磁場保持される磁性流体液柱の横振動特性〔流体工学, 流体機械〕

概要

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We have investigated the stability and vibrational response of magnetic liquid columns held by Helmholtz coils. Theoretical resonance frequencies were derived from the linear potential theory prior to the experiment. During the experiment, a small quantity of a kerosene-based magnetic liquid was injected onto a lower pole plate. When the magnetic field was increased. a cylindrical column (height=9.78mm) was vertically formed between the two pole faces of the iron core Helmholtz coils. When the magnetic field was decreased, the column diameter exhibited hysteresis such that the column broke at a smaller diameter than that at formation. The coils holding the liquid column were then excited horizontally and the lowest mode (m=1,n=1) derived theoretically appeared in the measurements. The surface frequency response was measured optically using a CCD camera, a strobovision analyzer and a stroboscope for various magnetic field intensities and aspect ratios (mean diameter/height). We found that the resonance frequency of the mode (m=1,n=1) decreased with increse of the aspect ratio. The experimental resonance frequencies were in qualitative agreement with the theoretical predictions.
一般社団法人日本機械学会の論文
1997-08-25