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

通过用各自独立的伺服电机控制垂直阵列中的6个小风扇，在高度为600 mm、风宽为200 mm的风洞工作段内产生了两次火灾相关的大尺度湍流气流。只有在这种类型的控制系统中才能模拟如此大尺度的湍流风。主要研究成果如下：(1)提出了一种通过测量功率谱与标记谱之比来修正输入电压时程，从而产生具有目标谱的湍流风的控制算法。在0.0~3.5 Hz的频率范围内，均方根误差达到23.6%。(2)提出了一种控制算法，通过控制输入电压时程的相位来产生具有目标谱和垂直方向目标相干性的湍流风。对阻塞率为10%的方形圆柱体进行了风压实验。功率谱特性在低频段呈现出一种特殊的趋势。(4)可以产生比风洞尺度更大的纵向湍流尺度。(5)这种多风机控制系统的风洞可以进一步发展为用三维谱模型模拟湍流风。

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.