D212 回転円盤流中に導入された強い撹乱による境界層遷移

概要

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A laminar to turbulent transition process of a three-dimensional boundary layer in rotating-disk flow initiated by localized disturbances was experimentally investigated by a single hot-wire probe in the laboratory frame. To generate the localized disturbances, a pulsejet was issued into the rotating-disk flow from a small hole, where the boundary layer is slightly subcritical to the cross-flow instability. The hot-wire analyses showed that the point disturbance develops into a wave packet and its velocity fluctuation is spatially amplified. It was found that as a packet grows downstream, the breakdown to turbulence occurs leading to the formation of a turbulent patch. Further analyses also showed that the turbulent patch propagating in the wedge region is accompanied with the two families of traveling waves, which consist of the so-called cross-flow and streamline-curvature modes. The configuration in the plane view of the turbulence region is a crescent, which is different from an arrowhead shaped turbulent spot in a two-dimensional boundary layer. It was also found that the leading edge and trailing edge of the turbulent patch convect in the angular direction at celerity of 0.85 and 0.47 angular velocity of the disk-rotation, respectively.
日本流体力学会の論文
2000-07-25