Effects of corner cuts and angles of attack on the Strouhal number of rectangular cylinders

Abstract

Abstract.An investigation into the effect of corner cuts on the Strouhal number of rectangularcylinders with various dimensional ratios and various angles of attack is described. The Strouhal numbergiven as a function of corner cut size is obtained directly from the aerodynamic behavior of the body in auniform flow through a series of wind-induced vibration tests. For a quick verification of the validity ofthe Strouhal numbers obtained in this way, they are compared with the approximated the Strouhalnumbers based on Shiraishi’s early research. The test results show that the Strouhal number of the modelwith various corner cuts has a fluctuating trend as the angle of attack changes. For each cutting ratio asthe angle of attack increases at each cutting ratio above 15 o , the Strouhal number decreases gradually, andthese trends are more evident for larger corner cut sizes. However, a certain corner cut size which iseffective in reducing the wind-induced vibration can be identified by larger Strouhal numbers than thoseof other corner cut sizes. Three distinct characteristics of Strouhal number variation can be identified inthree regions which are termed as Region I, II, and III based on the general trend of the test results. It isalso found that the corner cut is effective in one region (Region-II) and less effective in another one(Region-III) when only the vortex-induced vibration occurs.Key words:Strouhal number; corner cut; angle of attack; wind tunnel experiment; rectangular cylinder