• Axisymmetric blunt-based body
• base pressure
• boundary layer
• near-wake
• Wind tunnel investigation

A wind tunnel investigation is carried out to study the influence of the characteristics of the boundary layer developing over the surface of an axisymmetric bluff body upon its base pressure and near-wake flow features. Tests were carried out at Re = Ul/ν = 5.50 x 105, at which the boundary layer over the lateral surface of the body becomes turbulent before reaching the base contour. A strip of emery cloth was wrapped around the body circumference in order to modify the thickness and characteristics of the boundary layer. The results show that the base suctions decrease with increasing boundary layer thickness, measured 0.1diameter from the base contour. This variation is found to be connected with a reduction of the curvature of the streamlines at separation, and with a corresponding increase of the length of the mean recirculation region that is present behind the body.