Evaluation of the Characteristic Features of a Large-Scale Turbulence Field : 1st Report, Performance of the Turbulence Generator

Abstract

A new scheme for an artificial turbulence generator was developed to realize a strong turbulence field with large scale turbulent eddies in a small wind tunnel. t is a sort of mechanical grid with small agitating wings randomly oscillated by pulse motors. The resultant turbulence had turbulence intensities of more than 10 % in the region far down-stream of the generator. It showed almost completely flat distributions of the mean velocity and the turbulent intensities across the test section. The power spectra had smooth and wide spread distributions. The inertial sub-ranges were observed for more than two orders of magnitude in wave-number. Its width exceeded the values obtained for the turbulent fields with far larger Reynolds numbers of more than 10⁶.