Control of Turbulence in a Multiple-Fan Wind Tunnel

Abstract

In an Atmospheric Boundary Layer, turbulent shear stress or Reynolds stress is one of the most important factors to express the turbulent characteristics. In this study, the Reynolds Stress was simulated in an actively controlled turbulent wind tunnel, in which the turbulence was controllable. The Reynolds Stresses were reproduced in an uniform shear flow with grids (1), in a turbulent shear flow with grids (2), and in a turbulent flow by controlling both fans and airfoils (3). As the results showed, the Reynolds stress could be simulated with any one of these methods, however the obtained other turbulent parameters, such as integral scale and power spectrum were different for individual method. Moreover the transitions of the mean velocity, turbulent intensity, integral scale and power spectrum along the mean flow direction in the case of controlling the fans and airfoils were also examined.