Active control of turbulence for an atmospheric boundary layer model in a wind tunnel

Many types of meteorological and boundary layer wind tunnels have been used for a long time to simulate the atmospheric effects on large structures an d the transport of air pollutants. In addition, a few actively controlled w ind tunnels have been proposed to obtain more realistic effects on structur es. New types of multiple-fan wind tunnels have been developed in our labor atory. To produce the required wind turbulence in the tunnels, fans and osc illating airfoils were controlled independently by a computer. Statistical parameters, such as mean wind velocity, turbulence intensity, turbulence sc ale and power spectral density profiles in a boundary layer, were satisfact orily reproduced in the tunnel. In addition to these parameters, a Reynolds stress profile was achieved and corresponding coherent motions were observ ed in the boundary-layer flow. (C) 1999 Elsevier Science Ltd. All rights re served.