Aerodynamic behaviour of rectangular prisms with sharp edges at high Reynolds number

Abstract

This research is aimed at depicting Reynolds number effect on bluff-body shapes with sharp edges. Nine rectangular prisms were tested: three fineness ratios (width-to-depth) of 2:1, 3:1 and 4:1 and three edge configurations, namely square edges, small chamfer and large chamfer. Tests were done in a pressurised wind tunnel for a Reynolds number range from 0.15 x 10 6 to 4 x 106 based on the depth of the prism and for a Mach number range from 0.075 to 0.3. The prisms were tested at angles of attack from -2° up to 10° in increments of 2°. The results from this study represent, to the author's knowledge, aerodynamic data at the highest Reynolds number reached for 2D rectangular prisms, in turbulent flow and for incompressible flow regime. Measurements of steady and unsteady wind loads were made using an external sidewall force balance and surface pressures. In addition, a wake survey was performed using a hot-wire probe. The fineness ratio, the edge treatment, the angle of attack of the prism, and the wind turbulence are shown to affect the aerodynamic characteristics of the prisms. These effects appear to be influenced by Reynolds number suggesting that there is a limit to the non-sensitivity of bluff-body shapes with sharp edges to Reynolds number.