| Research Abstract |
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
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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
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