Strouhal numbers of inclined flat plates

Abstract The shedding frequencies and associated Strouhal numbers of vortices behind a flat plate with beveled sharp edges have been studied experimentally at angles of attack α = 0°–90° and Reynolds numbers in the range 3.5 × 10 3 – 3.2 × 10 4 . The Reynolds number has no discernible effects on the relation between the Strouhal number and the angle of attack in the range α = 10°–90° with fully separated flow. As the plate incidence is gradually reducing in this range, the modified Strouhal number based on the effective plate width normal to the freestream is found to remain at a nearly constant level until the bevel angle is taken into effect, which causes a shift of the separation point from the front edge to the rear edge, resulting in a jump of the modified Strouhal number to another higher level of approximately constant value. Accordingly, by the use of a correction factor to account for the effect of bevel angle, a universal Strouhal number of 0.160 ± 0.003 can be obtained for α = 10°–90°. It is observed that at low angles of attack α = 0°–5°, the influence of Reynolds number becomes significant due to the occurrence of flow reattachment and is rather complex for plates with different bevel angles. It is also observed that the effect of blockage on Strouhal number measurements can be corrected by employing a simple correction formula.