AIAA JOURNAL, vol.44, no.5, pp.1065-1072, 2006 (SCI-Expanded)
The flow around a square cylinder with a plate attached to it has been investigated experimentally in the Reynolds number range between 7.5 X 10(3) and 5.5 x 10(4). The plate was located at the center of the front face of the square cylinder at the beginning. To determine the effects of the incidence angle of the square cylinder-plate body on the pressure distributions and vortex shedding, the square cylinder with the plate was rotated. The incidence angle was varied from theta to 180 deg, corresponding to the position of the plate in the front and back face of the cylinder, respectively. The width of the cylinder and the plate were chosen to be the same at 28 mm. Measurements of shedding frequency and pressures on the surface of the cylinder were obtained. The results indicate that the Strouhal number based on D, the side length of the square cylinder, has a strong peak at theta = 12 deg. After that, it decreases and remains nearly constant in the range from 50 to 105 deg.Two weaker peaks have also been observed at theta = 112 and 162 deg. The positions of flow attachments, separations, and reattachments on the square cylinder due to the attached plate and the inclination of the body have been clearly obtained from the pressure distributions on the square cylinder and from the flow visualization photographs. Also, drag and lift coefficients of the square cylinder are calculated from the pressure distributions. Drag coefficient of the square cylinder has minimum and maximum values at approximately theta = 20 and 80 deg, respectively, whereas the lift coefficient has a minimum and a maximum at approximately theta = 110 and 150 deg, depending on the plate position. The reducing effects of the plate on the drag and lift forces are discussed.