Abstract
Wind tunnel experiments concerned with the air flows behind the bluff-plates are described. The experiments with wind tunnel are to investigate the followings ; (1) The effects of the profiles of the approaching flows on the cavities of the two-dimensional bluff-plate model, (2) The effects of the aspect ratios of the bluff-plate models on the cavities of them. In the experiment (1), the wind velocity profiles of the approaching flows are changed in six degrees by the regular arrangements of two-dimensional roughness elements in up-stream region of the two-dimensional bluff-plate model. In the experiment (2), the aspect ratios of the bluff-plate models are varied from 16 to 2. Each bluff-plate is placed under the same boundary layer of the approaching flow. Mean and turbulent velocities are measured two-dimensionally by I-type hot-wire anemometer. Flow reattachment lengths, turbulent intensity profiles and the peak frequencies of power spectra are investigated in relation to H/δ, H/z_0 and W/H, in which H and W are the height and the width of bluff-plate model, δ and z_0 are boundary layer thickness and roughness parameter of approaching flow, respectively.
