计算了不同密度分布、不同温度的等离子体对电磁波的反射系数。给出了温度、密度对电磁波在等离子体中的碰撞吸收的影响。结果显示,增大等离子体的温度和密度将有利于等离子体对电磁波的吸收,增大吸收的带宽,减小等离子体覆盖目标对电磁波的反射。 相似文献
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D. A. Gurnett W. S. Kurth R. R. Shaw A. Roux R. Gendrin C. F. Kennel F. L. Scarf S. D. Shawhan 《Space Science Reviews》1992,60(1-4):341-355
The purpose of the Galileo plasma wave investigation is to study plasma waves and radio emissions in the magnetosphere of Jupiter. The plasma wave instrument uses an electric dipole antenna to detect electric fields, and two search coil magnetic antennas to detect magnetic fields. The frequency range covered is 5 Hz to 5.6 MHz for electric fields and 5 Hz to 160 kHz for magnetic fields. Low time-resolution survey spectrums are provided by three on-board spectrum analyzers. In the normal mode of operation the frequency resolution is about 10%, and the time resolution for a complete set of electric and magnetic field measurements is 37.33 s. High time-resolution spectrums are provided by a wideband receiver. The wideband receiver provides waveform measurements over bandwidths of 1, 10, and 80 kHz. These measurements can be either transmitted to the ground in real time, or stored on the spacecraft tape recorder. On the ground the waveforms are Fourier transformed and displayed as frequency-time spectrogams. Compared to previous measurements at Jupiter this instrument has several new capabilities. These new capabilities include (1) both electric and magnetic field measurements to distinguish electrostatic and electromagnetic waves, (2) direction finding measurements to determine source locations, and (3) increased bandwidth for the wideband measurements.Deceased 相似文献
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A two dimensional model of the transition region and the lower corona, based on the idea that the magnetic flux is strongly
concentrated at the boundaries of the supergranular convection cells, has been proposed by Gabriel in 1976. The plasma moves
along the open magnetic field lines, which define the the so-called "funnel," and eventually builds up the solar wind.
Based on a two dimensional funnel model we investigate the stationary plasma flow at its central line, taking heat conduction,
radiative losses, and a heating function into account. The derived height profiles of the plasma properties within the funnel
are presented.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献