格栅湍流场风参数沿风洞轴向变化规律

摘要

Grid-generated wind fields are commonly applied in various wind tunnel tests to ob-tain aerodynamic parameters of flexible bridges.In this work,wind characteristics of grid-gener-ated wind field were investigated at different distances from the grid section along the wind tun-nel.The wind characteristics principally depend on the distance,the thickness of slat and the length of the unit grid side.The results indicate that the mean wind velocity descends steeply and soon afterwards steadies with the distance.The total turbulent energy declines and the dominant energy migrates to the higher frequency region with the distance:the turbulence intensity de-clines and the integral length scale increases;non-dimensional power-spectral density forms and non-dimensional frequencies corresponding to the peak value remain unchanged,but the peak val-ues decline.Two specific turbulent conditions were adjusted according to these contributing fac-tors:similar turbulence intensities with different integral length scales;similar integral length scales with different turbulence intensities,founding the basis to investigate the effects of main wind characteristics on the aeroelastic parameters.%格栅湍流场常用于各类风洞试验中，桥梁断面气动参数均与来流风参数有关。对不同格栅湍流场下的风参数沿风洞轴向变化的规律进行了研究，得出风参数主要与测点与格栅断面间距、格栅板条厚度和单元格栅边长有关。随着间距增加，平均风速短期内急剧衰减，然后趋于稳定。随着间距增加，来流湍流的总能量减小而主要能量迁移至高频区域：湍流度呈指数衰减，湍流积分尺度呈增长趋势；约化风谱形状保持相似，峰值对应约化频率值基本保持不变，但峰值变小。另外根据风参数的变化规律，调试出2类特定的湍流场参数：湍流度相似而湍流积分尺度不同的湍流场和湍流积分尺度相似而湍流度不同的湍流场，以便于详尽研究主要风参数对桥梁断面气动参数的影响。