Low-speed aerodynamic characteristics and effects of the blockage ratio of an axisymmetric capsule configuration are experimentally investigated. The flow conditions in a closed-type test section with high blockage ratio are obtained by setting a circular duct coaxially in the open-type test section of the wind tunnel. The aerodynamic loads of similar scale model of three kinds with body diameter of 100, 180 and 240mm are measured in both open-type and closed-type test sections. Also the pressure distributions along the model surface and along the duct wall are measured. From the investigations of experimental results, the following major conclusions are obtained on aerodynamic characteristics of such capsule-type configurations: (1) It is expected that the drag force of capsule-type configuration is strongly affected by blockage ratio effects. (2) The usual method of the wind tunnel wall effect correction is applicable to prediction of lift and pitching moment coefficients, but not sufficient to drag coefficient. (3) The velocity profiles in the closed type test section are much different from those in the open-type test section. In case of the high blockage ratio, the flow which has been accelerated because of the decrease of the section area, is bent by the curvature of the model tail and separates at the trailing edge. Such phenomena make the flow field complicated and result in the increase of drag force.
