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Experimental Study of MHD-Assisted Mixing and Combustion Under Low Pressure Conditions
作者: 高岭   张百灵   李益文   樊昊   段成铎   王宇天   来源: 等离子体科学和技术(英文版) 年份: 2016 文献类型 : 期刊 关键词: assisted   Magneto   combustion   chamber   mixing   MHD   plasma   Dynamics(MHD)   Hydro  
描述: In order to reveal the mechanism of MHD-assisted mixing, and analyse the major parameters which influence the effect of MHD-assisted mixing, experiments of MHD-assisted mixing are carried out with a non-premixed butane-air combustion system. The evolvement of the discharge section and the effect of MHD-assisted mixing on combustion are investigated by changing the magnetic flux density and airflow velocity. The results show that the discharge area not only bends but also rotates around the centered wire electrode, which are mainly caused by the Lorentz force. Moreover, the highest curvature occurs near the centered wire electrode.The discharge localizes near the surface of the wire electrode and annular electrode when there is no ponderomotive force. However, if the ponderomotive force is applied, the discharge happens between these two electrodes and it gradually shrinks with time. The discharge area cannot localize near the annular electrode, which is due to the increase of energy loss in the airflow.When the airflow velocity exceeds a certain value, the discharge section becomes unstable because the injected energy cannot maintain the discharge. The rotation motion of the discharge section could enlarge the contact surface between butane and air, and is therefore beneficial for mixing and combustion. Magnetic flux density and airflow velocity are critical parameters for MHD-assisted mixing.
低气压直流辉光放电数值模拟与实验研究
作者: 张百灵   王宇天   李益文   樊昊   高岭   段成铎   来源: 高电压技术 年份: 2016 文献类型 : 期刊 关键词: 正常辉光   气体放电   异常辉光   电子数密度   等离子体   阴极位降  
描述: 为进一步探究低气压直流辉光放电机理,建立了基于局部平衡假设的2维直流辉光放电模型,研究了正常辉光向异常辉光放电的转变过程及其放电特性,并将异常辉光放电数值模拟结果与实验结果进行对比分析。结果表明,正常辉光放电时,在放电电压小幅增大的情况下,放电区域的扩大使放电电流增大,阴极位降区厚度减小,并出现明显的负辉光区。进一步增大放电电压,放电将覆盖整个阴极表面,可以明显区分出阴极位降区、负辉光区和正柱区,此时放电转变为异常辉光放电;放电电压为400 V时的阴极位降区电场强度高达3 200 V/cm。异常辉光放电、气压不变时,增大放电电压不会改变放电结构,但负辉光区的电子数密度增大使电流增大、放电增强;放电电压为400 V且气压在50~420 Pa之间时,放电电流将随气压的升高而增大。
分段法拉第磁流体发电通道流动特性数值模拟
作者: 张百灵   段成铎   李益文   高岭   王宇天   朱涛   来源: 推进技术 年份: 2016 文献类型 : 期刊 关键词: 冲压发动机   磁流体   流场特性   数值模拟   发电通道  
描述: 27.7%,马赫数降低25%,磁作用数升高至1时,出口速度将降至临界声速,马赫数降为1,出口温度较基准态升高20.8%;通道能量转化率越高,通道内壁逆压梯度越大,流动在内壁上容易发生分离;负载系数
基于均匀模型的低气压电容耦合射频放电特性研究
作者: 王宇天   张百灵   李益文   樊昊   高岭   庄重   来源: 真空科学与技术学报 年份: 2016 文献类型 : 期刊 关键词: 均匀模型   等离子体诊断   电子温度   电子数密度   电容耦合射频放电  
描述: 针对磁流体流动控制技术对大体积、均匀放电等离子体的需要,开展了低气压下平板型电容耦合放电特性实验研究,并基于均匀射频放电模型,联立能量平衡方程建立诊断模型对等离子体参数进行诊断。结果表明:气压较低时,放电为α模式,整个放电空间发光较为均匀,当气压大于500 Pa时,放电转变为γ模式,在电极附近出现负辉光区,但负辉光区较厚占据了整个放电空间,随着气压增大,负辉光区、法拉第暗区厚度减小,并在放电区域中心出现明显正柱区,正柱区面积随负载功率的增大而增大;放电为γ模式时,电流将随负载功率增大而增大,而电压先不变后增大,并且转折点负载功率随着气压增大而增大;电子数密度ne随负载功率的增大线性增大,而电子温度T_e只是略有增大,约为5500 K(0.47 e V)。
磁流体掺混促进燃烧初步实验研究
作者: 高岭   张百灵   李益文   阳鹏宇   樊昊   段成铎   权宇   王健   来源: 推进技术 年份: 2016 文献类型 : 期刊 关键词: 磁流体   掺混助烧   减排   等离子体  
描述: 为了有效控制污染物排放,降低航空对环境污染的影响,提出了一种磁流体掺混助燃技术。研制了磁流体掺混助燃实验系统,介绍了实验系统的基本组成,设计思想及运行情况。实验表明,利用等离子体能迅速点燃稀薄空气中的燃气;当线电极接通正极时,燃烧发生在以线电极为中心的扇形区域,当线电极接通负极时,燃烧只发生在线电极周围有限区域;在流场以及电磁场的综合作用下,可以使空气和燃气混合得更加均匀,增加空气和燃料的接触面积,使燃烧更充分,说明磁流体掺混技术起到了一定的减排效果。
Experimental Study of MHD-Assisted Mixing and Combustion Under Low Pressure Conditions
作者: 高岭   张百灵   李益文   樊昊   段成铎   王宇天   来源: 等离子体科学与技术(英文版) 年份: 2016 文献类型 : 期刊 关键词: 混合效果   磁流体   实验   磁通密度   燃烧系统   气流速度   压条   MHD效应  
描述: In order to reveal the mechanism of MHD-assisted mixing, and analyse the major parameters which influence the effect of MHD-assisted mixing, experiments of MHD-assisted mixing are carried out with a non-premixed butane-air combustion system. The evolvement of the discharge section and the effect of MHD-assisted mixing on combustion are investigated by changing the magnetic flux density and airflow velocity. The results show that the discharge area not only bends but also rotates around the centered wire electrode, which are mainly caused by the Lorentz force. Moreover, the highest curvature occurs near the centered wire electrode.The discharge localizes near the surface of the wire electrode and annular electrode when there is no ponderomotive force. However, if the ponderomotive force is applied, the discharge happens between these two electrodes and it gradually shrinks with time. The discharge area cannot localize near the annular electrode, which is due to the increase of energy loss in the airflow.When the airflow velocity exceeds a certain value, the discharge section becomes unstable because the injected energy cannot maintain the discharge. The rotation motion of the discharge section could enlarge the contact surface between butane and air, and is therefore beneficial for mixing and combustion. Magnetic flux density and airflow velocity are critical parameters for MHD-assisted mixing.
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