Pilot study on turbulence wind tunnel with numerically controlled multiple fans.

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By controlling six small fans in an vertical array with respective individual servo-motors, turbulent air streams with a large scale correlated in two firections were created in a wind tunnel working section with the height of 600 mm and the wind width of 200 mm. Such a large scale turbulence wind can only be simulated in this type of control system. Major achievements are concluded as follows ;(1)A control algorithm was developed to create a turbulent wind with a target spectrum, by modifying the input electric voltage time history in terms of the ratios of measured power spectrum to taget one. Root mean square error of 23.6% in the frequency range between 0.0 and 3.5 Hz was achieved.(2)A control algorithm was developed to create a turbulent wind with a target spectrum and a target co-coherence in the vertical direction, by applying the method mentioned in (1) for the spectrum and by controlling the phase of input electric voltage time history. Root mean square error of 15% was achieved.(3)Wind pressure experiments were conducted for a square cylinder with the blockage ratio of 10%. The power spectral characteristics showed a special tendency in a low frequency range.(4)A larger longitudinal turbulence scale than the scale of the wind tunnel can be created.(5)This wind tunnel with multiple fan control system can be developed further for the simulation of turbulent wind with a three dimensional spectral model.