【摘要】 采用不同尺度、不同铺设密度的二维正方形粗糙元,在环境风洞中对大气表面层进行了模拟.使用粒子图像速度场仪对所模拟的大气表面层风速廓线、湍流强度进行了测量.结果表明:当粗糙元的铺设长度达到实验段入口高度的12倍以上时,依靠自然形成法所模拟的对数风速廓线高度可达实验段高度的60%;空气动力学粗糙度Z0最高可达粗糙元尺度的0.4~0.5倍,且Z0随粗糙元铺设区到测量断面的距离呈指数变化;同一高度上湍流强度随粗糙元铺设间距的增加而减小,当廓线高度达到实验段高度的40%以上时,湍流强度不随粗糙元大小及铺设密度的变化而变化,其大小为12%~13%.实际应用中,在已知所需Z0和摩阻风速U*的情况下,可通过粗糙元尺度及铺设密度的不同组合获得满足要求的大气表面层,并确定实验模型区的位置和实验段的入口风速.更多还原

【Abstract】 In the wind tunnel,the atmospheric surface layer was simulated by the naturally forming method with square-bar roughness elements having different height and different paving density.The atmospheric surface layer profiles and turbulence intensities were measured by particle image velocimetry.The results show that when the paving length is more than 12 times of the inlet height of the experimental section,and the profiles’ logarithmic height can be 60% of the experimental section height.The maximum value of the aerodynamics roughness,Z0,is about 40%-50% of the roughness element height,and Z0 changes exponentially with the distance from the last roughness element to model position.Moreover,at the same level,the turbulence intensities decrease with the increase of the paving distance.When the level reaches more than 40% of the experimental section height,the turbulence intensities are almost the same.Our results indicate that,in the practical application,the required atmospheric surface layer can be achieved by the different combination of roughness element height with paving density,and the experimental model position and the section inlet velocity can be determined if the needed Z0 and U* are known.更多还原