角柱を挿入した乱流境界層の流動と伝熱特性 : スプリッタプレートによる渦放出の制御  [in Japanese] Flow and Heat Transfer Characteristics of a Turbulent Boundary Layer with an Insertion of a Square Rod : Control of Vortex Shedding by a Splitter Plate  [in Japanese]

An experimental study was performed on a flat plate turbulent boundary layer disturbed by a square rod attached with a splitter plate. Spectrum analysis of the fluctuating velocity revealed that the periodical shedding of the Karman-like vortex from the square rod could be controlled by attaching the splitter plate to the square rod and suppressed with an increase of the plate length, L. It was found that noticeable heat transfer enhancement was achieved with the insertion of the square rod, but this enhancement became less noticeable with an increase of L. Skin friction acting on the flat plate was reduced but its magnitude was not significantly altered by changing the value of L. Therefore, the strength of the generated dissimilarity first increased and then decreased with an increase of L. Selective intensification of the interactive fluid motions near the wall was again concluded to be the generation mechanism of the dissimilarity. Furthermore, wavelet analysis applied to the fluctuating velocity signals indicated that this intensification of the interactive fluid motions was related to the near-wall fluid motion occurring in a synchronized fashion with the Karman-like vortex intermittently.