Structure and Stabilization of Thermal, Fluid-and Electrical Fields in High Speed Ionized Gases

研制了用于高速二维MHD湍流边界层温度测量的交叉激光相关测速仪和改进型偏振线反转系统，并进行了初步试验。利用VxB探头、光电二极管、压力传感器、发电机分段电极和电势探头等方法，采集了亚音速磁流体等离子体在有磁场和无磁场两种情况下的速度、温度、气体发射、压力和电信号。对速度数据的分析表明，即使在短时间的激波等离子体中，也可以建立统计稳定状态。通过比较频率空间和波数空间的速度功率谱，证明了泰勒扰动对流输送假说的正确性。已经清楚地证明，…激波等离子体同时具有两种不同的湍流结构，即在低波数范围内具有kolmogorov谱的三维各向同性湍流，以及在连续较高波数范围内具有k^&lt；-3&gt；依赖关系的二维各向同性湍流。结果表明，两种湍流结构均处于所谓的惯性子区，磁场对二维湍流结构的建立起着中心作用。在通道入口处给定扰动的情况下，求解了含时一维非线性MHD方程。有两种不同的传播速度，即对流速度和对流加音速。最后，我们用k-epsilon湍流模型进行了三维MHD通道流动分析，结果表明，在双分量二维构型的磁场作用下，一些严重的流体动力学不稳定性可以得到很好的抑制。较少

Construction and preliminary testings have been made on a crossed laser beam correlation velocimeter and a modified light polarization line reversal system for high speed two-dimensional MHD turbulent boundary-layer temperature measurement. Using these and othermethods involving VxB probe, photodiodes, pressure transducers, generator segmented electrodes and the potential probes, the velocity, the temperature, the gas emission, the pressure, and the electrical signals from subsonic magnetohydrodynamic plasma have been collected in both a combustion and a shock tube systems under conditions each with and without the magnetic field.Analyses of the velocity data have shown that even in a short duration shock plasma a statistically steady state could be established. The Taylor's hypothesis for convective transport of disturbances has evidently confirmed by comparison of the velocity power spectra in the frequency space and that in the wave number space. It has been clearly demonstrated tha … More t the shock plasma has two different turbulent structures simulteneously, namaly a Kolmogorov's 3-D isotropic turbulence with the k^<-5/3> spectrum in a low wave number range and also the 2-D isotropic turbulence with the k^<-3> dependence in the successive higher wave number range. We could show that both turbulent structures were in a so-called inertial subrange, and the magnetic field played a central role for establishing the 2-D turbulent structure.Further, the time dependent 1-D nonlinear MHD equations were solved with disturbances given at the channel entrance. There have been shown two distinct propagation speeds, i.e., the convective and the convective plus sonic speeds. However, it was also made clear that which disturbances could dominate, was decided by the upstream fluctuation processes.Finally, we performed a three dimensional MHD channel flow analysis with a k-epsilon turbulence model and showed that some serious fluiddynamical instabilities could be well suppressed under the magnetic field with a two-component 2-D configuration. Less