Studies on Griffin universal Strouhal number for bluff bodies with different cross-sectional shapes under simulated atmospheric flow conditions

摘要

Strouhal number is an important aerodynamic parameter in describing the vortex shedding frequency in the wake region. Pressure measurement studies have been conducted on models of three structures with different plan shapes - circular, octagonal and irregular shape with a central recess, under simulated atmospheric open terrain conditions. Based on the experimental data it is found that for circular and octagonal structures with regular plan shapes, the values of Griffin universal Strouhal number, G obtained are 0.067 and 0.074 respectively whereas, for the irregular plan shape model tested, the value of G = 0.065 is satisfied, only for limited angles of wind incidence. (θ = 0°, 90°, 150°, 180°, and 270°). Non-compliance of the above universal value of G for other angles of incidence is believed to be due to significant change in the value of mean drag coefficient as exhibited by the test data.