マイクロバブルによるテイラー・クエット流れの遷移抑制(流体工学,流体機械)

概要

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We investigated the interaction between microbubbles and Taylor-vortices, which are generated in a fluid layer between coaxial-rotating double cylinders. O (10μm)-diameter hydrogen bubbles were generated by water electrolysis and dispersed into the fluid layer. The maximum void fraction, which is estimated by the input power for the water electrolysis, was smaller than 0.02%. From the time averaged velocity distribution, which is observed by Ultrasonic Velocity Profiling (UVP), these values are changed with different tendency at Re/Re_c=3.0 or 4.0, where Re_c is the critical Reynolds number for onset of the primary instability. As initially expected, the existence of the microbubbles does not modify the axial wavelength of the vortices and the frequency of the azimuthal waves either. However, the power of the modulation wave component, which comes from the flow instability, is lowered by the addition of microbubbles at Re/Re_c=8.0. This phenomenon is caused by the rising bubbles with the pattern, which makes inhomogeneous local void fraction.
2010-12-25