Many types of meteolorogical, environmental and boundary layer wind tunnels havebeen constructed to simulate atmospheric phenomena on buildings, structures andtransport of air pollutants. New types of 2-and 3-dimensional wind tunnels havebeen constructed in our laboratory, which have multiple-fans controlled by a computer. To simulate the required wind turbulence in the wind tunnel, each fan iscontrolled independently. First, the fan characteristics and its control methods toproduce the turbulence are discussed. Second, a few examples of longitudinal turbulent flow in the 2-D wind tunnel are presented.
Generating large-scale 3-D air turbulences similar to real situations in spatial characteristics defies the conventional wind tunnel test procedure but is requisite for evaluating the effect of turbulence of natural wind in engineering bridges and other large structures of optimum design matching the level of aerodynamic stability required. The authors added functional refinement to the 2-D blade rows and damper in the wind tunnel flow active system and also devised adjustable floor spires and blocks as another active flow control alternative. The prospect is good that selective use of these active flow control methods can successfully reproduce the large-scale 3-D air turbulences.
Ms.Kato, in her report in No.59 of this journal, has introduced two conditions for simulation of atmospheric turbulence in wind tunnels. This discussion points out that one of the condition is based on an assumption and that the conditions are not sufficient.
We have installed two wind tunnels of closed return type for carrying out our research in wind environment around tall buildings, aerodynamic stability of structures, and design of external materials. One of these tunnels has a working section of 1.8m in height, 2.0m in width and 16m in length. The other has a working section of 2.0m in height, 3.0m in width and 16m in length. The characteristics and performance of the wind tunnels are presented in this paper.