On the generation of turbulence with a perforated plate

The root-mean-square of the turbulence velocity fluctuation components, u' and u', and the integral length scale, L, were measured downstream of a perforated plate inside a wind tunnel test section using a hot-wire anemometer. Nine combinations of three hote diameters (D = 25.4. 38.1 and 50.8 mm) and three plate solidity Values (sigma = 35%, 50%, and 60%) were investigated at three downstream locations (X = 20D, 30D and 40D) for three Reynolds number values (Re = 15,000, 22,000 and 29,000). Over the range of conditions considered. the results indicated that Re had no obvious effect on the normalized turbulence parameters u'/U, upsilon'/U and L/D. The dimensionless turbulence intensity decreased with X/D with a power law relationship, but increased with sigma in an exponential fashion over the range of values considered. The plate with a 35% solidity was found to possess the highest degree of homogeneity in terms of the uniformity of the turbulence intensity over any cross-section. The turbulence was more uniform in the region where the corresponding flatness factor, F, of the turbulence fluctuation velocity was approximately equal to 3. (C) 2003 Elsevier Inc. All rights reserved.