Flow Past Permeable Manipulator Ring Placed in a Turbulent Pipe Flow (2nd Report, Turbulent Flow Field)

The flow past the manipulator ring with permeability in a fully developed turbulent pipe flow was investigated by measuring the turbulent flow field. The manipulator ring with permeability has a rectangular cross section and a height 0.14 times the pipe radius. The experiments were performed under four conditions of the open area ratio β for Reynolds number of 6.2×104. The results indicate that the response of the turbulent flow field to the manipulator ring was delayed as compared with that of the mean velocity field, and that difference increased with β. The values of turbulence intensities and Reynolds shear stress profiles near the reattachment point increased in the region near the wall as β increased, while those peak values that were taken at the locus of the manipulator ring height decreased as β increased. Considering the change of η defined in this paper, the separated shear layer was systemically attenuated as β increased. The increase of β with the manipulator ring in this study was a small influence in the turbulence quantities profiles near the reattachment point as compared with the case of the external flow.